RESEARCH REPORT SERIES NO. 3
RESEARCH REPORT 
1985
ORNAMENTALS
ALABAMA AGRICULTURAL EXPERIMENT STATION 
AUBURN UNIVERSITY
GALE A. BUCHANAN, DIRECTOR AUBURN 
UNIVERSITY, ALABAMA
MAY 1985

FOREWORD
Two years ago the Alabama Agricultural Experiment
Station began a new publication series, the Research
Report Series, with Volume No. 1 summarizing current
research dealing with all phases of ornamental horticul-
ture research by Auburn University. Response from
members of the nursery industry indicated that such a
summary of available research information would be of
value to those involved in producing ornamentals com-
mercially. Furthermore, those responding said they
would like to see periodic updates. This publication is
our response to that stated interest.
We are pleased to offer this current report, and trust
that the information reported will be useful and con-
tribute to the success of individual nursery operations
and to the overall ornamentals industry in Alabama.
The team that prepared this publication included fac-
ulty and staff of three departments and two outlying
units of the Alabama Agricultural Experiment-Station
(AAES), state staff of the Alabama Cooperative Exten-
sion Service (ACES), and former graduate students in
horticulture. The contributors are:
Roger D. Anderson, Former Graduate Student in Hor-
ticulture
Hoyt E. Burgess, Associate Superintendent, Piedmont
Substation, AAES, 
Camp Hill
Gary S. Cobb, Superintendent, Ornamental Horticul-
ture Substation, AAES, Mobile
Douglas A. Cox, Assistant Professor of Horticulture,
AAES
D. Joseph Eakes, Former Graduate Student in Horti-
culture
Clyde E. Evans, Professor of Agronomy and Soils,
AAES
Donna C. Fare, Research Associate of Horticulture,
AAES
Charles H. Gilliam, Associate Professor of Horticul-
ture, AAES
Wallace A. Griffey, Superintendent, Piedmont Substa-
tion, AAES, Camp Hill
Austin K. Hagan, Plant Pathologist and Nematologist,
ACES
Gary J. Keever, Assistant Professor of Horticulture,
AAES
Leland W Lee, Former Graduate Student in Horticul-
ture
Willis C. Martin, Jr., Research Associate of Horticul-
ture, AAES
Lorie E. Merrill, Former Graduate Student in Horti-
culture
Dean R. Mills, Horticulture Research Specialist, Or-
namental Horticulture Substation, AAES, Mobile
Jacqueline M. Mullen, Extension Program Associate-
Plant Pathologist, ACES
Harry G. Ponder, Associate Professor of Horticulture,
AAES
Kenneth C. Sanderson, Professor of Horticulture,
AAES
Ronald L. Shumack, Head, Extension Horticulture,
ACES
James C. Stephenson, Assistant Superintendent, Orna-
mental Horticulture Substation, AAES, Mobile
Linda G. Waterhouse, Former Graduate Student in
Horticulture
John C. Williams, Professor of Research Data Analysis,
AAES
Gale A. Buchanan
Dean and Director
Alabama Agricultural
Experiment Station
Auburn University
CONTENTS
FOREW ORD ................................................... ............ 3
GREENHOUSE CROPS .................... .............. .... .............. 5
Fertilizer-Use Efficiency of Several Nitrogen Fertilizers
Applied to Potted Geranium ........ . ....................... 5
Comparison of Various Controlled-Release Fertilizers
on the Growth of Ficus benjamina ....... ......................... 6
Evaluation of Group IV Snapdragon Cultivars in Central Alabama .......... 6
Chemical Reduction of Induced Petal Abscission in Geraniums ............. 7
Effect of Fungicides on Rooting of Poinsettia Cuttings ................... 8
Tolerance of Four Potted Chrysanthemum Cultivars to Dursban ............ 9
W OODY ORNAMENTALS ..................................................... 10
Response of Woody Plants to Timing of Supplemental
Nitrogen Applications .............. .. ..................... 10
Comparison of Fertilizer Application Methods
for a Single Component Growth Medium ............. ............ 10
Response of Four Woody Ornamentals to Superphosphate
Incorporation and Osmocote Placement .......................... 11
Effect of Trickle Irrigation, Nitrogen Rate, and Method of
Nitrogen Application on Field-Grown Japanese Holly .................. 12
Container Growth Medium Temperature as Influenced by
Moisture Content .................... ...................... 13
Irrigation Scheduling Effects on Container Temperatures
and Plant Growth ..................... ..................... 14
Effects of Pruning on Root and Shoot Growth of Ornamentals ............. 18
Effects of Container Dimension and Volume on Growth of
Three Woody Ornamentals .......... ...................... 19
Woody Plants for Interior Environments.......................... 21
Promising Trees for the Southeast .......... .................... 22
DISEASE AND INSECT CONTROL ............................................ 25
Control of Entomosporium Leaf Spot on Photinia
Under Conditions of High Disease Pressure ........................ 25
Control of Anthracnose on Euonymus ............ ................... 26
Fungicides for Black Spot Control on Roses .......................... 27
Susceptibility of Ilex Cultivars to Black Root Rot .......................... 28
Control of Pseudomonas Leaf Spot on Magnolia grandiflora .............. 29
Pesticide Phytotoxicity and Residue Accumulation on Poinsettia ........... 30
Chemical Control of Fungus Gnats ............. ................... 31
COVER PHOTO. Members of the nursery industry view Alabama Agricultural Exper-
iment Station research during a field day at the Ornamental Horticulture Substation,
Mobile.
FIRST PRINTING 5M, MAY 1985
Information contained in this report is available to all persons
without regard to race, color, sex, or national origin.
GREENHOUSE CROPS
Fertilizer-Use Efficiency of Several
Nitrogen Fertilizers
Applied to Potted Geranium
Douglas A. Cox
Nitrogen applied to potted plants is absorbed by the plant,
retained by the growing medium, or lost by leaching or as a
gas. Quantity of N absorbed by the plant and retained by the
growing medium is a measure of fertilizer-use efficiency.
Poor efficiency results in waste of fertilizer material. In this
study the efficiency of several types of N fertilizer was deter-
mined using potted seed geranium, Pelargonium x hortorum
Jackpot.
Fourteen-day-old seedlings were potted in 4-inch standard
plastic pots of sphagnum peat moss, pine bark screened to
pass a 0.25-inch mesh, and perlite (1:1:2 by volume),
amended with 8 pounds single superphosphate, 5 pounds do-
lomitic limestone, 4 pounds Esmigran, and 2 tablespoons Se-
questrene 330 iron chelate per cubic yard. Plants were grown
90 days and received 43, 100-milliliter applications of 200
p.p.m. N solution of ammonium sulfate, ammonium nitrate,
calcium nitrate, or urea; 200 p.p.m. K was supplied in each
treatment by potassium sulfate. In another treatment, Os-
mocote 14-14-14 supplied N, P, and K in split application, 3.6
grams per pot incorporated at planting and 2.5 grams per pot
topdressed 53 days later. With Osmocote, no superphosphate
was incorporated and plants received 43, 100-milliliter appli-
cations of water only. The total amount of fertilizer N applied
in all treatments equalled 860 milligrams per pot. Analysis of
the medium prior to planting showed that pots filled to plant-
ing depth contained an average of 264 milligrams of N.
Therefore, 1,124 milligrams of N (fertilizer N + medium N)
were potentially available to each plant during the experi-
ment.
Leachate samples were analyzed for N at 10-day intervals
during the experiment to determine N loss by leaching. At
termination, shoot and root dry weights were determined and
N analyses were made on plant (shoot and root) and medium
samples. Data in table 1 are the percentages of N from fertil-
izer treatments and medium found in leachate, plant, and
medium and N which could not be accounted for by analysis.
Unaccounted-for N is assumed to be N lost from the medium
as ammonia or other nitrogenous gases.
Ammonium nitrate and calcium nitrate fertilizer treat-
ments resulted in the greatest shoot growth and ammonium
sulfate the least, with urea and Osmocote intermediate, table
1. Root growth was reduced by ammonium sulfate compared
with the other treatments; differences among the remaining
treatments were small. All treatments except ammonium sul-
fate produced commercially acceptable plants; ammonium
sulfate plants flowered 7-10 days later and youngest leaves de-
veloped chlorosis. Greatest plant absorption of N occurred
with ammonium nitrate, followed by urea and Osmocote,
and then by calcium nitrate and ammonium sulfate. Nitrogen
lost by leaching was greatest with ammonium sulfate, due to
low demand for N and water caused by poor growth, and cal-
cium nitrate, due to the ready leachability of nitrate N. Sig-
nificantly less N was lost by leaching with ammonium nitrate,
urea, and Osmocote. Percentage of N retained in the me-
dium was highest with Osmocote, indicating that some N re-
mained in the fertilizer granules at the end of the experiment.
Quantity of unaccounted-for N was greatest with urea and
ammonium sulfate; both fertilizers are subject to loss by con-
version to ammonia gas. Nearly all N supplied by ammonium
nitrate, calcium nitrate, and Osmocote could be accounted
for, indicating little N was lost as a gas with these fertilizers.
In summary, N-use efficiency was greatest with ammo-
nium nitrate and Osmocote, with 65 and 64 percent, respec-
tively, of N supplied being absorbed by the plant and retained
by the medium. Appreciable amounts of N were lost by
leaching in all treatments. With urea, N loss by leaching was
significantly less than the other treatments, but this was off-
set by greater loss of gaseous N. In practical terms, about 5
to 9 ounces out of every pound of N potentially available were
lost by leaching. Leaching must occur to prevent accumula-
tion of harmful soluble salts. Results show that N loss by
leaching can be reduced by choice of N fertilizer. Other ways
of reducing leaching loss include (1) when using water soluble
N fertilizers and irrigation, relating N rate to stage of growth
and avoiding excessive irrigation early in the crop and (2) with
slow-release fertilizers, splitting applications rather than
making a single application at planting. Practical methods of
controlling gaseous N loss have not been developed.
TABLE 1. GROWTH AND NITROGEN-USE EFFICIENCY OF 4-INCH JACKPOT SEED
GERANIUM AS INFLUENCED BY TYPE OF NITROGEN FERTILIZER
Nitrogen Dry weight N supplied'
fertilizer Shoot Root Plant
2  
Leachate Medium Unaccounted for
Grams Grams Pct. Pct. Pct. Pct.
Ammonium sulfate....................................... 7.9c
3  
2.1c 27d 43a 19b llb
Ammonium nitrate....................................... 14.9a 3.5a 47a 32b 18b 3c
Calcium nitrate.......................................... 14.4a 3.3ab 33c 46a 18b 3c
Urea .................................................. 13.2b 3.3ab 37b 21b 19b 23a
Osmocote .............................................. 13.3b 3.0b 38b 30b 26a 6c
'Sum of medium N at planting and fertilizer N applied (1,124 mg = 100 percent).
2
Shoot and root samples 
combined.
3
Mean separation within columns by Duncan's multiple range test, 5 percent level; values 
followed by the same letter are not statistically different.
[5]
Comparison of Various Controlled-Release
Fertilizers on the Growth
of Ficus benjamina
Linda G. Waterhouse, Kenneth C. Sanderson,
and John C. Williams
Nutrition has a major influence on growth rate, quality, and
longevity of tropical foliage plants. Foliage plant production
research indicates that in most situations, no single source or
level of fertilization yields the best growth. The most com-
mon fertilizers used are water soluble forms; however, slow-
release fertilizers are also used. Slow-release fertilizer facili-
tates larger single applications of fertilizer and reduces luxury
consumption of nutrients, fertilizer application frequency, la-
bor, leaching loss, and soil fixation of nutrients. The purpose
of this study was to examine the effects of several slow-release
fertilizers on the growth and development of Ficus benja-
mina.
Rooted cuttings of Ficus benjamina were potted in 6-inch
standard pots on April 1. Beginning April 16, the plants were
fertilized with Peters 20-20-20 at the rate of 3.4 pounds of N
per 100 square feet per year (50 p.p.m. N-P-K applied at
rates of 8 ounces every 2 weeks) until the experimental fer-
tilizers were applied August 20.
The slow-release fertilizers used included Scott Pro-Grow
25-10-10, Mag Amp 7-40-6, and Osmocote 14-14-14. Experi-
mental treatments are listed in table 2. The slow-release fer-
tilizers were spread uniformly over the medium surface of
the pots. Liquid fertilizer was applied at the rate of 3.4
pounds of N per 100 square feet per year.
TABLE 2. HEIGHT, DRY WEIGHT, VISUAL RATINGS, AND HUNTER COLOR
DIFFERENCE VALUES OF FICUS BENJAMINA RECEIVING
VARIOUS FERTILIZER TREATMENTS
Fertilizer Rate ofPlant Dry Visual Green
source and formulation N/100 height weight ratingcolor
2
sq.source and formulation ft.heght
Lb. In. Grams
Mag Amp 7-40-6.......... 1.8 18.1 18.5 1.0 -4.1
2.4 19.8 22.0 1.3 -5.7
Osmocote 14-14-14........ 1.8 22.3 24.7 2.3 .0
2.4 22.2 26.1 2.2 3.9
Scott Pro-Grow 25-10-10 1.8 20.6 29.6 2.3 2.9
2.4 22.0 32.9 2.8 11.9
Peters Liquid 20-20-20 .... 3.4 22.2 28.3 3.3 13.0
Check................... 16.9 13.8 1.0 -6.2
LSD, 5 percent level ..... 3.6 6.1 .6 8.1
'Rating scale: 4 = a dark green color, full spreading habit, and nonspindly
growth; 3 = medium to light green color and some spindliness; 2 = light
green color and a tall spindly habit; 1 =yellowish green to yellow color, short
plants, thin growth, and nonacceptable plants.
2
Green color determined with a Hunter Color Difference Meter. The
greater the value the more intense the green color.
The medium was a 1:1:1 mixture (by volume) of sand,
sphagnum peat moss, and pine bark. Added amendments
consisted of 0.6 pound dolomite, 0.1 pound Perk (a micron-
trient additive), and 2.5 ounces Aquagro (a nonionic wetting
agent) per cubic yard. The sand and the peat moss were
steam pasteurized before mixing, but the pine bark was not.
Experiments were conducted at Auburn University, Ala-
bama, in a glass greenhouse cooled throughout the summer
by evaporative pads. The plants were maintained under nat-
ural daylight at approximately 2,000 foot-candles. A random-
ized complete block design was utilized with six pots per
treatment and one plant per pot. Height data were collected
at the end of 4 months, with the plant height being measured
from the pot rim to the terminal meristem. Two recently ma-
ture leaves were taken from each plant for the measurement
of green color with a Hunter lab color difference meter.
At the end of the experiment, a visual rating of plant ap-
pearance was made using a rating scale ranging from 1 to 4,
with 1 indicating a stunted and chlorotic plant and 4 a healthy,
dark green plant. After the visual rating, dry weight data
were taken.
The highest rates of each of the test fertilizers produced
the most desirable plants. Most slow-release fertilizer treat-
ments produced plants comparable in growth to plants re-
ceiving liquid fertilizer every 2 weeks. The shortest plants
were produced by the check (no fertilizer) treatment, table 2.
Other treatments were not significantly different. Unfertil-
ized plants produced the least dry weight, table 2; however,
plants receiving Mag Amp at 1.8 pounds of N per 100 square
feet per year did not differ from unfertilized plants in dry
weight. Scott Pro-Grow applied at 2.4 pounds of N per 100
square feet per year produced plants with the darkest green
leaves, whereas Mag Amp-fertilized plants had the poorest
leaf color. Plants receiving Mag Amp or no fertilizer received
similar visual ratings. Scott Pro-Grow fertilizer at 1.8 and 2.4
pounds of N per 100 square feet resulted in plants similar in
appearance to plants fertilized with Peters liquid fertilizer.
Dry weight of plants receiving Scott Pro-Grow 25-10-10 at
the rate of 2.4 pounds of N per 100 square feet was greater
than that of plants receiving Mag Amp and Osmocote at the
rate of 1.8 pounds of N per 100 square feet per year. With the
exception of Mag Amp, plants receiving 2.4 pounds of N per
100 square feet per year produced similar dry weights.
Results of this study reveal that Osmocote and Scott Pro-
Grow controlled-release fertilizers applied at the rate of 2.4
pounds of N per 100 square feet per year were comparable for
growth of Ficus benjamina. Mag Amp, even at 2.4 pounds of
N per 100 square feet per year, produced poor results in this
study. Applications of surface broadcast, controlled-release
fertilizers produced plant growth equal to that obtained with
every-2-week applications of water-soluble liquid fertilizer.
