RESEARCH RESULTS FOR FLOWER CROVERS
Azalea Studies 1966 - 1969
Kenneth C. Sanderson, William E. Barrick,
Willis C. Martin, Jr., and Raymond L.Self
Horticulture Series No. 13
AGRICULTURAL EXPERIMENT STATION
OF
AUBURN UNIVERSITY
E. V. Smith, DirectorAuut16AbrnAlaa August 1969 Auburn, Alabama
I. Influence of Commercial Root-Inducing Substances and 2,4,5-T on the
Rooting of Azalea Cuttings, cv. 'Red Wing'. (Sanderson)
Cuttings of the azalea cultivar, 'Red Wing', were treated by dipping the
base of cuttings in either commercial root-inducing 
substances, a 5 p.p.m.
solution made from the herbicide 2,4,5 trichlorophenoxyacetic acid (2,4,5-T)
and its derivatives, or a 40 p.p.m. solution of 2,4,5-T and its derivatives.
The root-inducing substances and respective rooting scores are presented in
Table 1.
Table 1. Influence of Several Commercial Root-Inducing
Substances and 2,4,5 Trichlorophenoxacetic Acid
on Rooting of Azalea, cv. 'Red Wing'.
Rooting substances Active ingredient/ Rooting score3
Check .... . .............. .. . 2.8
Hormodin No. 1 .......... IBA 2.4
Hormodin No. 2 .......... IBA 2.6
Hormodin No. 3 ......... IBA 2.6
Rainbow Tender ......... 2,4,5-T & NAA 2.4
Rainbow Woody ......... 2,4,5-T & NAA 
2.6
Rootone ......... NAA, NAAA & IBA 1.9
Rootone No. 10 ......... NAA, NAAA & IBA 0.6
2,4,5-T 5 p.p.m. ........ 2,4,5-T 2.4
2,4,5-T 40 p.p.m. ........ 2,4,5-T 
2.6
1/ Manufacturers of the commercial root-inducing substances are: 
Merck &
Company, Inc., Rahway, N. J., Hormodin No. 1, 2, 3; Rainbow Color and
Chemical Company, Northbridge, California, Rainbow Tender and 
Rainbow
Woody; Amchem Company, Ambler, Pa., Rootone and Rootone No. 
10. The
2,4,5-T solutions were prepared from the herbicide 2,4,5 trichlorophenoxy-
acetic acid.
2/ IBA = Indole butryic acid, 2,4,5-T = Trichlorophenoxyacetic acid, NAA =
Napthaleneacetic acid, NAAA = Naphthylacetamides.
3/ Rooting scores are based on: 0 = no rooting, 1 = light rooting, 2- medium
rooting, 3 = heavy rooting.
Use of commercial root-inducing substances did not influence the ultimate
rooting of 'Red Wing' azalea cuttings. Untreated cuttings yielded the highest
rooting score (2.8 out of a possible 3.0) indicating that the cultivar 'Red Wing'
will root well without the use of a root-inducing substance. Certain commercial
materials gave the poorest rooting score, but generally yielded similar scores
(2.4 - 2.6). Root-inducing substances may have influenced the time required for
rooting. The earliest rooting time was observed in cuttings treated with 2,4,5-T.
II. Effect of Cuttings Taken from Growth 
Retardant Treated Plant on the
Rooting of Azalea, cv. 'Red Wing'. 
(Sanderson)
Stock plants on the azalea 
cultivar 'Red Wing' were 
sprayed with a 0.25
per cent spray of the growth retardant succinic 
acid 2,2-dimethylhydrazide
(B-Nine, trade mark of Uniroyal Company). 
Cuttings were removed from the
plants at intervals of 2, 5 and 7 days following 
spraying. A check, consist-
ing of cuttings taken from untreated plants was also 
provided. Cuttings taken
from retardant-treated stock plants rooted 
as well as the cuttings from untreated
stock plants. There was no difference in the sprayed 
cuttings taken at various
intervals following spraying.
III. Effect of a Fungicide Dip on the Propagation of 
Azalea, cv. 'Red Wing' in
Unsterilized Media. (Sanderson)
An unsterilized media consisting of equal parts of soil and peat moss was
used as a propagation media. Cuttings of the azalea cultivar 'Red Wing' were
given the following basal treatments: (1) check (no treatment), 
(2) Ferbam,
(3) Hormodin No. 2, and (4) 1:1 Ferbam and Hormodin No. 2. Heavy rooting was
observed with all treatments. Rooting scores (0 = none, 1 
- light, 2 = medium
and 3 = heavy) were as follows: Check - 2.8, Ferbam -
2.9, Hormodin No. 2 -
2.8 and 1:1 Ferbam-Hormodin No. 2 - 2.9. Although 
Ferbam has been reported to
inhibit rooting of certain woody plant species, 
this was not the case with
'Red Wing' azalea.