Evaluation of Group IV Snapdragon
Cultivars in Central Alabama
Kenneth C. Sanderson and Willis C. Martin, Jr.
Year-round production of snapdragon has been achieved in
most major producing areas in the United States. Most of the
information on cultivars and scheduling is for production in
greenhouses in the Northern United States or cloth houses in
Florida. Cultivar information and schedules are lacking for
Southern culture. High temperature, high light intensity,
and long photoperiods during Southern summers offer a spe-
cial challenge for snapdragon production. Cultivars have
been bred to do best under high temperature, high light in-
[6]
tensity, and long days. This research was conducted to eval-
uate these cultivars (Group IV) under central Alabama
conditions.
Seedlings of the various Group IV cultivars were sown un-
der mist propagation on May 15 prior to transplanting on July
1 into a steam-pasteurized 1:1:1 (by volume) soil, peat, per-
lite medium or peat-lite medium (Jiffy Mix). Winchester, a
cultivar usually flowered in the late spring or fall, was also in-
cluded in this test. Plants were spaced 16 square inches per
plant and grown single stem. Seedlings were treated at trans-
planting with Terrachlor
TM 
at the rate of 8 ounces per 100 gal-
lons to prevent disease. All crops received Borax at the rate
of 0.5 ounce per 100 square feet to prevent boron deficiency
Fertilization generally consisted of 213 p. p.m. N-P-K every 2
weeks. Plants were grown in a glasshouse with a minimum
night temperature of 620E The glasshouses were air cooled
with a fan and pad system with a thermostat set at 72
0
F dur-
ing experimentation. Plants were grown in light shade (ap-
proximately 10 percent). Monthly mean temperature, solar
radiation, and daylength for Auburn, Alabama, latitude
32034' N., longitude 85'31' W., are shown in table 3.
TABLE 3. MONTHLY MEAN TEMPERATURE, SOLAR RADIATION, AND
DAYLENGTH, AUBURN, ALABAMA, LATITUDE 32034 N.,
LONGITUDE 85031
, 
W.1
Temperature
2  
Daylength,
Month Average Average Solar sunrise to
daily daily radiation
3  
sunset
4
maximum minimum
F OF Langleys Hr:min.
May ........... 84.3 58.5 15911 13:52
June .......... 89.8 65.6 15607 14:13
July ........... 90.9 68.3 14262 14:02
August ........ 90.0 67.7 13650 13:21
'Taken from Auburn University Micro Meterological data.
2
Means for 1941-70.
3
Mean for 1982.
4
Mean calculated from monthly range. Sunrise and sunset are considered
to occur when the upper edge of the disk of the sun appears to be exactly
on the horizon, with normal atmospheric conditions, at zero elevation
above the earth's surface in a level region.
Growth data were taken on 20 plants at harvest, i.e. when
one-third to one-half of the florets were open. Plants were
harvested by cutting stems at the soil line. Data included
date of harvest, plant height and weight, spike length, and
stem strength, table 4. Stem strength was determined by
stripping five plants of all leaves, cutting 20 inches of stem
from directly below the last floret, weighing the stripped
stem sections, and calculating an index of grams per centi-
meter. Top grade snapdragons (averaging a 3.2 quality grade
out of a possible 4.0) have grams per centimeter ratios rang-
ing from 0.17 to 0.22.
Oklahoma produced the tallest plants of any cultivar
tested. Previous tests have shown that 37.8 inches is average
for Group IV snapdragon plant height. Winchester, a culti-
var generally grown in the spring and fall, was the second tall-
est cultivar, followed by Miami. Most of the other cultivars
were below average in height; Tampa, Houston, and Florida
plants were more than a foot shorter than Oklahoma plants.
'Kenneth C. Sanderson and Willis C. Martin, Jr. 1978. Evaluation and
Scheduling of Snapdragon Cultivars. Ala. Agr. Exp. Sta. Bull. 468.
TABLE 4. EVALUATION OF THE PLANT HEIGHT AND WEIGHT, FLOWER SPIKE
LENGTH, STEM STRENGTH, AND FLOWERING TIME OF GROUP IV CULTIVARS
OF SNAPDRAGON FLOWERED DURING AUGUST
Cultivar
Oklahoma ..........
Winchester .........
M iami .............
M obile .............
Alabama ..........
Texas ..............
Tampa .............
Houston ...........
Florida .............
Plant
height
In.
44.7a
2
39.4b
37.4c
35.2d
35.2d
34.3d
31.8e
31.7e
31.6e
Plant
weight
Oz.
1.5a
1.2bc
1.5a
1.0d
1. lcd
.9de
.8e
1.3ab
.9de
Spike
length
In.
9.5a
7.5b
7.6b
6.9cd
6.8cd
7.2bc
6.6d
7.6b
6.5d
Stem Days to
strength' flower
Grams/cm No.
0.012ab 53a
.011bc 48c
.0009cd 46d
.011Obc 45e
.014a 52b
.009bcd 44f
.007d 45e
.008cd 42g
.009bcd 44f
'Higher the reading the stronger the stem.
2
Mean separation within columns by Duncan's multiple range test, 5 per-
cent level; values followed by the same letter are not statistically different.
Oklahoma and Miami plants weighed more than the other
cultivars and were the only cultivars to meet the average
Group IV cultivar plant weight. Texas, Tampa, and Florida
plants produced the least fresh plant weight.
A flower spike length of 8.1 inches is average for a Group
IV cultivar. Oklahoma was the only cultivar in the test to
meet this average. Mobile, Alabama, Tampa, and Florida had
flower spikes an inch or more shorter than average and almost
2 inches shorter than Oklahoma spikes.
None of the cultivars equalled the average stem strength
reading of 0.015 gram per centimeter, however Alabama came
close with a rating of 0.014. Oklahoma was statistically similar
to Alabama in stem strength.
Oklahoma was the latest-flowering cultivar and Houston
was the earliest-flowering cultivar. Considerable variation 
in
flowering time existed among the cultivars.
The research indicates that Oklahoma is a superior Group
IV or summ wering snapdragon. There is a need for new
Group IV cultivars that will grow as well and flower 
at the
same time as Oklahoma.
Chemical Reduction of Induced Petal
Abscission in Geraniums
Roger D. Anderson, Kenneth C. Sanderson, and
John C. Williams
Loss of flower parts (shattering or abscission) is a serious
problem of seedling hybrid geraniums, Pelargonium x hor-
torum. Petal abscission in geraniums is usually due 
to ge-
netics and environmental stress. Cultivars differ in petal
insertion and "easy to shatter" geraniums are characterized
by a region of structural weakness that is absent or less 
evi-
dent in "difficult to shatter" geraniums. Environmental stress
may increase ethylene production which stimulates 
petal abs-
cission. Inhibitors of ethylene synthesis, such as aminoe-
thoxyvinylglycine (AVG), aminoxyacetic acid (AOA), and
silver thiosulfate (STS), might be useful in preventing or at
least reducing petal abscission in geraniums. The objective of
this work was to investigate the use of these chemicals on
petal abscission in geraniums.
Seedling P. x hortorum Jackpot flowers were harvested
from outdoor-grown plants on July 14, 1981. Individual, newly
[7]
opened florets were selected for uniformity and placed in
0.15-ounce vials filled with one of the following solutions: 0.5,
1.0, or 2.0 millimole (mM = 1/1000 of the molecular weight
of the chemical) AVG; 0.1, 0.5, 1.0, or 1.5 mM AOA; and 0.05
percent, 0.1 percent, or 0.5 percent of full strength CT 2000
(a commercial STS formulation 
for pretreatment of carna-
tions). Deionized water was used in each treatment formu-
lation and also served as the control. Florets were kept in
these treatment solutions in a room maintained at 72'F for 12
hours under 40 to 120 foot-candles irradiance. Then, using a
Halby Champ mist blower, 2,000 p.p.m. 2-chloroethylphos-
ponic acid (ethephon) was misted over the top of all florets at
a rate of 2.3 ounces per 100 square feet. The number of florets
abscised was determined before and after ethephon applica-
tion. A floret was considered abscised when one or more pet-
als had fallen.
Flowers treated with STS, AOA, and AVG abscised less
than the check flowers after ethephon treatment. Differences
between treatment concentrations of AOA and AVG were not
significant in this experiment. The STS product, CT 2000,
was effective at 0.1 percent in reducing petal abcission. Re-
sults of the present research agree with recent work by other
researchers which reported that STS and AVG were effective
in reducing abscission in geraniums. The current research
also indicates AOA is effective in reducing petal abscission.
AVG has been found to be too expensive to manufacture and
will not be available for use as a cut flower preservative. AOA
is readily available and relatively inexpensive, however it may
be too toxic to humans to be safely used as a floral preserva-
tive. STS is currently being used commercially on carnations.
Effect of Fungicides on Rooting of
Poinsettia Cuttings
Kenneth C. Sanderson, Willis C. Martin, Jr., and
Leland W. Lee
Poinsettia is prone to fungal infections during propagation.
Fungicides are frequently added to root-inducing powder or
used as drenches to protect poinsettia cuttings from diseases
such as Pythium, Rhizopus, Rhizoctonia, and Thielaviopsis.
Fungicides have been shown to stimulate or inhibit the root-
ing of cuttings. This study investigated the influence of sev-
eral fungicides as basal dips and drenches on the rooting of
poinsettia cuttings. Two experiments considered fungicides
applied to the base of cuttings and one examined fungicide
drenches during rooting.
Experiment 1. Cuttings from field-grown stock plants of
Annette Hegg were propagated October 1, 1981, in coarse
perlite and under mist (3 seconds out of every minute, 8:30
a.m. to 4:30 p.m.) at a minimum night temperature of 70oF
and maximum light intensity of about 5,000 foot-candles. The
basal end of a 5- to 7-inch cutting was dipped to a depth of 1
inch into a commercial rooting compound (Hormodin No. 3,
0.3 percent indolebutyric acids IBA) and then into the fungi-
cide treatment (undiluted commercial formulation of the fun-
gicide). All fungicides shown in table 5, except Subdue, were
TABLE 5. EFFECT OF FUNGICIDES APPLIED TO THE BASE OF ANNETTE HEGG
POINSETrIA CUTTINGS PRIOR TO PROPAGATION UNDER MIST
Fungicide Experiment 11 Experiment 22
rooting score
3  
Rootingcor weight
mg
None, check ............. 3.8a
4  
4.5a 157a
Benlate 50 WP ........... 2.9bc 4.2abc 129abc
Captan 50 WP ........... b3.5ab Not tested
Fermate 50 WP ........... 3.6ab 4.4ab 143ab
Lesan 35 WP ............ 1.6d 3.4c 86cdef
Subdue 25 WP ........... Not tested 4.0a ll4abcd
Terrachlor 75 WP ........ 3.7ab 3.9a 100abcde
Truban 30 WP ........... 2.2cd 3.9a 100abcde
'Cuttings were dipped into Hormodin No. 3 (3 percent indolebutyric acid)
and then dipped into the commercial formulation of the fungicide.
2
Cuttings were dipped into a 0.1 percent indolebutyric-talc rooting powder
containing 5 percent of the commercial formulation of the fungicide by
weight.
3
Rooting scores were: 0 = dead, 1 = no roots or callus, 2 = callused, 3
= light rooting, 4 = medium rooting, and 5 = heavy rooting.
4
Mean separation within columns by Duncan's multiple range test, 5 per-
cent level; values followed by the same letter are not statistically different.
applied in this manner prior to inserting the cutting into the
perlite propagation medium. Untreated or check cuttings
were treated with Hormodin No. 3 only. Four weeks after
propagation (November 12), rooting was evaluated by the fol-
lowing rooting scores: 0 - dead, 1 = no roots or callus, 2 -
callused, 3 = light rooting, 4 = medium rooting, and 5
heavy rooting.
Three days after treatment, the shoot tip of cuttings re-
ceiving Lesan turned black. Cuttings treated with Terra-
chlor, Fermate, and Captan had rooting scores statistically
similar to check cuttings. Benlate, Truban, and Lesan re-
duced rooting, table 5. Plants treated with Truban or Lesan
also showed an increased mortality 4 weeks after propaga-
tion, with 16 percent and 24 percent, respectively, dead.
Check plants showed 8 percent mortality
Experiment 2. Fungicides were incorporated at the rate of
5 percent by weight into a 0.1 percent IBA and talc root-
inducing compound in an experiment conducted in early Sep-
tember. All fungicides shown in table 5 except Captan were
used. The basal 1-inch of Annette Hegg Brilliant cuttings was
dipped into the fungicide-rooting powder treatment. A con-
trol, 0.1 percent IBA and talc, was included. Propagation and
rooting scores procedures were similar to Experiment 1. Root
dry weight was measured by severing the roots from the
shoot and drying at 122?F for 24 hours prior to weighing. The
control and all fungicide treatments, except for Lesan treat-
ment, produced similar rooting scores and root dry weights,
table 5. Rooting of Lesan-treated plants was significantly re-
duced.
Experiment 3. Cuttings of Annette Hegg Topstar and An-
nette Hegg Lady were treated with 0.1 percent IBA rooting
compound prior to placement in 6-inch pots containing per-
lite. The cuttings were immediately drenched with 6 ounces
of a fungicide drench treatment that contained one or two
fungicides, table 6. A water drench was used as a control.
Root dry weights were recorded 5 weeks after drench treat-
ment.
[8]
TABLE 6. DRY WEIGHTS OF POINSETTIA ROOTS TREATED WITH FUNGICIDE
DRENCHES PRIOR TO ROOTING
Fungicide Rate per Dry weight
100 gal. Dry weight
Oz. mg
C ontrol ................................. 129a'
Benlate 50 W P ........................... 8 106a
Captan 50 W P ........................... . 8 89ab
Subdue 25 W P............................ 1 89ab
Truban 30 WP + Captan 50 WP ............ 4 + 4 88ab
Truban 30 WP + Benlate 50 WP ........... 04 + 4 87ab
Subdue 25 WP + Benlate 50 WP ........... 0.5 + 4 75ab
Truban 30 WP + Terrachlor 75 WP ......... 4 + 4 67ab
Truban 30 W P ........................... 8 65ab
Lesan 35 WP + Benlate 50 WP ............ 4 + 4 62ab
Subdue 25 WP + Captan 50 WP ............ 0.5 + 4 60b
Lesan 35 WP + Terrachlor 75 WP .......... 4 + 4 59b
Lesan 35 WP + Captan 50 WP ............. 4 + 4 57b
Subdue 25 WP + Terrachlor 75 WP ......... 0.5 + 4 55b
Lesan 35 W P. ............................ 8 47b
Terrachlor 75 WP ........................ 8 37b
'Mean separation within columns by Duncan's multiple range test, 5 per-
cent level; values followed by the same letter are not statistically different.
Single fungicide drenches of Benlate, Captan, 
Subdue,
and Truban produced root dry weights similar to the control,
table 6. Combination drenches ofTruban + Captan, Truban
+ Benlate, Subdue + Benlate, Truban + Terrachlor, and
Lesan + Benlate gave root dry weights similar to the control.
Root dry weight was reduced where other fungicides or fun-
gicide combinations were used as drenches.
The use of fungicides during propagation is an essential
cultural practice in the production of crops such as poinset-
tia. Results of these tests show that caution must be used
when selecting a fungicide since some fungicides may reduce
rooting. In all test procedures, Lesan (Experiments 1, 2, and
3) reduced rooting, whereas Fermate (Experiments 1 and 2),
Captan (Experiments 1 and 3), and Subdue (Experiments 2
and 3) did not affect root development. Benlate and Truban
reduced rooting when used at high concentrations as a dip
treatment (Experiment 1). Selecting a fungicide treatment for
use during poinsettia propagation requires evaluation of the
disease control desired and the fungicide effects on root de-
velopment.
Tolerance of Four Potted Chrysanthemum
Cultivars to Dursban
Kenneth C. Sanderson and Willis C. Martin, Jr.
Agromyzid leafminers are serious and persistent pests on
chrysanthemum (Chrysanthemum morifolium). Crop quality
depends on maintaining low leafminer populations, but most
growers find it difficult to achieve satisfactory control of this
pest with currently recommended insecticides. Dursban is
effective against third stage larvae of Liriomyza trifolii, one
of the three leafminer species that damage chrysanthemums.
However, the safety (phytotoxicity) of Dursban on many chry-
santhemum cultivars is not known. The purpose of this study
was to examine the safety of Dursban applied as a spray and
drench on four potted chrysanthemum cultivars.
Rooted cuttings of the chrysanthemum cultivars Bright
Golden Yellow Princess Anne, Loyalty, Spirit, Sunlight, and
Yellow Mandalay were planted four cuttings per pot into 6-
inch azalea pots on January 29. Two media were used: Pro-
mix and 1:1:1 (by volume) soil, sphagnum peat moss, and per-
lite medium. The soil, sphagnum peat moss, and perlite me-
dium was amended with 6 ounces of dolomitic limestone and
1 ounce of single superphosphate per cubic foot. Plants were
pinched 2 weeks after potting. Dursban treatments were ap-
plied 4 weeks after planting. Sunlight plants were grown as
"spray" types with the center flower bud being removed at
disbudding. Lateral buds were removed on the other culti-
vars. Supplementary incandescent light was provided from 10
p.m. to 2 a. m. each night starting at transplanting and ending
at pinching, except Bright Golden Yellow Princess Anne
plants received i week less lighting. Fertilization consisted of
weekly applications of Peters liquid 20-20-20 at the rate of 213
p.p.m. N-P-K. Experimental treatments consisted of Durs-
ban 6E applied at three rates as a drench and one rate as a
spray. Application rates were adapted from the manufactur-
er's recommendation for use of Dursban on turf. DuPont
Spreader Sticker was added to the spray at the rate of 1.3
ounces per 100 gallons. Data on date of flowering, plant
height, plant spread, and flower number were recorded when
two-thirds of the flowers were open.
Visible symptoms of toxicity were observed only on Sunny
Mandalay, which developed a temporary chlorosis and small
leaves when sprayed with 10 ounces per 100 gallons Dursban
sprays. Cultivars flowered in the following order: check (no
treatment), 5 ounces per 100 gallons drench, 10 ounces per
100 gallons drench, 20 ounces per 100 gallons drench, and 10
ounces per 100 gallons spray. The effect of Dursban on the
height of Loyalty and Spirit was inconsistent, table 7. Differ-
ences in plant spread were not significant; however, the 5
ounces per 100 gallons drench usually produced plants with
the greatest spread. The number of flowers per plant on
Sunny Mandalay plants was reduced by the high rate (20
ounces) Dursban drench treatment, table 7. Media did not in-
teract with Dursban treatment to affect chrysanthemum
growth or phytotoxicity (data not shown).
These results show that Dursban drenches can be used
safely on certain chrysanthemum cultivars, and this has been
confirmed in other tests. A granular formulation of Dursban
(Lorsban 15G) has received labeling for broad spectrum soil
insect control on agronomic crops and should be tested on
chrysanthemums as an alternative method of application.
TABLE 7. THE EFFECT OF DURSBAN APPLICATION TREATMENTS ON THE
HEIGHT OF LOYALTY AND SPIRIT AND FLOWER NUMBER OF YELLOW
MANDALAY CHRYSANTHEMUMS
Dursban per 100 gallons Height Flowers per plant
Dursban per 100 gallons Loyalty Spirit Sunny Mandalay
In. In. No.
None ..................... 12.0ab 8.9b 5.9a
5 oz. drench................ b12.lab 10.Oa 5.9a
10 oz. drench............... 12.3a 9.8a 5.5a
20 oz. drench .............. 11.2c 9.5a 4.5b
10 oz. spray ................ 11.4bc 8.8b 5.6a
'Mean separation within columns by Duncan's multiple range test, 5 per-
cent level; values followed by the same letter are not statistically different.
[9]
V
WOODY ORNAMENTALS
Response of Woody Plants to Timing of
Supplemental Nitrogen Applications
Gary J. Keever and Gary S. Cobb
Optimum growth of woody plants and efficient use of ni-
trogen fertilizer depend on the correct timing of fertilizer ap-
plications. Many woody plants exhibit cyclic or episodic
growth during the growing season, i.e. spring or spring and
late summer flushes with little growth during early to mid-
summer. Previous research by the authors has shown that ex-
cellent quality woody plants can be grown when a slow-re-
lease fertilizer is used in combination with supplemental
liquid N fertilization. This study was initiated to evaluate
four supplemental N fertilization schedules (three liquid, one
granular) and one incorporated slow-release fertilizer treat-
ment.
Uniform liners of Ilex crenata Compacta, Euonymusja-
ponica Microphylla, and Rhododendron x Hino-crimson
were potted in March, 1983, in 1-gallon plastic containers. A
milled pine bark medium was amended with 5 pounds do-
lomitic limestone + 2 pounds superphosphate (0-20-0) + 2
pounds gypsum + 1.5 pounds Micromax + 10 pounds Os-
mocote 17-7-12 per cubic yard except for one treatment which
had a 15-pound rate of Osmocote with no supplemental N.
Euonymus and holly were grown in full sun and azalea in 47
percent shade. Supplemental N treatments included six
weekly liquid fertilizations in the spring, six weekly liquid
fertilizations in the spring plus six in the fall, weekly liquid
fertilizations throughout the growing season, and surface ap-
plications of granular 12-6-6 (1 teaspoon per pot) spring and
fall. Liquid fertilization rate was 300 p.p.m. N from ammo-
nium nitrate.
In fall 1983, plants of all species given supplemental N in
spring only were lighter in color compared with other treat-
ments. This suggests plant uptake from the 10 pounds per cu-
bic yards of incorporated Osmocote alone was not sufficient to
maintain optimum foliar color throughout the first growing
season.
Top dry weight of holly was lowest when supplemental N
was applied in spring only; dry weights did not differ among
other treatments, table 8. Similar growth of all species when
TABLE 8. EFFECTS OF FERTILIZER SCHEDULING ON
GROWTH OF ILEX CRENATA COMPACTA
Liquid' Granular, Osmocote
Item 
Spring Spring 
spring Os17-7-12,te
Spring and through and
Top dry weight (g) ... 93.4b2 121.0a 121.6a 117.2a 119.4a
Growth index
3 
....... 43.3b 47.2ab 47.6ab 49.7a 49.0a
'300 p.p.m. N from NH
4
NO to supplement Osmocote 17-7-12 (10
pounds per cubic yard).
'Mean separation within rows by Duncan's multiple range test, 5 percent
level; values followed by the same letter are not statistically different.
3
Growth index = (height + width + width) + 3.
given supplemental N in spring through fall and spring plus
fall suggests that supplemental 
liquid N is more efficiently
utilized if applied when plants are actively growing. Growth
index was less with spring only supplemental N compared
with the granular and the 15-pound Osmocote treatments.
With euonymus and azalea, dry weights or growth indices
did not differ among treatments (data not shown). Holly is
often considered a "heavy feeder," while euonymus and azalea
are not. These results suggest supplemental N is needed with
heavy feeders when Osmocote 17-7-12 is incorporated at the
lower end of the generally accepted range of 10-15 pounds per
cubic yard. While the 15-pound Osmocote rate resulted in
growth of holly similar to the 10-pound rate plus spring/fall
supplements, the use of supplements provides greater control
of growth and soluble salts during hot summer weather when
the release rate of Osmocote increases with the temperature.
Comparison of Fertilizer Application
Methods for a Single Component
Growth Medium
Gary S. Cobb
Blending of media and application of granular fertilizers
are two labor-intensive tasks that should be done accurately
and consistently. Slow-release fertilizers have reduced the
frequency and application costs of primary nutrients, but
mixing of multicomponent media and preplant incorporation
of primary, secondary, and/or micronutrients is common prac-
tice among nurserymen. Most growers blend two or more
components (bark, peat, perlite, shavings, etc.) with several
fertilizers (N-P-K, dolomitic limestone, micronutrients, gyp-
sum, etc.) to produce their growth media.
Several years of research and limited commercial trials
have demonstrated that a milled pine bark (with the appro-
priate particle size distribution) is a suitable growth medium
without additional medium components. Use of a single com-
ponent growth medium eliminates the need for blending ex-
cept to add the preplant incorporated fertilizers. If all
fertilizers are applied by means other than incorporation,
then the labor, equipment costs, and inconsistency associated
with blended media would be eliminated. This study was in-
itiated to compare fertilizer application methods for a pine
bark growth medium.
Uniform liners of Ilex crenata Rotundifolia, Ligustrum x
vicaryi, Gardenia jasminoides Radicans, and Rhododendron
x Amy were potted in 3-quart (trade gallon) containers May
10, 1984, in a 100 percent milled pine bark growth medium.
Fertilizers were applied to all treatments and species at a rate
equivalent to 6 pounds dolomitic limestone, 2 pounds gyp-
sum, 1.5 pounds Micromax, and 12 pounds Osmocote 17-7-
12 per cubic yard. Three fertilizer application methods were
compared: preplant incorporation, surface application (top-
dress), and dibble application (where the fertilizers are
[10]
TABLE 9. EFFECTS OF FERTILIZER APPLICATION METHOD ON GROWTH OF FOUR WOODY ORNAMENTALS
IN A 100 PERCENT MILLED PINE BARK GROWING MEDIUM
Fertilization Growth Shoot dry Root
Crop method' index2 weight rating
3
Grams
Ilex crenata Rotundifolia .......................... Incorporated 32.4 17.6ab 3.7
(Japanese holly) Surface appl. 30.4 20.6a 4.0
Dibbled 30.Ins
4  
15.6b 3.7ns
Liqustrum x vicaryi .......................... Incorporated 51.6b 19.0b 4.3b
(Golden privet) Surface appl. 55.Ob 23.0ab 4.7ab
Dibbled 62.2a 26.la 4.9a
Gardenia jasminoides ............................. Incorporated 54.7a 55.5 5.0
Radicans Surface appl. 51.9b 55.0 5.0
(Dwarf gardenia) Dibbled 52.0b 54.6ns 5.0Ons
Rhododendron x Amy ............................. Incorporated 36.3a 24.7a 3.8a
(Amy azalea) Surface appl. 37.4a 29.1la 3.9a
Dibbled 33.7b 17.4b 2.7b
'Equivalent to 12 pounds Osmocote 17-7-12 (18 grams per pot) + 6 pounds dolomitic limestone (9 grams per pot) + 2 pounds gypsum (3 grams per pot)
+ 1.5 pounds Micromax (2.3 grams per pot) per cubic yard.
2
Growth index = (height + width + width) + 3, with measurements 
taken in centimeters.
3
Root development was rated on a scale of I to 5 where 1 = few roots penetrating to the outside of the 
root ball and 5 = dense coverage of entire root ball.
4
Mean separation within species and columns by Duncan's multiple range test, 5 percent level; 
values followed by the same letter are not statistically
different. ns = no statistical difference among treatments.
placed directly under the liner). All crops were grown in full
sun (except Amy azalea in 47 percent shade); irrigation was
applied as needed by overhead impulse sprinklers.
After 5 months, growth index and root rating of holly were
similar regardless of application method, but shoot dry
weight of surface-fertilized plants was greater than with dib-
ble-fertilized plants, table 9. With ligustrum, growth index
was greatest with dibble fertilization. Shoot dry weight and
root rating of ligustrum were greater with dibble fertilization
than with preplant fertilizer incorporation. Shoot dry weight
and root rating of gardenia were similar with all treatments,
but growth index of plants fertilized by preplant incorpora-
tion was greater than with the other fertilization methods.
With Amy azalea, preplant incorporation and surface appli-
cation of fertilizers resulted in greater growth index, shoot
dry weight, and root rating than dibble fertilization.
Although growth response varied somewhat among treat-
ments and species, all crops were produced successfully re-
gardless of fertilizer application method. In general, fast-
growing species responded better than slower-growing spe-
cies to dibble fertilization. This is consistent with previously
reported data and probably reflects that the roots of slower-
growing plants take longer to penetrate the lower portion of
the container where dibble-applied fertilizers are in greatest
concentration. Surface application compared favorably to pre-
plant incorporation for all species. These results suggest that
fertilization of a single component growth medium (pine
bark) can be successfully accomplished with surface applica-
tion, dibble application (except perhaps with slow-growing
crops), or preplant incorporation of the entire fertilizer pack-
age. Surface or dibble fertilizer application of a single com-
ponent medium would eliminate the need and costs of
blending fertilizers and media components and ensure
amendment uniformity among individual pots. Selection of
the appropriate method should be based on costs and adapt-
ability to existing production practices.
See color plates numbers 1-3.
Response of Four Woody Ornamentals to
Superphosphate Incorporation and
Osmocote Placement
Gary S. Cobb and Clyde E. Evans
In the production of container-grown woody ornamentals,
superphosphate is frequently recommended for preplant in-
corporation into the media. The basis for this recommenda-
tion is questionable in view of recent studies showing that
phosphorus from incorporated superphosphate leaches read-
ily from pine bark media. Because of phosphate mobility in
bark media, placement of a complete fertilizer may be im-
portant. This study was initiated to evaluate four woody or-
namentals grown with and without preplant incorporation of
regular superphosphate (0-20-0). A complete slow-release
fertilizer was included and its placement investigated.
Uniform liners of Cotoneaster rotundifolius, Ilex crenata
Helleri, Rhododendron x Hino-crimson, and Rhododendron
x Delaware Valley White were potted April 15, 1982, into 1-
gallon containers using a milled pine bark-sandy loam (7:1, by
volume) medium amended with 8 pounds dolomitic lime-
stone, 2 pounds gypsum, and 1.5 pounds Micromax per cubic
yard. Fertilizer treatments included preplant incorporation of
superphosphate (0 and 2 pounds per cubic yard) factorialized
with Osmocote placement (incorporation and surface appli-
cation, 10 pounds per cubic yard). Cotoneaster and holly were
grown in full sun, while azaleas were grown in 47 percent
shade. Plants were irrigated as needed by overhead impulse
sprinklers.
All species responded similarly, thus only data for Hino-
crimson azaleas are presented. After 6 months there was no
difference in plant growth (growth index and shoot dry
weight); root rating; leaf tissue nitrogen (N), phosphorus (P),
and potassium (K); and growing medium N, P, K, and pH for
Hino-crimson azaleas grown either with or without preplant
incorporation of regular superphosphate (data not shown).
[11]
TABLE 10. EFFECT OF OSMOCOTE PLACEMENT ON GROWTH INDEX', SHOOT
DRY WEIGHT, ROOT RATING, LEAF PRIMARY NUTRIENT LEVELS, AND
MEDIUM pH WITH CONTAINER-GROWN HINo-CRIMSON AZALEAS
Item 
Osmocote 
17-7-12, (10 
lb./yd.
3
)
Incorporation Surface application
Growth index ............ 46a
2  
43b
Shoot dry weight (grams) .. 53a 43b
Root rating3 
. . . . . . . . . . . . .  
3.1a 1.8b
Leaf tissue
Pct. N1................ 1.6b 2.0a
Pct. P ................ .15b .17a
Pct. K................. .61b .88a
Medium pH ............. 5.6a 5.2b
'Growth index = (height + width) + 2, with measurements taken in
centimeters.
2
Mean separation within rows by Duncan's multiple range test, 5 percent
level; values followed by the same letter are not statistically different.
3
Root development was rated on a scale of 1 to 4 where 1 = few roots
penetrating to the outside of the root ball and 4 = dense coverage of entire
root ball.
Plants fertilized with a surface application of Osmocote in-
itiated a growth flush and became dark green in color quicker
than those grown with the fertilizer incorporated. Perhaps
liner roots were in closer proximity to surface-applied fertil-
izer. However, at the end of the growing season, plant growth
and root rating were greater when Osmocote was incorpo-
rated, table 10. These data and observations suggest fertilizer
placement influences nutrient availability. Leaf tissue N, P,
and K were higher in plants fertilized with a surface appli-
cation, possibly reflecting a growth dilution in the larger
plants produced with incorporated fertilizer. Medium pH
was higher when Osmocote was incorporated.
This study showed no increase in leaf tissue P, shoot
growth, or root development when superphosphate was in-
corporated into the growth medium. While adequate P was
provided by fertilization with Osmocote 17-7-12 at 10 pounds
per cubic yard, placement influenced plant growth and root
development.
Effect of Trickle Irrigation, Nitrogen Rate,
and Method of Nitrogen Application on
Field-Grown Japanese Holly
D. Joseph Eakes, Charles H. Gilliam, Harry G. Ponder, and
Clyde E. Evans
Increased production costs have caused nurserymen to
seek more effective production practices. One way to pro-
duce higher quality plants in a shorter period is with irriga-
tion. However, irrigation is generally not considered
economical or practical for field-grown nursery stock because
conventional irrigation practices create heavy demands on
available water, and irrigation systems are costly to install and
maintain. An alternative is trickle irrigation, which is a more
cost-effective method of irrigating field-grown nursery stock.
Trickle irrigation is the daily maintenance of at least 25 per-
cent of a plant's root system under adequate moisture condi-
tions. Trickle uses 60 to 70 percent less water than overhead
[12]
irrigation because water is applied directly to the root zone.