IV. Influence of Several Growth Regulating Substances 
on Rooting of Azalea,
cv. 'Coral Bells' and cv. 'Red Wing'. (Sanderson 
and Martin)
Root-induinducing treatments were prepared 
from 10 growth-regulating substances
by diluting the material with a small amount 
of alcohol and making up to volume
with water. The materials are listed in Table 
2 along with a check and two
commercial root-inducing substances. The 
concentration of the prepared solutions
was 20 p.p.m. for all the substances except Gibberellic 
acid, which contained
1,000 p.p.m. Treatment consisted of dipping 
1/2 inch of base of the cutting
in the solution for 5 seconds. The commercial 
materials were in talc form and
the cuttings were dipped, then immediately 
removed from these materials. Cuttings
of the cultivars 'Red Wing' and 'Coral 
Bells' were used.
The results are presented in Table 2. Most 
of the treatments yielded
a high percentage of rooting with the exception 
of 2,4,5-TP, 2,4,5-T, and
2,4-D. Hormodin No. 2, IAA, indole propionic 
acid and P-chlorophenoxy acetic
acid gave best rooting percentages for 
'Coral Bells'. 'Red Wing' had high
rooting percentages with all the substances 
except 2,4,5-TP, 2,4,5-T and 2,4-D
yielding low scores. 'Coral Bells' 
cuttings gave the best rooting scores 
when
cuttings were dipped in Hormodin No. 
2, IAA and P-chlorophenoxy acetic acid.
'Red Wing' cuttings rooted well with 
no treatment or all the materials 
except
2,4,5-TP, 2,4,5-T, and 2,4-D. Hormodin 
No. 2 and IAA gave the best combined
rooting score for the two cultivars.
Table 2. Influence of Several Growth-Regulating Substances on the
Rooting of Azalea, cv. 'Red Wing' and cv. 'Coral Bells'
Treatments Per cent rooted 
Rooting score
'Red 'Coral 'Red 'Coral
Wing' Bells' Wean Wing' Bells' MeC-
Check (no treatment)....................... 100 70 8 2.7 
1.7 2.2
0-chiorophenoxy acetic acid................. 100 75 8 
2.6 198 2.2
P-chlorophenoxy acetic acid............... 
95 8 92 2.3 2.2 
2.3
2,4,5 Trichlorophenoxrpropionic 
acid (2,4,5-TP). 18 28 
23 0.2 0.7 0.5
2,4,5 Trichlorophenoxy 
acetic acid (2,4,5-T) o. 
28 48 30.3 
1.0 0.7
2,4 Dichiorophenoxy acetic acid 
(2,4-D) ... 65 73 69 
1.1 1.7 1.4
3 lndole propionic acid ......................100 85 93 2.6 1,8 2.2
Indole butryic acid (IBA)................. .....100 78 89 2.6 1.6 2.1
Indole 3 acetic acid (IAA).................. 100 85 93 2.7 2.2 2.5
Gibberellic acid 10% K salt............... 100 83 92 2.5 1.7 2.1
Hormodin No. 1.................................100 80 90 2.7 1.9 2.3
Hormodin No. 2............... ............ 100 93 98 2.5 2.5 2.5
j All treatments consisted of 20-p.p.m. concentration with the exception of
gibberellic acid which was a 1,000 p.p.m. concentration. Hormodin No. 1 and
No. 2 are the products of Merck & Co., Rahway, N.C. Active ingredient is
indole butryic acid.
R Booting scores are based on 0 = no rooting, 1 - light rooting, 2-medium
rooting and 3 = heavy rooting.
V. Influence of Various Chemical Treatments on the Growth and Cold Hardiness
of Three Azalea Cultivars. (Sanderson and Self)
A test on cold damage to azaleas was begun with a group of container grown
plants in the field on November 1, 1967 at the Spring Hill Ornamental Horticulture
Field Station. A second test was begum December 20 on 'Coral Bells', 'Pink Supreme',,
and 'Coral-Bells Supreme' azaleas.
Treatments consisted of foliage sprays (1) check, water; (2) 2.38 per cent
Potassium bromide (KBr), 2.18 per cent calcium chloride (CaCl
2
) plus 1.5 per cent
potassium nitrate (KNO3); (3) treatment 2 plus 0.01 per centnapthleneacetic acid
(NAA); (4) treatment 2 plus 0.25 per cent succinic acid 2,2-dimethylhydrazide (B.
Nine); (5) treatment 2 plus 0.01 per cent indole acetic acid (IAA); (6) treatment 2
plus 0.01 per cent maleic hydrazide; (7) 0.05 per cent salicylic acid (aspirin);
(8) 0.28 per cent 2-chloroethyl trimethylammonium chloride 
(Cycocel); (9) 0.25
per cent B-Nine; (10) 12.5 pei? cent Wilt Pruf; (11) 25.0 per cent Wilt Pruf;
(12) 1/2 tsp. KNO
3
/No. 6 can; (13) 1/2 tsp. 120-6.-4/No. 6 .can; and (14) 1/4 tsp.