Disease and weed problems are reduced since neither the fo-
liage nor the area between rows and plants is wetted. Re-
search has indicated that restricting water to a specific area
directly around the plant produces a more desirable compact,
fibrous root system. Other possible advantages of trickle ir-
rigation for nursery producers are extended planting season
and the injection of fertilizer, preemergent herbicides, and
systemic pesticides reducing labor requirements.
The objectives of this study were to determine the effects
of trickle irrigation, four nitrogen (N) rates, and three meth-
ods of N application on field-grown Compacta Japanese holly.
Growth, foliar nutrient content, livability, and visual ratings
were measured.
On April 30, 1982, uniform liners of Compacta Japanese
holly were planted in a Marvyn loamy sand soil at Auburn
University. Plants were spaced 3 feet within rows and rows
were 3 feet apart. Liners were watered at planting, fertilized
according to soil test recommendations except for N (120
pounds of N per acre was recommended), and thereafter
maintained according to normal nursery practices.
Three methods of applying ammonium nitrate (NH
4
NO
3
)
were evaluated at four N rates each: broadcast, broadcast
with trickle irrigation, and injection into the irrigation sys-
tem. The four N rates used were 30, 60, 120, and 240 pounds
per acre split equally among four applications during each
growing season. These rates were based on Auburn Univer-
sity's general recommendation of 120 pounds N per acre for
field-grown nursery stock.
Trickle irrigation lines of 1/2-inch inside diameter black
plastic pipe were run to two-third of the plants (192) in the
study. A Rain Bird J10 pressure-compensating emitter (1 gal-
lon per hour) was installed in the trickle irrigation line at the
base of each plant. At the head of half of the irrigation lateral
lines, fertilizer was injected by hydraulic displacement of fer-
tilizer from a small plastic container. The fertilizer injection
system consisted of a gate valve, two microtubes held in place
by brass grommets, and a fertilizer solution container. The
gate valve created a pressure differential in the line forcing
water into the solution container through a long microtube
running from the main line below the gate valve. As water
was forced through the tank, fertilizer was displaced by con-
tinual dilution of the fertilizer solution in the tank.
Daily rainfall and net evaporation from a class A pan were
recorded throughout the 2-year study. Water was applied
when net evaporation reached 1/2 inch or greater at the rate of
50 percent replacement of net evaporation. The system was
operated from May to October of each year.
Irrigated vs. Nonirrigated. Holly growth significantly in-
creased with trickle irrigation. Twelve weeks after initiation
of the study, irrigated hollies had produced more new growth
than nonirrigated hollies. Differences increased throughout
the duration of the study. Root and shoot dry weights for ir-
rigated hollies were double those of nonirrigated hollies after
each growing season, table 11. The largest root increase for
TABLE 11. EFFECTS OF TRICKLE IRRIGATION AND N RATES ON GROWTH OF COMPACTA JAPANESE HOLLY
Root ShootLivability
Treatment 
rowth index 
dry weight 
dry weight
1982 1983 1982 1983 1982 1983 1982 1983
Grams Grams Grams Grams Pct. Pct.
Irrigation rate
2
0% net evaporation ................ 10.6 26.7 8.4 62.4 14.4 128.6 76.0 
55.2
50% net evaporation ................ 15.1 34.0 19.2 126.8 32.2 202.0 
100.0 86.6
N rate (lb./acre)
30 ............................... 12.7 29.9 13.4 85.2 24.1 155.4 91.6 77.1
60 ............................... 12.6 32.0 14.8 106.4 22.3 176.7 
93.8 72.9
120 .............................. 13.4 31.9 13.5 96.5 25.6 
161.9 83.3 66.7
240 .............................. 13.9 31.7 13.6 90.5 21.3 
167.2 83.3 66.7
'Growth index = (height + weight + width) + 3. The initial growth index, taken at planting, was subtracted from subsequent 
measurements taken in
late fall of 1982 and 1983.
2
All differences significant at 1 percent level. There was no significant effect as a result of N rate or N rate x irrigation rate.
the irrigated hollies over the nonirrigated hollies was inside
an 8-inch diameter root ball. Both primary and fibrous roots
were increased by trickle irrigation in this 8-inch root ball.
Fibrous roots were increased threefold for irrigated hollies
over nonirrigated hollies. Trickle-irrigated plants should
transplant more successfully due to enhanced root growth,
especially of fibrous roots.
Holly survivability increased with trickle irrigation. Irri-
gated plants had 24 percent greater survivability the first
year and 31 percent greater the second year than nonirrigated
ones. Nonirrigated holly losses occurred mostly in the winter.
A visual inspection in the fall of the first year revealed non-
irrigated plants to have more chlorosis and dieback. This in-
dicates that nonirrigated plants were under greater stress
entering cold weather.
Method of N Application. Plants receiving surface-ap-
plied N had only slightly greater growth than those receiving
injected N by the end of the 2-year study. No differences were
found in visual rating, dry weights of roots and shoots, liva-
bility, and foliar nutrient content with method of N applica-
tion. However, by injecting the fertilizer, less fertilizer was
used because less area was fertilized, and less labor was re-
quired. Therefore, injection of N fertilizer is an effective
method of fertilizing field-grown nursery stock.
N Rate. Plant N content increased as applied N rate in-
creased regardless of method of application or irrigation rate.
However, N rate had little effect on growth, livability, or
visual rating. Nitrogen applied at 60 pounds of N per acre
produced as high a quality plant as higher N rates, indicating
lower N rates are adequate for production of Japanese holly.
Many practical and economical ideas can be found in these
results. Injection of fertilizer into a trickle irrigation system
can produce high quality plants while using less water, fer-
tilizer, and labor than conventional field nursery practices.
See color plate number 4.
Container Growth Medium Temperature
as Influenced by Moisture Content
Gary J. Keever and Gary S. Cobb
Optimum growth medium temperature for root and shoot
growth of many plants is between 68'F and 86'E Outside this
temperature range, plant growth is reduced with plant injury
or death often occurring below 23oF or above 104E It is not
uncommon for temperatures in unprotected containers dur-
ing the summer and winter months to exceed these extremes.
Water for irrigation, whether from ponds, wells, or municipal
sources, is generally cooler than air and container medium
temperatures during the summer months and warmer during
the winter, so its use may lessen temperature extremes in
containers. This study was initiated to determine the influ-
ence of water in a container medium on medium temperature
when air temperature was varied.
Milled pine bark with a bulk density of 0.26 gram per cu-
bic centimeter was divided into four samples using a Hum-
boldt sample splitter. One sample was air-dried at 68
0
F for 1
week. A second sample was submerged in water under 21
inches mercury vacuum for 72 hours to insure medium sat-
uration and then allowed to drain (sample at container ca-
pacity). The two remaining samples were brought to
intermediate moisture levels by syringing them with water,
mixing, and placing them in sealed containers for 7 days.
Moisture content on a volume basis was 2.7 percent for the
air-dried sample, 23.2 percent and 35.2 percent for the in-
termediate samples, and 55.3 percent for the sample main-
tained at container capacity
Three 1-quart black plastic pots were filled with pine bark
medium at each moisture level, and individually enclosed in
plastic bags to prevent desiccation. A thermocouple was in-
serted through the plastic bag into the center of each pot to a
2-inch depth. Pots were randomized in a freezer, brought to
3.2
0
F (-16
0
C), then removed to a 68
0
F (20
0
C) environment.
Temperature was monitored every 30 minutes until container
medium reached ambient air temperature. Pots were again
placed in the freezer and temperature monitored until the
medium reached 10.4?F (-12'C).
[13]
12 15 18
FIG. 1. Temperature versus time for pine bark medium of different
moisture content when warmed to 68
0
F (20
0
C).
Container medium temperature increased rapidly to about
59
0
F (15'C) in the air-dried samples and to 32?F (0OC) at the
three higher moisture levels, figure 1. As moisture content
increased, container medium temperatures remained at the
freezing point longer, reflecting the high heat of fusion (80 ca-
lories per gram) needed to change ice in the medium to
water. Above 32
0
F (0
0
C), medium temperature rose slower in
samples with higher moisture content. This may be explained
by the high specific heat of water (1 calorie per gram), about
5 times as much heat to raise the temperature of a unit vol-
ume of water 1.8
0
F (1C) as is necessary to raise the temper-
ature of a unit of soil. Because the growth medium samples
studied were composed of different ratios of organic compo-
nents to water, heat capacities would be between those for
water and oven-dried medium. Differences among treat-
ments may have been greater if samples had been unsealed,
due to a more pronounced evaporative cooling effect at the
higher moisture levels. As temperature of all medium groups
approached the maximum, the rate of change decreased be-
cause of the small temperature differential between medium
and ambient air.
Temperature,* F
72 -
o 2.7% moisture
A 23.2% moisture
0 35.2% moisture
9
-4 I I I I I I
0 3 6 9 12 15 18
Time, hr.
FIG. 2. Temperature versus time for pine bark medium of different
moisture content when cooled to 10
0
F (-12
0
C).
Temperature, 0F
72
59 -
46
34 L
[14]
21 0 27
A 23.2%
9 035.2%
55.3/
-4 [ I 
I 
1
0 3 6 9
Time, hr.
Similar trends were observed in medium temperature
when the four groups were cooled from 68?F (20
0
C) to 10.4F
(-12'C), figure 2. Air-dried samples dropped rapidly to
21.10F (-6
0
C) due to the low moisture content of the medium,
and more slowly to 10.4
0
F (-12
0
C) due to a small difference in
medium and air temperatures. Samples with higher moisture
content decreased more slowly to 32?F (0
0
C), again due to the
high specific heat of water. With increasing moisture content,
container growth medium remained at the freezing point
longer. Due to water's high heat of crystallization (80 calories
per gram) that was released when water solidified into ice,
the temperature within the container did not fall below the
freezing point as long as any unfrozen liquid remained, nei-
ther did it rise above the freezing point as long as the medium
contained ice.
Knowledge of water's response to changes in ambient tem-
perature is essential in utilizing it to effectively moderate
growth medium temperature during container production.
Due to water's unique properties, maintaining a high con-
tainer water content during short periods of temperature ex-
tremes reduces growth medium temperature fluctuations
and lessens temperature extremes, thus reducing the poten-
tial for root injury.
Irrigation Scheduling Effects on Container
Temperatures and Plant Growth
Gary J. Keever and Gary S. Cobb
High temperatures within container growth media during
the summer months have been shown to reduce root and
shoot growth. Cultural practices which reduce high medium
temperatures include use of reflective containers, non-reflec-
tive bed mulches, overhead shade, and reduced pot spacing.
Another cultural practice which may reduce high medium
temperatures in containers is irrigation scheduling. The ob-
jective of this study was to evaluate the effects of irrigation
scheduling and syringing on growth medium temperature
and plant growth.
Uniform Hershey's Red azalea liners were potted into 1-
gallon containers of amended pine bark. Plants were grown in
full sun and irrigated daily as outlined in table 12. All treat-
ments received the equivalent of 0.5 inch of water per acre
per day; syringing distributed an additional 0.2 inch of water
per acre per day.
Maximum daily growth medium temperatures exceeded
maximum air temperature with all irrigation schedules; how-
ever, there were differences among treatments, figure 3.
Maximum growth medium temperature was lowest (95oF)
when daily irrigation was split with 30-minute applications at
10 a.m. and 3 p.m. Maximum growth medium temperatures
averaged 96
0
F with the 1 p.m. irrigation, 102?F with 8 p.m.
irrigation, and 103?F with 9 p.m. irrigation + syringing.
Growth medium temperatures were depressed for 1 to 3
hours when plants were irrigated during the day. Day irri-
gations (10 a.m., 1 p.m., and 3 p.m.) depressed maximum
canopy temperatures an average of 8?F; the effective depres-
sion was for 2 to 3 hours, figure 4. Syringing reduced the max-
TABLE 12. EFFECTS OF IRRIGATION SCHEDULE ON GROWTH INDEX, Top DRY WEIGHT, RELATIVE ROOT RATING, AND FOLIAR NUTRIENT LEVELS OF
RHODODENDRON HERSHEY'S RED
Daily Growth Dry RelativeLeaftissue
irrigation index' weight root rating
2  
N P K
schedule
Grants Pct. Pct. Pct.
8 p.m., l hr. .............................. 27.8d3 42.5bc 3.2b 1.8 .18 .59
1 p.m., Ilhr................................ 32.6b 46.7ab 3.8a 1.8 .17 .63
10 a.m. + 3p.m., 30min. each................ 34.2a 48.6a 3.4b 1.5 .20 .50
9 p.m. + 2'/2 mm. hourly syringing,
9 a.m. -5 p.m.............................. 31.lIc 41.l1c 3.2b 1.4 .17 .46
'Growth index = (height + width + width)- 3, with measurements taken in centimeters.
2R1elative root rating: 1 poor, 4= coverage of entire root 
ball surface.
3
Mean separation within columns by Duncan's multiple range test, 5 percent level; values followed by the same letter are not statistically different.
imum canopy temperature by 2 to 3'F compared with 8 p.m.
irrigation, while air temperature closely paralleled the 8 p. m.
treatment.
Shoot growth as indicated by top dry weight and growth in-
dex was greatest with split irrigations (10 a. m.1/3 p.m.), fol-
lowed by 1 p. m. irrigations, table 12. Top growth was similar
with plants irrigated at 8 p.m. and 9 p.m. + hourly syring-
ing. Relative root rating was highest with 1 p.m. irrigation
and similar among other irrigation schedules. Foliar N was
40
35
30
25
20
12
o. M.
2 4 6 8 10 12
p.m.
less with split 10 a.m./3 p.m. and hourly syringing treat-
ments, which may indicate a growth dilution effect with split
applications or greater foliar nutrient leaching with both
treatments.
Reduced maximum growth 
medium and canopy tempera-
tures, reduced duration of high temperature, and increased
top and root growth support the utilization of day irrigation.
Hourly syringing offered no benefit except a slight cooling of
the canopy
105
100
95
90
85 ?
80g
75
70
65
2 4 6 8 10 12
v. M.
Time of day (hr.)
FIG. 3. Growth medium temperature patterns within a black pot on a white mulch, as influenced by irrigation schedule. 
Values are the means
of 5 clear days in August 1984.
[15]
U-
0
...
4-.
0
E
-~ N.
-'-
Y' N
A : Z ;
:
,
. L - -I>
i s
(1) Plants with fertilizer incorporated (left), surface applied (middle), and 
dibbled (right). (2) Dibbling. (3)
Dibbled fertilizer. (4) Irrigated Japanese holly. (5) Effects of severe 
shoot pruning (left) in comparison with
no shoot pruning (right). (6) Hershey's Red azalea grown in 3-inch 
deep x (I. to r.) 8-inch, 6-inch, and 4-inch
7:... ; wide pots. (7) Microphylla euonymus grown in 12-inch 
deep x (I. to r.) 8-inch, 6-inch, and 4-inch wide pots.
(8) Variegated pittosporum and (9) fatsia following 3 months in an interior environment under 
three produc-
tion light levels. Cornus
florida cultivars: (10) Bay
Beauty, (11) First Lady,
and (12) Catawba. (13) Re-
gal Red crapemyrtle.
Sun - 17
71%
Cj 177
)q-7.
7.l-
'N
r .s
.3
* -:
-a
13
ar
0*
;i-.
i ~ ;&-; :<
-;
~i ~
~i_ .
A ~7 Tr1
a4 $iimq
4 4w
er Ikh.
I,~
'--A,
72
4r
9
4 t 2-
1
c- :
r .-- ,
C ---
c-& ;:~-~
4I
2 .-
L
*2 i .
2' '~ a
I, .2
* -~ ., ~ ~-A. a
7]
S.
-VT
t
L L
\ ': V.
t
. 5
a,
4!
I "I
t.I~3
,i10t.
14
$
N'
S),ym)ptoms of Entomosporium leaf spot on photinia. (15)
nptoms of anthracnose on euonymus. (16) Control of black
,t on roses with weekly applications of Daconil 2787 com-
red with (17) unsprayed plants. Symptoms 
of Thielaviopsis
on (18) Nellie R. Stevens holly and (19) Japanese holly. (20)
Pseudomonas leaf spot and (21) bacterial leaf spot on south-
ern magnolia. (22) Heavy residue accumulation of Vendex o:n
V-14 Glory poinsettia. (23) Diazinon Ag 500 phytotoxicity on
foliage of V-14 Glory poinsettia. (24) Ornalin phytotoxicity :
foliage of V-14 Glory poinsettia. (25) Daconil 2787 Flowar -
phytotoxicity on bracts and residue on foliage of V-14 Glo b
poinsettia.
it
/ ~ -r 4
'N -
.2.
o
V
r
~i -;
V
C)
0
Ii.
E
0
I-
105
100
95 L.
o
0
80
h._
85
E
1
I-
80
75
70
12 2 4 6 8 IO 12 2 4 6 8 10 12
a.m. p.m a.m.
Time of day (hr.)
FIG. 4. Canopy temperature patterns within a black pot on a white mulch, as influenced by irrigation schedule. Values are the means of 5 clear
days in August 1984.
Effects of Pruning on Root and Shoot
Growth of Ornamentals
Charles H. Gilliam and Gary S. Cobb
In commercial nurseries, an accepted practice is to pro-
duce rooted cuttings (liners) during the spring and summer,
and then to pot them into larger containers the following year.
Stepping-up into larger containers begins during spring and
continues throughout the summer. Most of the stepping-up
into larger containers occurs in late spring and summer due
to the time requirements associated with shipping orders
during early spring. Liners held in small pots become leggy
and at potting are normally pruned severely to develop a com-
pact plant. While the obvious effects of severe shoot pruning
(numerous new shoots producing a compact plant) are known,
information on the effects of severe shoot pruning on root
growth are limited.
Uniform liners of Ilex crenata Compacta in 2-inch pots
were transplanted to PVC containers 6 inches in diameter x
12 inches deep with a window cut from one side 4 inches
across and 8 inches tall. The window was covered with clear
acetate which lined the containers so that roots could be ob-
served periodically.
On September 28, 1983, when the plants were potted,
three treatments were initiated: no pruning, severe pruning
(50 percent of growth removed), and tip pruning (1-2 inches
of terminal shoots removed). One and 2 months later, root and
shoot numbers were counted. At the second sample date, dry
weight was taken on new shoots and total shoots, and fresh
root weight was measured. Weekly data were taken on cu-
mulative root and shoot length by marking three roots and
three shoots per plant and measuring the length.
Shoot pruning at potting reduced root growth 1 and 2
months after potting. Nonpruned plants had 93 and 40 per-
cent greater root numbers I month after potting than severely
pruned and tip pruned plants, table 13. Two months after pot-
ting, tip pruning did not reduce the number of roots or fresh
root weight. However, removal of terminal tips did reduce
cumulative root growth throughout the study, table 14. Non-
pruned plants had 60 and 88 percent greater cumulative root
length than tipped and severely pruned plants, 6 weeks after
[18]
TABLE 13. EFFECTS OF PRUNING ON GROWTH OF JAPANESE HOLLY 1 AND 2 MONTHS AFTER PRUNING'
October 28, 1983 November 28, 1983 Dry weight
Treatment Roots New shoots Roots New shoots New Total new roots
No. No. No. No. Grams Grams Grams
Nonpruned ...................... 14.3a 17.6c 23.5a 25.Ob 3.2a 11.6a 8.1a
Severely pruned .................. 1.0b 41.2a 8.8b 41.2a 4.0a 8.7b 3.8b
Tip pruned ....................... 8.6ab 28.6b 21.1a 32.2b 3.6a 11.3a 5.8ab
Control vs. pruned
2 
............... * ** * ** ns * **
Severely pruned vs. tip pruned2 ..... * ** * s ** *
'Plants were pruned at potting on September 28, 1983.
2Nonsignificant (ns) or significant 
at 5 percent (*) or 1 percent (**) 
level.
TABLE 14. EFFECTS OF PRUNING ON SHOOT AND ROOT GROWTH OF JAPANESE HOLLY'
TreatmentCumulative root length 
Cumulative shoot length
11-10-83 11-17-83 11-24-83 11-10-83 11-17-83 11-24-83
In. In. In. In. In. In.
Nonpruned ............................... 8.0a 11.1a 15.2a 13.6a 17.7a 23.7a
Severely pruned ........................... .9c 1.9c 6.2b 5.6b 5.8b 5.9c
Tip pruned................................. 3.1b 4.9b 8.0b 12.5a 14.9a 17.6b
Control vs. pruning
2 . . . . . . . . . . . . . . . . . . . . .
...
Severely pruned vs. tip pruned2 .............. * * ns ** 
** **
'Plants were pruned at potting on September 28, 1983.
2Nonsignificant (ns) or significant at 5 percent (*) or 1 percent (**) 
level.
potting. Initially, tip pruned plants had greater root length
than severely pruned plants; however, by November 24 root
length was similar between severely pruned and tip pruned
plants. Nonpruned plants had greater root length than
pruned plants, 2 months after potting. Shoot pruning also af-
fected shoot growth. Shoot numbers were increased by se-
vere shoot pruning, table 13. Tip pruning resulted in
increased shoot numbers compared to nonpruned plants. Cu-
mulative shoot length was also affected by pruning in that
nonpruned and tip pruned plants generally had greater shoot
length than severely pruned plants, table 14. However, when
dry weight of new shoot growth was measured 2 months after
potting, growth was similar among treatments, table 13.
These data show that shoot pruning increases shoot num-
bers and results in suppressed cumulative shoot length, pro-
ducing the desired effect of a compact plant. However, when
plants are pruned at potting during the summer months, root
growth is suppressed during the first 2 months. Further-
more, severely pruned plants tend to have a growth flush dur-
ing which new shoots emerge simultaneously, as evidenced by
41.2 new shoots I month after pruning and no additional new
shoots 2 months after pruning, table 13. Consequently, sup-
pressed root growth coupled with a vigorous growth flush
during a time of the year when environmental conditions are
conducive to water stress may adversely affect plant devel-
opment. These data suggest that shoot pruning be omitted at
potting in commercial production or at planting by homeown-
ers. This delay will allow roots to become established before
pruning which will initiate a vigorous growth flush. The data
also indicate that a light tip pruning would have less impact
on root establishment than severe pruning.
See color plate number 5.
Effects of Container Dimension and
Volume on Growth of Three Woody
Ornamentals
Gary J. Keever and Gary S. Cobb
Distribution of roots in the soil is determined by both ge-
netic and environmental factors; however, due to restrictive
container walls, limited growth medium, and high water-
holding capacity of the media, root growth in containers dif-
fers from the field. Studies of seedling trees have shown a sig-
nificant influence of container volume and shape on plant
growth, with larger containers and those with a relatively low
diameter/depth ratio generally producing larger seedlings.
Numerous woody ornamental species are grown in nursery
containers with a typical diameter/depth ratio of approxi-
mately 1:1. Matching the container dimensions to the natural
shape of the root distribution may contribute to stimulating
both canopy and root growth. This study was initiated to in-
vestigate the influence of container width, depth, and volume
on root and shoot growth of three woody ornamentals having
different root growth characteristics. Plants included Rho-
dodendron x Hershey's Red (fibrous and shallow root system),
Ilex cornuta Burfordii Nana (coarse with both lateral and
deep roots), and Euonymus japonica Microphylla (medium
fine and extensive root system).
Uniform liners of each species were potted May 31, 1983,
in an amended peat-perlite (1:1, volume basis) growth me-
dium. Containers were made from white PVC pipe in all
combinations of three diameters, 4, 6, and 8 inches and three
depths, 3, 6, and 12 inches. Plants were placed on raised,
[19]
w
a
.-
a.
0
I-
AO
c'Q
t0
o10.2
FIG. 5. Top dry weight for Burford holly grown in pots of three diam-
eters and three depths (diameter x depth sign).
I6.9
Top dry 
weightg
75
70
65
60
55
50- 
15.2 
c
45-
40-
35
2 5
20 DV
15 ". , ,
Top dry weight,g
75
70
65
60
55
50
45
40
35
30
25
20
15
0 I.
.- -
8
S
0
-1
a0
-$
"
"
20.3cm
$ .*-
TnUS, as gre
15.2 { cm
- (10.2cm 3
- DWDI
= 
39.17+ .22DE
, i, , I , i I i I I A
10 II 12 13 14 15 16 17 18 19 20 21
Pot diameter, cm
7 9 11 13 15 17 19 21 2325 27 29 31
Pot depth,cm
FIG. 6. Top dry weight for euonymus grown in pots of three depths as influenced by pot diameter and grown in pots of three diameters as influ-
enced by pot depth. Equations are for the common regression.
[20]
wire benches in a double polyethylene greenhouse and ele-
vated to an equal pot height. Root and shoot growth were de-
termined in January 1984.
Top dry weight of Burford holly increased as both pot di-
ameter and depth were increased, figure 5. The greatest re-
sponse to pot diameter occurred at the shallower depths and
to pot depth at the smaller diameters. In the wider or deeper
pots, increasing pot depth or diameter, respectively, had
minimal influence on top dry weight. Relative root density of
holly increased as pot depth increased except for a tapering
off of root density in the wider and deeper pots. Roots
reached the bottoms of pots of all depths. Root density was
highest in the lower half of containers, reflecting the rela-
tively deep rooting habit of Burford holly.
Top dry weight of euonymus increased linearly in response
to both increased pot diameter and pot depth, figure 6, with
a greater response from increased diameter. Relative root
density of euonymus was greatest in the narrow, shallow pots
and decreased as pot depth and diameter increased.
Top dry weight of azalea increased linearly in response to
increased pot diameter while pot depth had no effect on dry
weight, figure 7. Relative root density of azalea, like euony-
mus, was greatest in the narrow, shallow pot and decreased
as pot depth increased. This root growth pattern contrasts
with that observed with Burford holly and reflects the shal-
\ \ r r-r r
Top dry 
weight, 
g
37. 5
35.0-
32.5
30.0-
27.5
25.0*
22.5
20.0
17. 5
15.0
12.5 DWDE
= 
4.55 + 1.12DI
10.0
10 II 12 13 14 15 16 7 18 19 2021
Pot diameter, cm
FIG. 7. Top dry weight for azalea grown in pots of three depths as in-
fluenced by pot diameter.
low, natural root distribution of azalea. Root density also de-
creased as pot diameter increased although the response was
less rapid than to pot depth. Roots of azalea did not reach bot-
toms of all pots. Although additional volume of growth me-
dium in wider and deeper pots must be considered a major
contributor to plant response, these results suggest it is ben-
eficial to grow shallow-rooted species in shallow, broad con-
tainers and deep-rooted species in pots deeper than standard
nursery pots.
See color plates numbers 6 and 7.
Woody Plants for Interior Environments
Gary J. Keever and Gary S. Cobb
Most plants used in interior environments are tropical or
semi-tropical in nature, adapting well to conditions of rela-
tively low light, warm temperatures, and low humidity. Many
temperate zone woody plants prefer or will tolerate low light
conditions in the exterior landscape and may provide an ad-
ditional source of plant material for the interior environment
if properly acclimatized. The purpose of this study was to
evaluate for interior use selected temperate woody ornamen-
tals, grown under three production light levels.
Thirty uniform 3-inch liners each of Fatsia japonica (fat-
sia), Gardeniajasminoides Radicans (dwarf gardenia), Pittos-
porum tobira Variegata (variegated pittosporum),
Podocarpus macrophyllus Maki (Japanese yew), Ternstroe-
mia gymnanthera (cleyera);,and Trachelospermum asiaticum
(Asiatic jasmine) were potted July 22, 1983, in amended
milled pine bark-sandy loam (10:1, volume basis) in 6-inch
pots. Plants were divided into three groups of 10 single-plant
replicates of each species and grown outdoors under the fol-
lowing light intensities: (1) full sun; (2) 47 percent shade; and
(3) 64 percent shade. On October 23, plants were transferred
to an interior environment (11.2 uEsec -m
-2 , 
70'F + 20, 80
percent relative humidity) and, over the following 3 months,
were evaluated periodically for sustained quality and growth.
Plant size (growth index = height + width + width + 3)
and leaf size (leaf index = length + width + 2) of fatsia, gar-
denia, and pittosporum were greater for plants grown in
shade compared with those grown in full sun at the end of
both the production cycle and the 
interior evaluation period,
table 15. There was no difference in plant or leaf size of Jap-
anese yew or Asiatic jasmine, regardless of production light
intensity. With cleyera produced in 64 percent shade, plant
size was larger at the end of the interior period compared
with those produced in full sun. Leaf drop, an important cri-
terion for interior plant selection, was least with shade-grown
pittosporum, gardenia, and Asiatic jasmine produced in 64
percent shade. With other species, leaf drop did not vary
with production light levels. At 
the end of the interior period,
plant quality was greatest for shade-grown 
fatsia, gardenia,
pittosporum, and Asiatic jasmine. Cleyera grown in 64 per-
cent shade were superior to those produced in 47 percent
shade or full sun. However, with Japanese yew, production
light levels did not affect plant quality. Foliar color was best
for shade-grown gardenia, pittosporum, and Asiatic jasmine,
but was similar for other species at all production light in-
tensities.
Following the final data collection in January 1984, plants
were maintained in the interior environment until June.
Plants were fertilized every 8 weeks with 100 p.p.m. nitro-
gen from 20-20-20 soluble fertilizer. All plants initiated new
growth during this 5-month period.
The increased use of interior landscapes has created a mar-
ket with the need and potential for new crop selections. With
the exception of fatsia, the other species evaluated in this
study have received limited or no consideration as potential
interior plants. All species evaluated, with the possible ex-
ception of Asiatic jasmine, responded well when placed in the
interior environment. Shade production generally resulted in
highest plant quality.
See color plates numbers 8 and 9.
[21]
TABLE 15. RESPONSE OF SIX WOODY ORNAMENTALS, GROWN AT THREE LIGHT LEVELS, TO AN INTERIOR ENVIRONMENT
Cultivar and production Growth index' Leaf Leaf Quality Color
light level Post-production Post-interior index2 drop
3  
rating
4  
rating5
cm cm
Fatsia
Full sun .................... 12.7b6 15.9c 12.4b 0.7 1.7b 3.8
47% shade .................. 28.6a 32.1b 22.8a .0 4.2a 3.2
64% shade .................. 31.4a 36.6a 24.8a .3ns 4.1a 3.2ns
Dwarf gardenia
Full sun .................... 22.3b 22.6b 3.lb 77.3a 1.5c 1.5b
47% shade .................. 28.0a 28.5a 3.4ab 38.8b 4.1a 3.7a
64% shade .................. 28.6a 28.6a 3.7a 43.8b 3.6b 3.9a
Variegated pittosporum
Full sun .................... 17.4b 17. Ob 3.3b 9.5a 1.5b 1.5b
47% shade .................. 22.2a 22.6a 4.6a 3.3b 3.5a 3.6a
64% shade .................. 23.7a 24.6a 4.8a 2.7b 3.3a 3.8a
Japanese yew
Full sun ...................... 25.9 26.1 5.8 11.3 3.5 5.0
47% shade .................. 27.5 27.2 6.0 7.5 3.6 5.0
64% shade .................. 30.0ns 28.3ns 6.0ns 11.8ns 3.3ns 5.0
Cleyera
Full sun .................... 16.0 15.7b 3.5 6.0 1.3b 2.7
47% shade .................. 16.2 18.2ab 3.9 6.0 1.6b 3.8
64% shade .................. 17. Ins 19.0a 3.8ns 7.5ns 2.4a 3.9ns
Asiatic jasmine
Full sun .................... . 18.9 18.7 2.3b 54.8a 1.4b 1.7b
47% shade .................. 18.9 19.5 2.6a 48.0a 2.9a 4.8a
64% shade .................. 21.3ns 17.4ns 2.7a 33.0b 2.8a 4.7a
'Growth index: (height + width + width) + 3.
2
Leaf index: (leaf length + width) + 
2.
3
Leaf drop: total number of leaves dropped October 1983 to 
January 1984.
4Quality rating: 1 = poor, not salable; 3 = good, salable; 5 = excellent quality.
5Color rating: 1 = light green; 3 = medium green; 5 = dark green.
6Mean separation within columns and species by Duncan's multiple range test, 5 percent level; values followed by the same letter are not statistically
different. ns = no statistical difference among treatments.
Promising Trees for the Southeast
Donna C. Fare, Charles H. Gilliam, Harry G. Ponder,
Wallace A. Griffey, and Hoyt E. Burgess
The need for a comprehensive evaluation of traditional and
new introductions of shade and ornamental trees has long
been recognized by horticulturists, nurserymen, and land-
scape designers. Although most introductions are evaluated
by the producer or in arboretums, little effort has been made
in the Southeast to develop a comparative evaluation in a sin-
gle location. Increased emphasis on tree plantings in cities,
residential districts, and along streets and highways has ac-
celerated the selection and introduction of new species and
cultivars for use in these landscape areas. Limited data have
led to the selection of some trees that are poorly suited to
many sites, resulting in high maintenance and removal costs.