Suipho-mag/No. 6 can.
Day temperature for three weeks prior to treatment of test 2 had been in the
seventies with nights in the fifties. On December l9,,,the high was 8~0 degrees.
The plants were in a new flush of growth when the temperature dropped to 240 F.
on December 23. The next day the temperature was 281 F. and on the 29th and 30th,
the temperature was 310 F.0
an
4.
In the first test the KBr, CaC12, and KN0
3 
combinations burned the
foliage of 'Pink Ruffles' azaleas.
Top weights of plants in test 2 were taken May 10, 1968 after the first
flush of growth. Per cent changes in top fresh weight from check are presented
in Table 3.
Table 3. Per Cent Changes in Top Fresh Weight
from Check of Azaleas Receiving Various
Chemical Treatments, May 10, 1968
Treatment ''Coral 'Pink 'Coral Bells
Bells' Supreme' Supreme' Mean
Check . . . . . . . . . . -
KBr, CaC12, KNO
3 
spray . . . . -60 00.0 -25.0 
-28.3
KBr, CaC12, KNO3, NAA spray . . +60 +16.6 
-37.5 +13.7
KBr, CaCl
2
, KN03, B-Nine spray. -60 +16.6 -37.5 -26.9
KBr, CaC12, KN03, IAA spray . . -60 -16.6 -37.5 -38.0
KBr, CaC12, KNO
3
, MH spray . -80 00.0 -37.5 -39.2
Aspirin spray . . . . . . -80 +16 6 -12.5 
-25.3
Cycocel spray . . . . . . . . +20 00.0 +12,5 +0.8
B-Nine spray ..... ,. . -20 +50.0 00,0 +10.0
12.5% Wilt Pruf spray . . . . . -20 +50.0 +25.0 
+18.3
25.0% Wilt Pruf spray . . . +20 +66.6 -12.5 +24.7
1/2 tsp. KN03 per can . . . . -40 +500 +12.5 
+ 7,5
1/2 tsp. 12-6-4 per can . . . . -20 00.0 
-25o0 -15.0
1/4 tsp. sulpho-mag per can . . -20 +66.6 
00.0 +15,5
1/ Treatments applied December 20, 1967
VI. Preliminar Experiments on the Chemical Pinchin of Azaleas. (Sanderson and
Preliminary experiments on chemLical pinching of azaleas were conducted
during 1967 at the Ornamental Research Field Station in Springhill and two
commercial nurseries in Semmes, Alabama. The two chemical pinching agents,
Emery C-9 (Emery Industries', designation for methyl nonanoate) and P & G (Off-
shoot-O) manufactured by Proctor and Gamble), have been evaluated at various
concentrations on a number of plant species. The pinching agents were usually
applied with an electric mist blower and permitted to remain on the plant for
10 minutes before being washed off,
Springhill Experiments: Eperiment 1.
The chemical pinching agents, Emery C-9 and Proctor and Gamble, were
applied at 3 per cent and 6 per cent concentrations with a small electrically
driven mist blower and washed off 10 minutes later with water. Hand pinched
(sheared) plants were used as a check. The following cultivars were 
used in
the experiment: 'Alaska', 'Coral Bells', 'Hinodegiri', 'Pink Supreme' and 'Red
5
Wing'. All plants were grown 
in a shaded greenhouse under the 
prevailing
weather conditions. Treatments were applied 
on June 16, 1967.
The terminal buds of the azaleas were observed to turn brown within a
few minutes after treatment with the pinching agents. The 
buds were visibly
dead within 24 hours. A foliage burn occurred at the higher concentrations
on some cultivars. New lateral shoot development began on some treated culti-
vars within two weeks. Certain cultivars were successfully pinched with con-
centrations of 3 to 6 per cent. Table 4 shows results for several cultivars
treated at the Springhill Station. Chemical pinching produced fewer shoots
than manual pinching in the cultivars 'Alaska', 'Pink Supreme' and 'Red Wing'.
More shoots were observed with chemical pinching than manual pinching in the
cultivars 'Chimes', 'Coral Bells', and 'Hinodegiri'. The 6 per cent concen-
tration produced more shoots than the 3 per cent concentration but damaged
the plant. Foliage damage was most severe with the 6 per cent Emery C-9.