A project to evaluate the characteristics and adaptability of
species and cultivars of shade and ornamental trees is in its
fourth year, and has about 225 species or cultivars of trees.
Trees are being evaluated on their growth rate, fruiting and
flowering characteristics, and adaptability to the Southeast.
Trees were first planted in December 1980, as 1-year-old
plants at the Piedmont Substation, Camp Hill, Alabama. This
report presents information on promising cultivars of two of
the Southeast's most common species, flowering dogwood
and crapemyrtle. Each year additional selections have been
added to the test.
Cornus florida, a native dogwood of the Eastern United
States, has been planted extensively as an understory tree in
many landscapes. It is used as both a specimen tree and in
groupings. Flowering dogwood has a four season landscape
value. In spring it is the white flowers (bracts); during sum-
mer and fall the leaf and fruit color; and in winter the sym-
podial branching habit and bark. True flowers are greenish
yellow and unimportant as a landscape feature. The showy
parts of the inflorescence are the bracts, which are obovate
or emarginate and appear from April to May.
Many cultivars of C. florida are available in the nursery
trade that have white, pink, or red flowers. Only those in-
cluded in the test planting are described. Barton White
blooms when young, and has large white bracts. During the
fourth growing season of our study, there was some sporadic
blooming of Barton White, followed by profuse blooming
during early April of the fifth year. Bay Beauty, a double
white-flowering cultivar, has bloomed prolifically during the
third, fourth, and fifth growing seasons, usually peaking dur-
ing early April. Cloud Nine has bloomed only sporadically
during mid-April in the fourth and fifth years. Cherokee
[22]
L. fouriei
L. fauriei x L. indica
Natchez
L. indico
Byer's Wonderful White
Christmas Time
Weeping White
L. fouriei x L. indico
Muskogee
L. indico
Catawba
Hardy Lavender
New Orleans
Twilight
Byer's Red
Firebird
Mission
Regal Red
Wm. Toovey
Byer's Pink
Pink 18
Potomac
Tulsa
L. fouriei x L. indico
Tuscarora
E M L E M L E M L E M L
June July August September
FIG. 8. Flowering duration of Lagerstroemia species and cultivars.
Princess, known to be a heavy bloomer with large white
bracts, is in its fifth growing season and has not flowered.
First Lady, a white-flowering dogwood with variegated
leaves of yellow and green, has also not flowered during 5
years in the study. Springtime bloomed during early April of
the fifth growing season, producing large white bracts up to
4 inches in diameter.
Cherokee Chief, Pink, Purple Glory, Reddy Red, Rubra,
Sweetwater Red, and Welsh's Jr. Miss are the red-flowering
dogwoods in the study. Welsh's Jr. Miss and Reddy Red had
a few sporadic blooms during April of the fourth year. During
the fifth growing season, all of the red-flowering cultivars
bloomed, but only sporadically.
Bay Beauty, Springtime, and Welsh's Jr. Miss are the fast-
est growing dogwoods, averaging about 20 inches in height
each year. Cloud Nine and First Lady are averaging only a 10-
inch increase in height annually and all other cultivars are av-
eraging 15 inches.
Another interesting native Cornus species is C. stoloni-
fera, commonly known as American dogwood. This species
has been trained into a single trunk tree in this study and has
bloomed profusely from mid-May to mid-June the third,
fourth, and fifth years. Other prominent features are blue
fruit, early fall leaf color, and reddish brown twigs that are no-
ticeable during winter months. American dogwood is aver-
aging 20 inches a year in height growth.
C. kousa, Korean dogwood, is one of the few trees in bloom
during June, usually 3 weeks after C. florida. Bracts are
white, tapered at the end, and can last up to 6 weeks. Only a
few sporadic blooms occurred during the fourth growing sea-
son, but blooms were prolific during the fifth year. With age,
the bark is exfoliating, leaving mottled colors of grey, tan, and
brown. The Korean dogwood is averaging 15 inches a year in
height growth.
In summary, the white-flowering dogwoods have bloomed
more prolifically than the red-flowering cultivars. The Amer-
ican dogwood and C. florida Bay Beauty have bloomed pro-
lifically as young trees and have had the fastest growth among
the dogwoods tested.
Lagerstroemia indica, crapemyrtle, has been commonly
classed as a deciduous shrub, but may also be developed into
a single or multi-trunk tree reaching up to 30 feet in height.
[23]
Crapemyrtles are used as accent trees in formal or informal
gardens, and in street and highway plantings. L. fauriei, an-
other cultivated crapemyrtle, has similar landscape poten-
tial.
Both species have year-round landscape attractions. In
summer, flowers range from red to white to lavender in color.
Until recently, most crapemyrtles were sold only by flower
color-red, pink, white, 
or lavender. Within the last 
decade,
named cultivars have resulted from breeding programs. Se-
lections of white-flowering crapemyrtles in the test are L.
fauriei x L. indica Natchez, L. indica Byers Wonderful
White, Christmas Time, and Weeping White. L. fauriei has
a long flowering period, from late June to early September,
figure 8, and is scented with a light lemon fragrance.
Natchez, the earliest to bloom of the white-flowering culti-
vars, has thick tapered panicles of flowers while Byer's Won-
derful White has long panicles, up to 11 inches, with sparse
flowers. Christmas Time is last to bloom, has short panicles,
up to 4 inches, but has the purest white corolla of the white
cultivars. Christmas Time also has distinctive light green fo-
liage.
L. fauriei x L. indica Muskogee, and L. indica Catawba,
Hardy Lavender, New Orleans, Powhatan, and Twilight have
lavender flowers. Muskogee, the longest-flowering lavender
crapemyrtle, has tapered rose panicles. Catawba, New Or-
leans, Powhatan, and Twilight are similar in color and dura-
tion. New Orleans has darker green foliage than the other
lavender crapemyrtles. Hardy Lavender has a light lavender
flower and blooms about 1 week longer than the other laven-
der crapemyrtles.
Byer's Red, Firebird, Mission, Regal Red, and Wm.
Toovey are red-flowering crapemyrtles. Of the red crape-
myrtles, Regal Red has the shortest flowering period. Mis-
sion, a late-flowering crapemyrtle, begins flowering in late
July and continues through mid-September. It has flower
panicles similar in size to Regal Red, but not as full. Firebird
has an upright growth habit and the flowers hold their red
color well throughout the summer.
Pink selections being evaluated are Byer's Pink, Pink 18,
Potomac, Tulsa, and Tuscarora. Tuscarora, the longest-bloom-
ing pink crapemyrtle, has a full flower panicle when in
bloom. Individual flowers in the panicle open about the same
time which gives a heavy bloom effect. Byer's Pink, Pink 18,
Potomac, and Tulsa have shorter flower panicles, 3-5 inches
long, and have not bloomed prolifically in the study.
Average flower size of each selection was calculated each
summer. Measurements from five flowers from each plant
were used to determine the average size flower panicle, table
16. By 1984, all selections but Powhatan have had four grow-
ing seasons in the test (Powhatan has had only three). L. fau-
riei has had the largest overall flower panicle, but as the
selections mature each year, the flower sizes are also increas-
ing. This trend will probably taper off and flower size will be-
come more consistent as the crapemyrtles reach mature size.
Bark characteristics are an added landscape feature of
crapemyrtles in winter and spring. Trunks and branches have
thin smooth bark which peels in long shreds to reveal a tan
mottled bark. L. fauriei, Muskogee, and Natchez have dem-
onstrated this trait after 3 years in the test plot.
L. fauriei, Muskogee, and Natchez had the greatest height
and caliper growth rate, table 17. While there are significant
TABLE 16. AVERAGE FLOWER SIZE OF CRAPEMYRTLE SELECTIONS
Plant 
Flower 
size'
1982 1983 1984
cm cm cm
Byer's Red ................. 185.9bcd2 212.7cd 258.Oij
Byer's Wonderful White..... 570.5a 572.6a 725.6b
Catawba ................... 78.7d 199.8cd 276.2hij
Firebird ................... 212.2bc 315.2bc 366.9efgh
Hardy Lavender ............ 279.7b 344.7b 493.5cd
L. fauriei ................... 285.3b 563.1a 1112.8a
Mission.................... 259.4bc 276.0bcd 329.4fghij
Muskogee.................. 142.42cd 241.2bcd 537.6c
Natchez ................... 203.2bcd 303.8bc 400.0Odefg
Powhatan .................. 168.7d 258.0ij
Regal Red.................. 280.3b 270.1bcd 321.0ghij
Tuscarora .................. 195.3bcd 206. cd 337.6efghi
Wm. Toovey ............... 239.4bc 300.9bc 430.9def
'Flower size determined by length x width of the flower panicle.
2
Mean separation within columns by Duncan's multiple range test, 5 per-
cent level; values followed by the same letter are not statistically different.
differences in growth rate among the cultivars, the pink-flow-
ering crapemyrtles are showing a trend to be less vigorous
growers and less cold hardy than other cultivars. In April
1983, a late frost caused winter damage to many of the crape-
myrtles. The leaves were beginning to unfurl when the frost
occurred and the pink-flowering crapemyrtles, excluding
Tuscarora, were damaged the most.
During the winter of 1983-84 the Southeast had an unu-
sually cold winter with temperatures near zero for several
days. Winter damage was assessed on the crapemyrtles the
following spring.
Pink-flowering crapemyrtles were the least cold hardy, suf-
fering branch dieback to the soil line or death. Tuscarora and
Potomac were exceptions, having little or no damage. Byer's
Wonderful White and L. fauriei had no winter damage, but
other white-flowering selections had some stem dieback.
Hardy Lavender and Powhatan escaped winter damage but
other lavender-flowered crapemyrtles had some dieback.
New Orleans had severe dieback to the soil level but pro-
duced new shoots during the growing season. Overall, the
red-flowering crapemyrtles were the most cold hardy, with
only Byer's Red suffering stem dieback.
Powdery mildew is the most serious disease of crape-
myrtle, especially in the spring and fall months. Many of our
cultivars are resistant or tolerant to the disease. Wmin. Toovey
is the only cultivar that has had a mildew problem on the fo-
liage, while Firebird has had some powdery mildew on the
flower panicles. This occurred in late summer and fall of 1982
and 1983.
In conclusion, the data suggest the more recently devel-
oped crapemyrtle cultivars, Muskogee, Natchez, Hardy Lav-
ender and L. fauriei, are showing trends of more vigorous
growth in respect to height and caliper, while L. fauriei,
Muskogee, Natchez, Tuscarora, and Hardy Lavender have the
greatest duration of flowering. Recent crapemyrtle selec-
tions, such as Natchez, Muskogee, L. fauriei, and Byer's
Wonderful White, have the largest flower panicles.
See color plates numbers 10-13.
[24]
TABLE 17. HEIGHT AND CALIPER GROWTH FOR LAGEISTROEMJA SPECIES AND CULTIVARS
Plant 
Height 
Caliper
1981 1982 1983 1982 1983
cm cm cm cm cm
L. fauriei.................................. 137.2a' 167.8a 222.1a 2.6a 4.Oa
L. faurici x L. indica
Natchez................................. 101.7b 157.8ab 201.6ahc 2.2abc 3.5ab
L. irdica
Byer's Wonderful White................... 69. 3cd 121.7cdef 132.Sefg 1.6def 1.9defghi
Christmas Time .......................... 109.Odefg 95.Oghi 1.3ef 1.4ghi
Weeping White........................... 96. lefgh 92.9ghi 1.4ef 1.3hi
L. faurici x L. indica
Muskogee ............................... 89.4bc 144.4ahc 212.Sah 2.3ahc 3.8a
L. indica
Catawba ................................ 72.Oh 89.Gghi 1.2ef 1.Sefghi
Hardy Lavender ............... .......... 62.4cd 125. Ibcde 175.2hcde 2.3ah 3.6ahc
New Orleans............................. 61.lcd 94.Oefgh 78.2i 1.6def 1ii
Twilight ................................. 63.3cd 135.Oahcd iSSOdef 2.7ahcd 3. lahc
Byer's Red................................ 54.4d 92.2efgh 128.9fgh 1.7cde 2.3cdefg
Firehird......................................... 112.4cdefg 157.4cdef 1.6def 2.3cdefg
Mission................................... - 96. lefgh 163.Ocdef 1.4ef 2.6hcdef
Regal Red................................ 59. lcd 103.Sdefgh 158.6cdef 1.6def 2.6hcdef
Win. Toovey.............................. 56.4d llti.2cdef 145.ldef 1.7de 2.7hcde
Byer's Pink............................... 54.3d 95.Sefgh 83.9hi 1.2ef 1.i
Pink 18................................... - 88.7fgh 78.6i 1.4ef 1.3hi
Potomac.................................. - 91.2efgh 89.Oghi 1.4ef 1.ii
Tulsa............................................ 86.7fgh 86.Ohi 1.Of 1.ii
L. fauriei x L. irtdica
Tuscarora........................................ 79.6gh 123. Ofghi 1.2ef 1. 7efghi
'Mean separation within columns hy Duncan's multiple range test, 5 percent level; values followed hy the same letter are not statistically different.
DISEASE AND INSECT CONTROL
Control of Entomosporium Leaf Spot on
Photinia Under Conditions of
High Disease Pressure
Gary S. Cobb, Austin K. Hagan, Charles H. Gilliam,
and Jacqueline M. Mullen
Leaf spot caused by Entomosporium maculatum is a per-
sistent and destructive disease of Photinia and some other Ro-
seaceae genera. Since splashing water and high humidity are
conducive to disease development, this leaf spot is particu-
larly damaging and difficult to control during periods of fre-
quent rainfall and in nurseries equipped with overhead
irrigation. Benlate and Daconil 2787 have been reported to
be effective protectants against F. maculatum, but in com-
mercial nurseries the results with these materials are often
less than satisfactory, particularly when disease pressure is
high. Ini fact, disease severity and the lack of effective control
measures have resulted in some nurseries ceasing photinia
production. The objectives of this work were to identify non-
phytotoxic fungicides that would provide an acceptable level
of preventative disease control under conditions of high dis-
ease pressure and to establish the appropriate rates and fre-
quencies of application.
In spring 1983, several fungicides were screened for phy-
totoxicity and protectant efficacy in controlling Entomospor-
mum leaf spot on P. xfraseri (Fraser photinia or red tip). The
most effective material was further studied to determine ap-
propriate application practices. A second fungicide compari-
son was made in fall 1983, with follow-up studies in spring
1984. All experiments were conducted using severely pruned
photinias grown in an amended pine bark medium in 3-gallon
pots. Treatments were initiated when new foliage began to
expand. E. maculatum inoculum was provided by placing se-
verely diseased photinias on the container rims of the test
plants. With daily overhead irrigation, severe disease symp-
toms consistently developed on control plants within 4 weeks.-
Fungicides were sprayed on all leaf surfaces until runoff and
plants were not irrigated for 24 hours after application. An ad-
juvant, Chevron Spray Sticker (8 ounces per 100 gallons of
water), was included with all treatments unless otherwise
noted. Disease levels on new foliage and phytotoxicity were
assessed 4 weeks after treatment initiation.
In the initial screening test in spring 1983, Triforine
18.2%EC, Bayleton 25WP, Daconil 2787 75WP, Ornalin
5OWP, Benlate 5OWP, and Manzate 200 8OWP were com-
pared. Fungicide applications were made weekly
Three separate experiments with Triforine were conducted
simultaneously in summer 1983. In one experiment, Triforine
at 0. 5, 1.0, 1.5, and 2. 0 pints per 100 gallons of water was ap-
plied weekly for 4 weeks. In a second experiment, Triforine
at 2 pints per 100 gallons of water was applied at 7, 14, 21, and
28-day spray intervals. Effects of weekly application of Tni-
forine (2 pints per 100 gallons of water) with and without the
[25]
spray sticker was investigated in a third experiment. Over-
head irrigation was applied 24 hours after treatment and at
24-hour intervals thereafter.
Weekly applications of Triforine, Bayleton, Tilt 3.6EC,
Zyban 75WP, Rovral 50WP, and Kocide 77WP were evalu-
ated in fall 1983. In spring 1984, Zyban was applied weekly
at 0, 0.5, 1.0, and 1.5 pounds per 100 gallons of water and at
1.5 pounds per 100 gallons of water at 7, 14, and 21-day spray
intervals. To investigate phytotoxicity, uninfected photinias
were pruned and subjected to 4 weekly applications of Bay-
leton at 1 pound per 100 gallons of water. New shoot growth
was compared with an untreated control.
TABLE 18. COMPARISON OF SIX FUNGICIDES AS PROTECTANTS AGAINST
ENTOMOSPORIUM LEAF SPOT ON PHOTINIA, SPRING 1983
Rate per 
Percent
Fungicide 100 gal. water infected
Triforine 18.2%EC (triforine) ....... 1.0 qt. la'
Bayleton 25WP (triadimefon) ........ 1.0 lb. 5a
Daconil 2787 75WP (chlorothalonil) . 1.5 lb. 18b
Ornalin 50WP (vinclozolin) ......... 1.5 lb. 22b
Benlate 50WP (benomyl) ........... . 1.0 lb. 53c
Manzate 200 80WP (mancozeb) 1.5 lb. 61c
Check ........................... 95d
'Mean separation within columns by Duncan's multiple range test, 5 per-
cent level; values followed by the same letter are not statistically different.
In spring 1983, all fungicides reduced incidence of Ento-
mosporium leaf spot compared with the control; however, ef-
ficacy varied among materials, table 18. Greatest disease
control was observed with weekly applications of either Tri-
forine or Bayleton. No phytotoxicity wasobserved with Tri-
forine, but leaves of Bayleton-treated plants were narrower
and more bronze in color, and plant height was reduced com-
pared with the check. Leaf spot was substantially reduced by
Daconil 2787 and Ornalin, and no phytotoxicity was observed
with either fungicide. While Benlate and Manzate 200 re-
duced leaf spot incidence, disease developed on more than 50
percent of the leaves. High disease pressure in the test was
reflected by the 95 percent leaf spot incidence on control
plants.
Good disease control was achieved with all rates of Trifor-
ine tested; maximum control was obtained with 2 pints per
100 gallons of water (data not shown). When Triforine at 2
pints per 100 gallons of water was applied at intervals exceed-
ing 1 week, disease control declined dramatically (data not
shown). At a 2-week interval, 55 percent of the new leaves
were infected and disease severity increased significantly;
disease severity increased linearly as application interval in-
creased. Weekly applications of Triforine at 2 pints per 100
gallons of water resulted in 98 percent uninfected leaves with
or without the spray sticker included.
In fall 1983, Triforine, Tilt, and Zyban provided excellent
control of leaf spot, table 19; however, Tilt caused reddening,
spotting, and some distortion of expanding foliage. Bayleton
was less effective, but no phytotoxicity was observed, possi-
bly due to cooler temperatures during the fall. Disease con-
trol with Rovral and Kocide 101 was only slightly better than
the control. Disease control increased as the rate of Zyban in-
creased; greatest control was obtained at 1.5 pounds per 100
TABLE 19. COMPARISON OF Six FUNGICIDES AS PROTECTANTS AGAINST
ENTOMOSPORIUM LEAF SPOT ON PHOTINIA, FALL 1983
Fungicide 
Rate per 
Disease'
Fungicide 100 gal. 
water Incidence Severity
Triforine 18.2%EC
(triforine) ...... ............ 1.0 pt. 2a
2  
1.Oa
Tilt 3.6EC (propiconazole) .... .5 pt. a 1a
Zyban 50WP (thiophanate-
methyl + zinc ion
+ maneb) ............... 1.5 lb. 5a 1.2a
Bayleton 25WP (triadimefon).. 1.0 lb. 19b 1.8b
Rovral 50WP (iprodione) ..... 1.0 lb. 80c 3.3c
Kocide 101 77WP (copper
hydroxide) ................. 1.5 lb. 85c 3.5c
Check ..................... - 100d 4.0d
'Average disease incidence determined by percent new leaves infected.
Average disease severity: 1 = no symptoms, 3 = moderate infection, and
5 = defoliation.
2
Mean separation within columns by Duncan's multiple range test, 5
percent level; values followed by the same letter are not statistically
different.
gallons of water (data not shown). Weekly application of
Zyban provided the greatest disease protection; however,
control decreased linearly as spray interval increased (data
not shown). In spring 1984, four weekly applications of Bay-
leton (1 pound per 100 gallons of water) reduced dry weight
of new shoot growth 43 percent compared with the check.
Results using fungicides for control of Entomosporium leaf
spot have often conflicted, possibly because of differences in
disease pressures and cultural and environmental variations.
Although time of year varied, the results reported here were
obtained under similar experimental conditions of consist-
ently heavy disease pressure. Weekly applications of Trifor-
ine at 1-2 pints per 100 gallons of water gave near-complete
disease control, and subsequent trials in commercial nurser-
ies have substantiated these results. Under conditions less fa-
vorable to disease development, fewer applications and/or
lower rates of Triforine may be sufficient. Zyban at 1.5 pounds
per 100 gallons of water applied weekly provided excellent
disease protection without phytotoxicity. Daconil 2787 and
Ornalin offer substantial disease protection and could prove
effective under conditions less favorable for disease develop-
ment or in fungicide rotations.
See color plate number 14.
Control of Anthracnose on Euonymus
Gary S. Cobb
Euonymus japonica cultivars are reported to be suscep-
tible to several foliar diseases. A leaf spot caused by Colle-
totrichum gloeosporioides was identified on E. japonica
Aureo-marginata (Golden euonymus) in Mobile County,
Alabama, in summer 1983. Small circular lesions, 1-3 milli-
meters in diameter, were found on both leaf surfaces and on
stems. Foliar lesions, which often exhibited a scab-like ap-
pearance, had raised, purplish-brown margins and sunken,
[26]
TABLE 20. COMPARISON OF 11 FUNGICIDES AS PROTECTANTS AGAINST COLLETOTRICHUM LEAF SPOT ON GOLDEN EUONYMUS
Rate per Percent Disease
Fungicide 100 gal. water 
infected rating
Zyban 75WP (thiophanate-methyl + mancozeb) .............................. 1.5 lb. la
2  
1.0a
2
Daconil2787 75WP (chlorothalonil) ........................................ 1.0 lb. 2a 1.2a
Benlate 50W P (benom yl) .................................................. 1.0 lb. 4a 1.2a
Manzate 200 80WP (mancozeb) ............................................ 1.5 lb. 4a 1.5a
Kocide 101 77W P (copper hydroxide) ....................................... 1.5 lb. 40b 3.0b
Tilt 3.6EC (propiconazol) ................................................ 5 pt. 46bc 3.2b
Rovral50W P (iprodione) .................................................. 1.01 lb. 57bc 3.7c
Ro 15-1297
3  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
76 m l 61bcd 3.8c
Ornalin 50W P (vinclozolin) ................................................ 1.0 lb. 65bcd 3.8c
Triforine 18.2% EC (triforine) ............................................... 2.0 pt. 70cd 3.8c
Bayleton 25W P (triadim efon) ............................................... 1.0 lb. 85d 4.0c
C ontrol ................................................................. 57b c 4.0c
'Disease rating scale: 1 = clean; 2 = slight infection; 3 = moderate infection (marketing affected); 4 = heavy infection; 5 = severe infection with
defoliation.
2
Mean separation within columns by Duncan's multiple range test, 5 percent level; values followed by the same letter are not statistically different.
3
MAAG Agrochemicals, Vero Beach, Florida 
32960.
lighter brown centers. Leaf spots coalesced to form large, ir-
regularly shaped lesions where acervuli (fruiting bodies) de-
veloped and were visible to the naked eye as small, pinpoint
black dots. In most cases, stem lesions were entirely raised
and darker in color than foliar lesions.
C. gloeosporioides was isolated on acidified potato-dex-
trose agar medium and confirmed as the causal organism by
satisfying Koch's postulates. Golden euonymus (1-gallon) in
an active flush of growth was treated September 12, 1983,
with the fungicides outlined in table 20. Twenty-four hours
later foliage and stems of plants were sprayed with a conidial
suspension (5 x 104 conidia per milliliter) with a hand-
pumped atomizer until plant surfaces glistened. Plants were
placed in plastic bags for 48 hours. Plants were evaluated for
percent new leaves infected and disease rating ( 1 = no in-
fection, 5 = severe infection and defoliation) on September
26. C. gloeosporioides was isolated from all infected test
plants.
Another cultivar, E. japonica Aureo-variegata (Gold Spot
euonymus), was treated with fungicides and inoculated at
the same time as the Golden euonymus; however, these
plants had only a few actively growing shoots. Observations
on disease incidence, symptoms, and leaf age effects on sus-
ceptibility were made.
Zyban, Daconil 2787, Benlate, and Manzate 200 provided
excellent protection against Colletotrichum leaf spot on eu-
onymus with no phytotoxicity on either cultivar, table 20.
Other fungicides did not protect against disease develop-
ment.
Immature expanding leaves on both cultivars were highly
susceptible to infection; however, mature, fully expanded
leaves were not susceptible, suggesting that fungicidal ap-
plications should coincide with growth flushes. Symptom
expression differed slightly on Gold Spot, with foliar lesions
generally darker and more scab-like (raised) than on Golden
euonymus.
See color plate number 15.
Fungicides for Black Spot Control on Roses
Austin K. Hagan, Charles H. Gilliam, and Donna C. Fare
Black spot, the most widespread and destructive disease
of roses in Alabama, can be controlled with a season-long fun-
gicide spray program. Among the many fungicides currently
available for rose black spot control, Daconil 2787 generally
provides the best results. However, the usefulness of this fun-
gicide is often limited during hot summer months due to fo-
liar burn. Triforine (sold as Funginex) is one of a group of new
experimental fungicides known as sterol-inhibitors. Recently
labelled for control of several diseases of roses, including
black spot, Triforine has proven to be as effective as Daconil
2787 without the danger of foliar burn. Other sterol-inhibit-
ing fungicides may prove equal or superior to Triforine and
other fungicides for black spot control on roses. This research
compared the effectiveness of several experimental sterol-in-
hibiting fungicides with fungicides currently recommended
for control of rose black spot.
Triforine 18.2E, Zyban 75W, Daconil 2787 4.17F, Rubigan
12.5E, Maag RO 15-1297, Ortho XE779 25W, and RH-3866
2E were compared for black spot control on field-grown
Queen Elizabeth roses. Each rose plant was fertilized at
planting in September 1983 and then bimonthly beginning in
1984 with 8 ounces of 8-8-8 fertilizer. Plants were pruned pe-
riodically during the growing season to remove suckers and
spent flowers. Water was applied as needed by overhead ir-
rigation. To ensure heavy disease pressure in 1984, roses
were not sprayed for black spot in the fall of 1983. Each fun-
gicide was applied weekly to runoff with a hand pump, com-
pressed air sprayer to a total of eight roses from March 22 to
August 17, 1984. Disease severity was evaluated on May 29,
June 21, and August 21 on a 1-5 scale: 1 = no disease, 5 =
severe defoliation.
Weekly applications of the different fungicide treatments
failed to prevent black spot development, table 21. However,
all treatments significantly reduced disease severity through
the growing season and several were quite effective against
black spot.
[27]
TABLE 21. COMPARISON OF FUNGICIDES FOR
BLACK SPOT CONTROL ON ROSES
Treatment and ratio Disease severity
1
per 100 gal. Water May 
29 June 21 August 21
Maag RO 15-1279 4E, 1.4 fl. oz......... 1.1d
2  
1.4de 2.1d
Maag RO 15-1279 4E, 2.7 fl. oz ........ 1.ld 1.de 1.4e
Zyban 75W, 14.8 oz .................. 2.0bc 1.6ed 1.8de
Rubigan 12.5E, 6.8 fl. oz. ............ 2.1bc 2.0c 3.1b
Daconil 2787 4.17F, 32 fl. oz...........1. 16bcd 1.0e 1.3e
Triforine 18.2, 12 fl. oz................ 1.6bcd 1.1de 1.3e
Ortho XE779 25W, 1.8 oz..............2.3b 2.5b 3.4b
Ortho XE779 25W, 3.2 oz..............2.3b 2.6b 3.1b
Ortho XE779 25W, 6.4 oz..............2.1bc 2.0c 2.9bc
Ortho XE779 25W, 12.8 oz........... 2.1bc 1.6cd 2.3cd
RH-3866 2E, 0.5 fl. oz.................1.6bcd 1.1de 2.4cd
RH-3866 2E, 1.0 fl. oz................1.3d 1.0e 1.9de
RH-3866 2E, 2.0 fl. oz.................1.5cd 1.0e 1.3e
Untreated control .................... 3.4a 3.9a 4.3a
'Disease rated on a 1-5 scale: 1 = no disease, 5 = severe defoliation.
2
Mean separation within columns by Duncan's multiple range test, 5
percent level; values followed by the same letter are not statistically
different.
As expected, Triforine and Daconil 2787 had good season-
long activity against black spot. Zyban also provided a high
level of control though it was slightly less effective than Da-
conil 2787 or Triforine.
Of the experimental fungicides screened, Maag RO 15-
1297 and RH 3866 provided the best disease control. At all
application rates, both fungicides proved as effective as Da-
conil 2787, Triforine, or Zyban in reducing black spot devel-
opment through June 21. Under heavy mid-season disease
pressure, efficacy of the lowest application rates of Maag RO
15-1297 and RH-3866 began to decrease. By August 21, these
treatments no longer provided adequate disease control.
Both fungicides continued to maintain good black spot control
through August 21 at the higher application rates.
Rubigan and Ortho XE779 significantly reduced disease
severity below levels on the nonsprayed 
controls, table 21;
however, neither of these fungicides provided adequate dis-
ease control when compared to Daconil 2787 or Triforine.
Performance of Ortho XE779 declined as its application rate
was reduced from 12.8 to 3.2 ounces per 100 gallons of water.
All fungicides screened, with the exception of Daconil
2787 and Zyban, belong to a group of fungicides often called
sterol-inhibitors. Some sterol-inhibiting fungicides not only
inhibit the growth of fungi but also can act as plant growth
regulators. Ortho XE779 was the only fungicide which had an
adverse effect on plant growth. Roses sprayed with this fun-
gicide had a distinctly compact growth habit, especially at
higher application rates. In addition, fewer fast-growing
suckers were noted on the Ortho XE779 treated roses. None
of the other fungicides was phytotoxic to roses.
Of the four experimental sterol-inhibiting fungicides
screened, RH-3866 and Maag RO 15-1297 looked most
promising for black spot control on roses. At highest appli-
cation rates, both of these fungicides almost completely pre-
vented disease development over a 5-month period under
heavy disease pressure. Performance of RH-3866 at 2.0 fluid
ounces per 100 gallons of water and Maag RO 15-1297 at 2.7
fluid ounces per 100 gallons of water was equal to or sur-
passed that of the fungicide standards, Daconil 2787, Trifor-
ine, and Zyban. Lower application rates that were not highly
effective in this test could provide good black spot control un-
der light to moderate disease pressure. Rubigan and Ortho
XE779 had some activity against rose black spot; however,
neither of these fungicides proved as effective as Daconil
2787 or Triforine. In addition, strong growth regulator activ-
ity could greatly limit the use of Ortho XE779 on roses and
possibly other woody ornamentals.
See color plates numbers 16 and 17.
Susceptibility of flex Cultivars to Black
Root Rot
Lorie E. Merrill, Kenneth C. Sanderson, and John C. Williams
Black root rot caused by Thielaviopsis basicola Ferrasis is
a soilborne disease and has been reported to occur on Japa-
nese hollies, Ilex crenata Thumb, in Alabama, Florida, North
Carolina, and Tennessee. Above-ground symptoms of the dis-
ease include stunted growth, leaf chlorosis, reduced foliage,
and dieback. Roots become necrotic and turn black. Micro-
scopic examination of Japanese holly roots colonized by T.
basicola show conidia and chlamydospores in and on the root
tissue. Plants slowly decline and die after 3 to 4 years.
To determine the relative susceptibility of seven Ilex cul-
tivars to T. basicola, a controlled growth chamber experiment
was initiated. Hollies tested were I. aquifolium x I. cornuta
Nellie R. Stevens, I. x aquipernyi Brilliant, I. cornuta Bur-
fordii x I. pernyi Lydia Morris, I. cornuta Burfordii Nana, I.
crenata Helleri, I. pernyi Franch, and I. vomitoria Stokes
Dwarf.
Liners, growing in 3- x 3-inch plastic containers, were ob-
tained from a commercial nursery and repotted in 1-gallon
plastic containers. The growth medium consisted of equal
parts of sandy loam soil, Canadian sphagnum peat moss, and
pine bark amended with 0.5 pound of ground dolomitic lime-
stone and 0.18 pound of superphosphate per cubic yard.