Table 4. Effect of Chemical Pinching Agents on the Mean Number of Lateral
Branches per Eight Inch Stem, Springhill Experiment
Cultivars Pinching treatments
Emery C-9 Offshoot-O Hand pinch (sheared)
3% 6% 3% 6% No treatment
'Alaska'....... . 1.5 1.9 1.9 1.7 4.2
'Chimes,' ....... 2.5 2.8 2.6 2.5 
2.4
'Coral Bells',. .... 3.9 6.1 5.0 5.9 2.1
'Hirodegiri'. .... 2.9 6.5 6.5 5.9 4.8
'Pink Supreme'. ... 3.5 3.4 3.2 
4.8 5.3
'Red Wing'....... .. 1.4 2.5 1.5 1.7 4.5
Mean. ........ ... 2.6 3.9 3.5 3.8 3.8
Experiment 2.
Three per cent P and G chemical pinching agent sprays were applied to
'Alaska' azaleas and washed off ten minutes later. Treatments were applied
September 25 and November 4, 1967 with a high volume, low pressure sprayer.
Counts were made on the number of new branches per 5 new stems per plant. The
per cent increase in lateral branches 6 weeks later as a result of the treat-
ments was 53.8, 65.3, and 69.0 for three separate groups of 5 plants.
Experiment 3.
Emery C-9 and P and G pinching agents were applied at 6 per cent concen-
trations, and Ortho 991 (a fungicide that exhibited some pinching activity) at
a 1 lb./l00 gal. concentration, and washed off 10 minutes later. Plant material
included 'Red Wing' and 'Chimes' azaleas. Six months after treatment a bloom
count per 6 plants and new shoot growth on 5 stems per 5 plants were determined
and are presented in Table 5 and Table 6.
Table 5. Change in Number of Flowers as Compared with
Unsheared Plants on Chemically Pinched Azaleas
Treatment Change from unsheared check
'Red Wing' 'Chimes'
6% P & G .. . ................. . +2.9 -8.1
6% Emery ........ ................ +4.3 -18.9
Ortho-991 ................ .- 8.6 -24.3
'Table 6. Change in Number of New Shoots on Chemically Pinched
Azaleas as Compared to Sheared Azaleas
Treatment Change from unsheared check
'Red Wing' 'Chimes'
6% P & G ....................... +26.7 +264.2
6% Emery C-9 ..................... +28.5 +221.4
Ortho-991 1 lb./gal. ............... -12.4 +200.0
Treatment at this time obviously destroyed many of the flower buds. If
plants are to be developed further vegetatively, the use of a disbudant at this
time would be highly desirable.
Experiment 4.
Proctor and Gamble disbudant was applied at 3 per cent, 4 per cent and
6 per cent concentrations and not washed off. Three applications were made to
'Red Wing' azaleas with new growth.
A count of the number of new shoots per eight-inch stem was determined
seven weeks after the third treatment (July 29, 1968). The per cent increase
over that of the checks is given in Table 7.
7
Table 7. Per Cent Change in the Number of Shoots per Eight-Inch 
Stem on
Chemically Pinched Azaleas Compared to Unsheared Azaleas
Treatment Change from unsheared check
3% P & G ...... ............... ........ +75
41% P & G . ....... ..................... . . +117
6% P & G................................... +182
The 3 per cent rate of application produced satisfactorily headed plants,
but the 6 per cent rate of application produced most compact, slightly smaller
plants with the possibility of the most blooms.
Semmes Experiments:
Experiments on chemical pinching were conducted on field grown azaleas at
two commercial nurseries in Semmes, Alabama, Blackwell Nurseries, Inc., and Tom
Dodd Nurseries, Inc. An electric mist blower was used to apply a 3 per cent mist
of the two chemical pinching agents, Emery C-9 and Proctor and Gamble. Plants
were washed with water 10 minutes after application of the pinching agent. One-
gallon plants of the cultivars 'Alaska', 'Coral Bells', 'Hinodegiri', 'Pink
Supreme', 'Red Wing' and 'Sweetheart Supreme' were treated at Blackwell Nurseries,
Inc. The check consisted of sheared plants. Treatments were applied on June 15,
1967. Two-gallon plants were used at Tom Dodd Nurseries, Inc. The cultivars
'Coral Bells', 'Evensong', 'Hersey Red', 'Hexe', 'Hinodegeril, 'Morning Star',
'Pink Supreme', 'Red Wing', 'Sweetheart Supreme' and 'Snow' were treated with
the chemical pinching agents on June 16, 1967. Unsheared plants served as a
check.
Results of experiments conducted in Semmes, Alabama are presented in
Table 8. Although some cultivars produced more shoots when chemically pinched,
the mean number of shoots for chemically pinched one-gallon plants was little
different from the shoot number for sheared plants. Considering the two-
gallon plants, the cultivars 'Evensong' and 'Hershey Red' showed a definite
response to chemical pinching.
VII. Influence of Chemical Pinching Agents Applied with and without B-Nine
on Four Cultivars of Azaleas. (Sanderson, Martin and Barrick)
Four cultivars of azaleas, 'Gloria', 'Coral Bells', 'Red Wing' and
'Anytime received the following treatments on July 15, 1968: (1) sheared,
(2) sheared plus 0.15 per cent B-Nine, (3) 4 per cent Emgard 2077, (4) 4 per
cent Offshoot-O, (5) Emgard 2077 combined with 0.15 per cent B-Nine, (6) 4 per
cent Offshoot-O combined with 0.15 per cent B-Nine. All treatments were applied
with a mist blower. Plants were grown in a shade house until forcing. Fertili-
zation and other cultural practices were kept as uniform as possible. Data on
the number of breaks per shoot and plant height was taken on March 26, 1969.
Ten shoots were examined on five plants in each treatment for breaks per
shoot. The height above the pot rim of the tallest shoot was recorded on
five plants per treatment.
Table 8. Response of Several Azalea Cultivars of One-Gallon and
Two-Gallon Size to Chemical 
Pinching /
Mean number of breaks per shoot
Cultivar One-gallon Two-gallon
Emery C-9 P & G sheared Emery C-9 P & G Unsheared
3% 3% 3% 3%
Alaska'......... ... 2.5 2.7 2.7 .......-
'Coral Bells' . .... 2.5 3.1 2.6 3.2 3.5 2.1
'Evensong'. . ........--- --- -- 5.4 4.2 .8
'Hershey Red' ..... .--- -- --- 3.7 3.8 1.5
'Hexe'. .......... ..--- --- -- 1.2 2.3 1.1
'Hinodegiri'. ...... . 2.8 2.9 3.4 4.5 3.9 4.2
'Morning Star' . -- -.--- --- 2.7 2.4 1.9
'Pink Supreme'..... . 2.4 2.4 2.3 2.2 2.3 1.9
'Red Wing'. ....... .. 3.0 2.2 2.5 2.4 1.8 1.1
'Sweetheart Supreme' . 3.0 2.7 2.0 2.4 2.4 .8
'Snow'. .......... ...--- --- --- 2.9 2.2 2.3
Mean ........... ... 2.7 2.7 2.6 3.1 3.1 2.0
One-gallon plants sprayed at
gallon plants sprayed at Tom
ation of these two nurseries
Blackwell Nurseries, Inc., 
Semmes,
Dodd Nurseries, Inc., Semmes, Ala.
is gratefully acknowledged.
Ala. Two-
The cooper-
Plants receiving growth retardants were darker green in color and had
shorter shoots. In some cultivars the combination of a chemical pinching agent
and a growth retardant produced a very desirable, compact plant. In the
cultivar 'Coral Bells' the shoot growth was so compact that measurement of shoot
number was difficult. The treatments did not seem to influence flowering time.
The four cultivars produced as many or more breaks per shoot when pinched
chemically than when sheared, Table 9. The mean number of breaks for shearing
(2.6) was less than the number of breaks produced by chemical pinching. The
two chemical pinching agents averaged approximately the same number of breaks
per shoot. Offshoot-0 produced more breaks per shoot when combined with B-Nine
(3.2) than when sprayed alone (2.8). The addition of B-Nine did not influence
9
the mean break production for Emgard 2077. B-Nine did not seem to have any
effect on the number of breaks per shoot as the untreated (2.8) and treated
(2.9) plants were essentially equal.
Table 9. Influence of Chemical Pinching Agents Applied with and
without B-Nine on the Number of Breaks per Shoot
Treatments Cultivars
'Anytime' 'Coral Bells'Gloria'Red Wing' Mean
Sheared .............. 2.6 2.7 2.4 2.5 2.6
Sheared plus B-Nine ......... 2.6 2.5 2.4 
2.5 2.5
4% Emgard .... ............ .2.9 3.2 3.2 2.8 3.0
4% Offshoot-0O .... .......... .2.6 
3.2 2.6 2.6 2.8
4% Emgard plus 0.15% B-Nine .... 2.8 3.0 3.4 2.8 3.0
4% Offshoot-0 plus 0.15% B-Nine .. 3.2 
3.2 3.5 2.9 3.2
Mean .......... ....... 2.8 3.0 2.9 2.7 2.9
Table 10 shows that B-Nine influenced the height of the plants. The mean
height of untreated plants (29.1 cm) exceeded the mean height of B-Nine treated
plants (27.4 cm). Shearing plus B-Nine produced the shortest mean height. The
application of either of the chemical pinching agents without B-Nine produced
the tallest plants (mean 29.7 cm). The combination of Emgard 2077 and B-Nine
(27.7 cm) yielded a mean height less than the sheared treatment (27.9 cm) and
any chemical treatment.