Plants were fertilized every 2 weeks with an aqueous solution
of 20-20-20 soluble fertilizer (250 p.p.m. N-P-K). After re-
potting, the plants were grown in a glass greenhouse for 7
weeks prior to being moved to a growth chamber. In the
growth chamber, plants were set on inverted, plastic pots to
reduce chance of contamination from runoff A light intensity
of 2,500 foot-candles was provided by cool white fluorescent
and incandescent lamps. Plants were grown on a 9-hour day-
length at a minimum night temperature of 55oF and a day
temperature of 65?E
Two isolates of T. basicola obtained from I. crenata were
grown on PDA medium for 3 days at 74?E Mycelial disks were
transferred to flasks containing a 10 percent V-8 juice broth
medium and incubated in darkness at 74oF for 14 days. In-
ocula containing spores and mycelia were prepared from the
broth cultures and applied at the rate of 3.3 ounces per pot.
NAfter 4 weeks, root balls were washed and rated on a scale of
1 to 5 (1 indicating a healthy root system and 5 indicating all
roots dead). To establish the presence of Thielaviopsis, soil
[28]
TABLE 22. ROOT RATINGS OF SEVEN ILEX CULTIVARS 4 WEEKS AFTER INOCULATION WITH THIELAVIOPSIS BASICOLA
Root rot rating'
Ilex cultivars I. crenata I. crenata
Noninoculaisolate 1 isolate 2
I. aquifolium x I. cornuta
N ellie R. Stevens ................................................... 1.0a
2  
1.0a 1.0a
I. x aquipernyi Brilliant ................................................ 1.0a 1.6ab 2.0b
I. cornuta Burfordii x I. pernyi Lydia Morris ........................... 1.Oa 1.Oa 1.0a 1.0a 1.0a
I. cornuta Burfordii Nana ............................................... 1.0a 1.0a 1.0a
I. crenata H elleri ...................................................... 1.0a 3.0c 3.4c
I. pernyi ............................................................. 1.0a 3.0c 2.6b
I. vomitoria Stokes Dwarf .............................................. 1.0a 1.8b 2.2b
'Root rot rating system: 1 = all roots healthy, 2 - few roots involved, 3 = moderate root rot, 4 = most roots involved, 5 = all roots dead. Mean of 5
plants.
2
Mean separation within columns by Duncan's multiple range test, 5 percent level; values followed by the same letter are not 
statistically different.
and root samples were taken and cultured on carrot disks in
sterile Petri dishes. Samples were incubated for 7 to 8 days at
room temperature (67
0
F) and then examined microscopically
to determine the colonization and the percent recovery of T.
basicola.
Of the seven Ilex cultivars inoculated, I. crenata Helleri
and I. pernyi had the highest root rot ratings, table 22, but
no apparent symptoms of black root rot were evident on
leaves or stems of any test plants. No root damage was ob-
served on I. aquifolium x I. cornuta Nellie R. Stevens, I. cor-
nuta Burfordii x pernyi Lydia Morris, or I. cornuta Burfordii
Nana. The two isolates of T. basicola showed no significant
difference in pathogenicity (data not shown). Recovery of T.
basicola on carrot disks was possible from all inoculated
plants, even apparently healthy roots (data not shown). T.
basicola was not recovered from noninoculated plants (data
not shown). Results of this investigation revealed cultivar dif-
ferences in susceptibility to black root rot. Further research
is warranted to find additional substitutes for susceptible hol-
lies.
See color plates numbers 18 and 19.
Control of Pseudomonas Leaf Spot on
Magnolia grandiflora
Jacqueline M. Mullen and Gary S. Cobb
In the spring of 1981, a previously unreported leaf spot on
southern magnolia was observed in a nursery in south Ala-
bama. Later the same year, a similar disease was found at two
other locations. Young, newly unfolded leaves were most se-
verely affected, developing dark brown spots which expanded
and coalesced until as much as two-thirds of the leaf area was
covered with dark brown irregular lesions. Many lesions
dried and deteriorated, leaving large holes in the leaf tissue.
Expanding leaves developed black spots (0.1-0.4 inch in di-
ameter) surrounded by thin yellow halos (less than 0.1 inch
wide). Mature current-season foliage typically developed
small black spots (less than 0.1 inch in diameter) surrounded
by thin pale yellow halos (less than 0.1 inch wide). Bacteria
isolated from these spots was subsequently identified as Pseu-
domonas cichorii, and pathogenicity tests confirmed P. ci-
chorii as the causal agent of the southern magnolia leaf spot.
Tests were designed to evaluate various chemical and cul-
tural treatments for prevention of disease spread. Severely
infected southern magnolias were grown in a pine bark me-
dium in 5-gallon containers in full sun. Normal nursery cul-
tural practices were followed with the exception of pesticide
applications and irrigation. Spray treatments were applied
weekly to the foliage until runoff, using hand pump com-
pressed air sprayers. Nu-film 17, an adjuvant, was included
with each bactericide treatment.
Experiment 1. Three bactericides, each at two rates, were
evaluated for disease control. Also, two rates of Exhalt 800, a
sticker-extender, were evaluated to determine if a layer of in-
ert material would provide protective disease control. Treat-
ments and rates are given in table 23. Irrigation was applied
daily with overhead impulse sprinklers. Disease incidence
(percent leaves infected) and severity (foliar-disease rating)
were recorded after 7 weeks of treatment.
TABLE 23. CHEMICAL CONTROL OF PSEUDOMONAS LEAF SPOT ON MAGNOLIA
GRANDIFLORA, EXPERIMENT 1
Treatment and rate per Percent leaves Foliar
100 gallons water' infected 
disease rating
2
Kocide 101 (copper hydroxide)
1 lb. ..................... 66 1.9
2 lb. ..................... 61 1.8
Tri-basic Copper Sulfate
(basic copper sulfate)
2 lb ..................... 56 1.7
4 lb. ..................... 47 1.6
Citcop 4E (copper resinate)
2pt. .................... 74 2.1
4 pt ...................... ? 84 2.5
Exhalt 800
4 pt. ..................... 85 2.4
8 pt ...................... 97 2.7
Check ..................... 97 2.7
'Nu-film 17, 1 pint per 100 gallons, was added to each bactericide treat-
ment.
2Foliar disease rating: 1 = no lesions, 2 = less than 10 percent total leaf
area damaged, and 3 = more than 10 percent total leaf area damaged.
[29]
Disease incidence (percent leaves infected) and disease se-
verity (foliar disease rating) were suppressed by all treat-
ments except Exhalt 800, table 23. According to statistical
test results (analysis of variance with orthogonal compari-
sons), Kocide 101 and Tri-basic Copper Sulfate were most ef-
fective, with Tri-basic Copper Sulfate providing greatest
control. Application rates were not significant with either ma-
terial.
Experiment 2. Four chemicals were evaluated in an ex-
periment where overhead irrigation was compared with
ground-level irrigation for leaf spot disease control. The
chemicals and rates tested per 100 gallons of water were Ko-
cide 101, 2 pounds; Tri-basic Copper Sulfate, 2 pounds; Agri-
Strep 17, 1 pound; and Bordeaux mixture, 8 pounds. Disease
incidence and severity were evaluated after 15 weeks of treat-
ment.
None of the chemicals evaluated (by analysis of variance) in
Experiment 2 provided significant disease control. However,
disease severity on hand-watered plants was lower than that
on plants watered by overhead irrigation.
Results of the two experiments showed that Kocide 101 or
Tri-basic Copper Sulfate will provide limited disease control
under some environmental conditions. When humid, rainy
conditions prevailed, as was the case during much of the du-
ration of Experiment 2, neither of these chemicals provided
effective disease control. Results of Experiment 2 also re-
vealed that water droplets are an important element in dis-
ease spread. Plants watered with ground-level irrigation
developed less disease than plants watered with overhead
sprinklers.
Combining chemical and cultural control methods did not
provide adequate disease control when conditions for disease
development were favorable. As with some other bacterial
diseases of ornamental crops, control of this disease in nur-
series will require strict sanitation practices in addition to
chemical and/or cultural control measures.
See color plates numbers 20 and 21.
Pesticide Phytotoxicity and Residue
Accumulation on Poinsettia
Dean R. Mills, Ronald L. Shumack, and Gary S. Cobb
Pesticide phytotoxicity and residue accumulation can sub-
stantially reduce poinsettia quality Eleven foliar pesticides
(acaricides, insecticides, and 
fungicides) were evaluated 
for
phytotoxicity and residue accumulation on leaves and bracts
of three poinsettia cultivars (V-14 White, V-14 Glory, and V-
10 Amy Red).
Poinsettias were potted August 3, 1983, and grown in 7 1/2-
inch pots in an amended pine bark-peat moss (3:1, volume ba-
sis) growth medium. Standard cultural and nutritional prac-
tices were followed. Beginning September 30, foliar
applications of the treatments outlined in table 24 were made
biweekly for 8 weeks.
Vendex, a contact acaricide, was phytotoxic to V-14 Glory
bracts only (circular spotting). It was safely applied to the
other two cultivars; however, residue accumulation was
heavy. Pentac, an acaricide with residual activity, was slightly
phytotoxic to the foliage of all cultivars and slightly more phy-
totoxic to the bracts (pinpoint and irregular spotting), but left
no residue.
Meta-Systox R, a contact and systemic insecticide, was
phytotoxic to leaves of both V-14 cultivars (irregularly shaped
light brown lesions); similar, but less severe phytotoxicity was
observed on V-14 Glory bracts. No phytotoxicity was ob-
served on V-10 Amy Red and no residue accumulated on any
cultivar. Orthene, a contact and systemic insecticide with
limited residual activity, resulted in phytotoxicity on foliage
of both V-14 cultivars (cupping, distortion, and marginal
chlorosis). V-10 Amy Red was not damaged by Orthene and
residue accumulation was light. A third insecticide, Diazinon
AG 500, which has contact and stomach poison activity, was
phytotoxic to leaves and bracts of both V-14 cultivars (irreg-
ular lesions, bleached out bracts). Slight leaf injury was ob-
served on V-10 Amy Red. Spray residue was not visible on any
cultivar.
TABLE 24. PESTICIDE PHYTOTOXICITY AND RESIDUE ACCUMULATION ON POINSETTIA
V-14 White V-14 Glory V-10 Amy Red
Pesticide Rate per
Pesticide100 gal. Leaf 
Bract Residue Leaf Bract 
Residue Leaf Bract Residue
injury injury injury injury injury injury
Vendex 50WP .............. 0.5 lb. OKI OK X
2  
OK X X OK OK X
Pentac Aquaflo .............. 5 pt. C
3  
X OK C X OK C C OK
Meta-Systox R 2EC .......... 2.0 pt. X OK OK X C OK OK OK OK
Orthene75SP .............. 1.0b. X OK OK X OK OK OK OK OK
Diazinon AG 500 EC ........ 1.0 pt. X C OK X X OK C OK OK
Ornalin50WP ............... 75lb. C X X X X X C C X
Rovral50WP ............... 1.0 lb. OK OK X OK OK X OK OK X
Daconil2787F ............. 2.0pt. OK X X OK X X OK X X
Kocide 101 77WP ........... 1.0 lb. OK OK X OK OK X OK OK X
Benlate50WP .............. 1.0 lb. OK OK X OK OK X OK OK X
Zyban75WP ............... 1.51lb. OK OK X OK OK X OK OK X
IOK = acceptable quality.
2
X = unacceptable quality.
3
C = apply with caution.
[30]
Unsightly residue accumulations were experienced with all
fungicide treatments. Ornalin, a contact fungicide, was phy-
totoxic to foliage and bracts of all three poinsettia cultivars
(irregular blotching). Daconil 2787 Flowable, a preventative
fungicide with relatively long residual activity, was phytotoxic
to the bracts of all cultivars (dark, irregular spots and light le-
sions). Rovral, a broad-spectrum fungicide, and Kocide 101, a
copper hydroxide compound, resulted in no phytotoxicity,
nor did the systemic fungicides Benlate and Zyban.
Clearly, pesticide phytotoxicity varies among poinsettia
cultivars, with V-10 Amy Red being generally more tolerant
than the two V-14 cultivars. Residue accumulation was sub-
stantial with fungicides; however, applications made early in
the production cycle should not reduce plant quality After
bract formation, extreme caution should be exercised with
any pesticide application. Good cultural practices, fungicidal
drenches, exothermic formulations, and granular insecticide
application will control most disease and insect problems,
minimizing the need for foliar pesticide applications.
See color plates numbers 22-25.
Chemical Control of Fungus Gnats
James C. Stephenson
Fungus gnat, Bradysia coprophila (Linter), larvae live in
the upper surface of poorly drained and frequently irrigated
soil, feeding on soil fungi and organic matter. While larvae
will occasionally feed on plant roots, the main concern in
controlling the insect is to eliminate the impression of poor
sanitation projected by large numbers of adults flying
around plants. This study was conducted to evaluate several
pesticides and application methods, table 25, for control of
fungus gnats in container media.
Rhododendron x Hershey's Red azaleas were placed un-
der 47 percent shadecloth in a glass greenhouse and watered
TABLE 25. CHEMICAL CONTROL OF FUNGUS GNATS
Mean emerging
Insecticide Appl. 
Rate per adults
method 
100 gal. 
water Week 
1 Week 
2
Ro 13-5223 25WP
3 . . . . . . ..
D 1 0 lb 5.8c
4  
0.4a
4
Ro 13-5223 25WP......... D .5 lb. 5.5bc .2a
Diazinon AG 500 4EC .... D 1.0 pt. .8a .3a
Diazinon AG 500 4EC .... D .5 pt. .7a .2a
Diazinon AG 500 4EC .... S 1.0 pt. 1.2ab 1.8a
Orthene 75S ............ D .7 lb. 7.3c 1.2a
Orthene 75S ............ S .7 lb. 3.3abc 1.8a
Control ................. - 6.2c 5.2b
'Applied March 9, 1983; dry bulb 74F, wet bulb 60'F.
2
D = 250 milliliter drench; S = foliar spray application to run-off with
hand-pumped, compressed air sprayer.
3
MAAG Agrochemicals, Vero 
Beach, Florida 32960.
4
Mean separation within columns by Duncan's multiple range test, 5
percent level; values followed by the same letter are not statistically
different.
frequently to promote infestation. After several weeks, in-
fested plants were selected and treated. Treatments were
replicated six times, randomized, and pots individually
caged with paper cylinders covered with tulle to limit gnat
movement. Control was determined by trapping adults with
Olsen Yellow Sticky Traps, 1.4 x 1.6 inches. Data reflect
control of larvae and eggs present at time of treatment ap-
plication.
Diazinon AG 500 applied as a drench at two rates and as
a spray effectively controlled fungus gnats within 1 week
after application. Ro 13-5223, an insect growth regulator
(IGR), applied as a drench provided no control during week
1; however, excellent fungus gnat control was obtained at
both application rates at week 2. Slow response is charac-
teristic of most IGR's. Some control was observed with Or-
thene at week 2. No significant difference between drench
and foliar spray application of Diazinon or Orthene was ob-
served. This may be attributed to a thorough foliar applica-
tion with a significant amount of material contacting the soil
surface. No phytotoxicity was observed with any treatment.
[31]
AUBURN UNIVERSITY
W\ith anII 'aglLI
'Serves tite nleeds of
field crop, livestock.
forestl\ 'I nd hor > il\
twcultural pr()duuers
ill C"Ich regtiont inl
Aldaama. Ew ct\~ itt-
Zen1 (f the 'Statc lu's a
stake inl this researchL
prog Igrain sinee 1an\
adx in1taige frol nt ex\
anid utoreI- euonloni
jil \\a\ 5 of produ(ILC
Ing anld handling
tarn]11 prIoduLcts di 
?
rec tl\ helleits, the
COnTSLIn1ing puLhuiC.
?Main Agricultural Experiment 
Station, Auburn.
SE. V. Smith Research Center, 
Shorter.
1 ,Tennessee Valley Substation, Belle Mina.
2. Sand Mountain Substation. Crossville.
3 North Alabama Horticuiture Subsiation, Cullman
4 Upper Coastal Plain Subsiation, Winfield.
5 Foresiry Unii, Fayette County.
& Chilton Area Horticulture Subsiation, Clanton.
7. Forestry Unuit, Coosa County.
8. Piedmont Subsiation, Camp Hill.
9. Plant Breeding Unii, Tallassee.
10. Forestry Unit, Autauga County.
11. Prattville Experiment Field, Prattville.
12, Black Belt Substation, Marion Junction.
13, The Turnipseed-Ikenberry Place, Union 
Springs.
14. Lower Coastal Plain Substaiion, Camden.
15. Foresiry Unit, Barbour County.
16, Monroeville Experiment Field, Monroeville.
17, Wiregrass Substation, Headland.
18. Brewton Experiment Field, Brewion.
19, Soion Dixon Forestry Education Center,
Covingion ano Escambia counties.
20. Ornamental Horticulture Substation, 
Spring Hill.
21. Gulf Coast Substation, Fairhope.