Table 10. Influence of Chemical Pinching Agents Applied with and
without B-Nine on the Height of Plants (cm) Above the Pot Rim
Treatments Cultivars
'Anytime' 'Coral Bells' 'Gloria' 'Red Wing' Mean
Sheared .. .............. .. 29.2 30.1 26.7 25.4 27.9
Sheared plus B-Nine . . . . . . . . 26.4 26.0 28.4 26.4 26.4
4% Emgard 2077 ........... .. 35.0 30.2 26.4 27.7 29.4
4% Off-Shoot 0 .... .......... .30.9 32.7 29.3 28.4 30.3
4 Emgard 2077 plus 0.15% B-Nine . . 30.1 28.6 25.2 26.7 27.7
4% Offshoot-O plus 0.15% B-Nine . . 33.0 28.9 26.9 27.7 29.1
Mean ....... ................ 30.8 29.4 27.2 27.1 28.5
VIII. Influence of Chemical Pinching Agents Used in Combination with Manual
Shearing on the Azalea Cultivars, 'Red Wing' and 'Chimes'. (Sanderson,
Barrick and Martin)
The azalea cultivars, 'Red Wing' and 'Chimes' were treated on September
5, 1968 as follows: (1) sheared, (2) not sheared, (3) 4.1 per cent Emgard 2077,
(4) 4.1 per cent Offshoot-0, (5) 2.05 per cent Emgard 2077 and 2.05 per cent
Offshoot-0, (6) sheared, 4.1 per cent Emgard 2077, (7) sheared, 4.1 per cent
Offshoot-0, (8) sheared, 2.05 per cent Offshoot-0. Chemical pinching agents
10
were applied with a low pressure, high volume hand sprayer. Six plants were
used per treatment. The experiment was conducted in a greenhouse. 
The
number of breaks was determined for 10 shoots on each plant.
The cultivar 'Chimes' showed excessive leaf injury from the chemical
pinching agents. Damage is believed to be a result of the 
cupping nature
of Chimes leaves, an application of too much material and excessive 
concen-
tration.
Chemical pinching produced a mean of 2.8 breaks per shoot 
in comparison
to 2.4 breaks produced by shearing, Table 11. Offshoot-0 
with or without
shearing averaged the most breaks (2.9) per shoot. 
Emgard 2077 and the
combination of Emgard and Offshoot-0 produced 
the same mean number of breaks
per shoot (2.7). Applying the chemical pinching agents 
to sheared plants
decreased the mean number of breaks on 'Red Wing' (2.8 
for unsheared vs. 2.6
for sheared) but increased the mean number of breaks 
per shoot on 'Chimes'
(2.6 for unsheared vs. 2.9 for sheared). 
The mean number of shoots for
unsheared and sheared, chemically pinched plants was 2.7 and 2.8 respectively.
Table 11. Influence of Chemical Pinching Agents Used 
in Combination
with Manual Shearing on the Number of Breaks per Shoot
on the Azalea,cv. 'Red Wing' and 'Chimes'
Treatment Cultivar
'Red Wing' 'Chimes' Mean
Sheared . ....... . 2.5 2.3 2.4
4.1% Emgard 2077 .............. 
2.7 2.5 2.6
4.1% Offshoot-0O .. ............ 
3.1 2.6 2.9
2.05% Emgard 2077 & 2.05% Offshoot-0 . ... 2.6 2.8 2.7
Sheared plus 4.1% Emgard 2077 .......... ... 2.5 2.9 2.7
Sheared plus 4.1% Offshoot-0..... . . ..2.7 
3.2 2.9
Sheared plus 2.05% Emgard 2077 & 2.05%
Offshoot-0 . . . 2.7 2.7 2.7
Mean ............................... .... 2.7 2.7 
2.7
IX. Influence of Chemical Pinching Agents 
on Sheared and Unsheared Azaleas,
cv. 'Red Wing'. (Sanderson, Barrick and Martin)
Tests were conducted to determine the effects 
of chemical pinching agents
on sheared and unsheared 'Red Wing' azaleas. Two chemical agents, Enmgard 2077
at 4.1 per cent and Offshoot-0 at 4.1 per cent, and a combination 
of the two at
2.05 per cent each were used. Application of the 
chemical pinching agents was
done on September 30, 1968 using the Emgard 
Sprayer with 2.9 oz. or 86 ml. of the
chemical agent mixed with water to fill a quart volume. 
The eight treatments,
using six plants per treatment, were as follows:
11
(1) Check - not sheared.
(2) Check - sheared manually.
(3) Spray Emgard 2077 at 4.1 per cent not 
sheared.
(4) Spray Emgard 2077 at 4.1 per cent sheared.
(5) Spray Offshoot-0 at 
4.1 per cent not sheared.
(6) Spray Offshoot-O at 4.1 per cent sheared.
(7) Spray Emgard 2077 at 2.05 per cent and Offshoot-0 
at 2.05 per cent not
sheared.
(8) Spray Emgard 2077 at 2.05 per cent and Offshoot-0 at 2.05 per cent
sheared.
All plants were grown in a greenhouse at a temperature of 700 F. A
monthly fertilizer program consisting of 2 pounds of 21-7-7 soluble fertilizer
per 100 gallons was used. The plants also received on application of 12-6-6
granular fertilizer with 2 per cent Di-Syston at the rate of 1 teaspoon per
pot. Data was taken on five plants in each treatment. The number of breaks
per shoot was determined on ten shoots per plant.
Plants sprayed with chemical pinching agents (3.0) averaged more breaks
per shoot than manually sheared plants (2.,8). When treated with a chemical
pinching agent, (3.2) unsheared plants yielded more breaks per shoot than sheared
plants (2.9). The combination spray of 2.05 per cent Emgard and 2.05 per cent
Offshoot-0 (3.3) yielded the most breaks per shoot of the experiment when applied
to unsheared plants. The mean number of shoots produced by Offshoot-0 (3.2)
exceeded that of Emgard 2077 (3.0) and the combination (2.9).
Table 12. Influence of Chemical Pinching Agents Applied to
Sheared and Unsheared Azaleas, cv. 'Red Wing',
on the Number of Breaks per Shoot
Spray treatment Shear treatment Mean
None Sheared
None . . . a. . . . . . . . . . .. . . . . --- 2.8 2.8
4.1% Emgard 2077 . . . . . . . . . . . . . 3.1 2.9 3.0
4.1% Offshoot-0 . . . . . . . . . .. 3.1 3.2 
3.2
2.05% Emgard 2077 & 2.05% Offshoot-0 . . . 3.3 2.6 2.9
Mean . . . . . . . . . . . . . .. . . . 3.2 2.9 3.0
X. Effect of Chemical Pinching Agents Plus Growth Retardants on Azalea, cv.
Tests were conducted to determine the effects of chemical pinching agents
plus growth retardants on Red Wing azaleas. Emgard 2077 (4.1%) and Offshoot-0
(4.1%), chemical pinching agents, were used in combination with growth retardants,
B-Nine (0.15%) and UNI (0.05%). Application of the chemical pinching agents and
growth retardant combinations was done on September 30, 1968, using the Halaby
mist blower. The nine treatments using six plants per treatment were as follows:
12
(1) Check - sheared.
(2) Check - sheared and sprayed with 0.15 per cent B-Nine.
(3) Check - sheared and sprayed with 0.05 per cent UNI-F 529
(4) Emgard 2077 at 
4.1 per cent.
(5) Emgard 2077 at 4.1 per cent plus 0.15 per cent B-Nine.
(6) Emgard 2077 at 4.1 per cent plus 0.05 per cent UNI-F 529
(7) Offshoot-0 at 4.1 per 
cent.
(8) Offshoot-0 at 4.1 per cent plus 0.15 per cent B-Nine.
(9) Offshoot-0 at 4.1 per cent plus 0.05 per cent UNI-F 529
All plants were grown in a greenhouse under uniform cultural conditions.
Fertilization consisted of both liquid (21-7-7 at the rate of 3 pounds per 100
gallons each month) and dry (one application of 12-6-6 with 2 per cent Di-Syston
at the rate of 1 teaspoon per pot) fertilizers. The number of breaks on ten
shoots per plant was recorded on March 18, 1969.
Table 13 shows that plants pinched with 
4.1 per cent Offshoot-0 (3.3)
averaged more breaks per shoot than plants pinched with 4.1 per cent Emgard
2077 (2.8) or sheared plant (2.7). The growth 
retardant UNI-F 529 (2.7)
yielded fewer breaks per shoot than the untreated check (2.9). The combination
of 4.1 per cent Offshoot-0 and 0.15 per cent B-Nine (3.8) produced 
the most
breaks per shoot. Shearing plus 0.05 per cent UNI (2.5) and 4.1 per cent
Emgard 2077 (2.5) gave the fewest number of breaks per shoot.
Table 13. Effect of Chemical Pinching Agents Combined with Growth
Retardants on the Number of Breaks per Shoot on
Azalea, cv. 'Red Wing'.
Pinching treatment 
Growth retardant Mean
None 
0.15 per cent 
0.05 per cent
B-Nine UNI-F 529
Sheared ............... . 2.9 2.8 2.5 
2.7
4.1% Emgard . . . ...... . . 2.5 2.9 2.92.8
4.1% Offshoot-0 . ........... 3.2 3.8 2.8 3.3
Mean . . . . . . . . . . . . ... . . . 2.9 3.1 2.7 2.9
XI. Influence of the Type of Sprayer on the Effectiveness of Chemical Pinching
Agent, cv. 'Red Wing'. (Sanderson, Barrick and Martin)
Tests were conducted on Red Wing azaleas to see the effectiveness of two
methods of applying chemical pinching agents. Emgard 2077 and Offshoot-0 were
both applied with the Halaby mist blower and with the Sovereign sprayer. The
seven treatments using six plants per treatment were applied on September 30,
1968 as follows:
(1) Check - sheared.
(2) Emgard 2077 at 4.1 per cent - Sovereign sprayer.
(3) Emgard 2077 at 4.1 per cent - Halaby mist blower.
(4) Offshoot-0 at 4.1 per cent - Sovereign sprayer.
(5) Offshoot-0 at 4.1 per cent - Halaby mist blower.
(6) Emgard 2077 at 2.05 per cent plus Offshoot-0 at 2.05 per cent - Sovereign
sprayer.
13
(7) Emgard 2077 at 2.05 per cent plus Offshoot-O at 2.05 per cent - Halaby
mist blower.
The experiment was conducted in a greenhouse at a temperature of 700 F.
Fertilization consisted of a monthly application of 21-7-7 soluble fertilizer at
the rate of 3 pounds per 100 gallons.
Differences in the number of breaks per shoot between mist (2.2) and spray
(2.3) applications of chemical pinching agents were not distinguishable, Table 14.
Offshoot-O (2.2), Emgard 2077 (2.3) and the combination of the two (2.3) pro-
duced approximately the same number of breaks per shoot. The best chemical
pinching treatments were the 4.1 per cent Emgard 2077 spray (2.5) and the com-
bination of 2.05 per cent Emgard 2077 and 2.05 per cent 
Offshoot-O mist (2.4)
sheared plants (2.9) produced more breaks per shoot than chemically pinched
plants (2.3).
Table 14. Influence of Chemical Pinching Sprays and Mists on
the Number of Breaks per Shoot on Azalea, cv. 'Chimes'
Number of breaks
Treatment per shoot
Sheared ......................... 2.9
4.1% Emgard 2077 spray ..... ................. 2.5
4.1% Emgard 2077 mist . .................. 
2.1
4.1% Offshoot-O spray....... .
............ 2.2
4.1% Offshoot-O mist ..............
2.1
2.05% Emgard 2077 & 2.05% Offshoot-0 spray ...... 2.2
2.05% Emgard 2077 & 2.05% Offshoot-O mist 
. ....... 2.4
Mean . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4
XII. Influence of Photoperiod on Shoot Growth of Azalea,- cv. 'Coral Bells'.
(Sanderson)
On May 24, 1968, 18 azaleas; cv. 'Coral Bells', were pruned so that each
shoot had only 3 nodes. All shoots having less than 3 nodes were removed. The
plants were placed in a growth chamber at a night temperature of 700 F. and a
day temperature of 800 F. Photoperiod treatments consisted of a 9-hour day, 9-
hour day plus 2 hours of incandescent light in the middle of the night and a 9-
hour day plus 4 hours of incandescent light in the middle of the night. An
automatic watering system supplied the plants with 4 oz. of water at each watering
early in the experiment. As the plants grew, the amount of water per watering was
increased to 6 oz. Fertilization consisted of monthly applications of 25-10-10
fertilizer at the rate of one teaspoon per gallon of water. The mean number of
shoots and shoot length were recorded on July 23, 1968.
The mean number of shoots per stem for the 9-hour day, 9-hour plus 2 hours
at night and 9-hour day plus 4 hours at night were 4.3, 4.0 and 3.7 shoots
14
respectively. Plant which received 2 hours of light in the middle of the night
(9.0 cm) produced longer shoots than plants grown on a 9-hour day (8.2 cm) or a
9-hour day plus 4 hours of light in the middle of the night (6.7 cm).
XIII. Influence of Temperature and Photoperiod on the Grcmath of -A ezn .IE
'Kingfisher'. (Barrick and Sanderson)
The influence of temperature and photoperiod on the growth of the azalea
cultivar 'Kingfisher' was studied in a growth chamber experiment. 
Two chambers
with minimum night temperatures of 950 F. and 650 F., respectively were employed.
Day temperatures were maintained ten degrees above the night temperatures. Photo-
period treatments at each temperatule consisted of a 9-hour day, a 9-hour 
day
plus 4 hours of incandescent light in the 
middle of the night and a 9-hour day
plus 15 hours in incandescent light. 
A light intensity of 5,000 f.c. was 
pro-
vided by flourescent and incandescent sources during the day. Supplemental
incandescent light had an intensity of approximately 40-55 f.c. at the plant
level. Temperature and photoperiod treatments were started on December 5, 1968.
Plants of the cultivar 'Kingfisher' were obtained through the courtesy of
Yoder Brothers, Barberton, Ohio and potted in six-inch pots. German peat moss,
amended with 56 g of limestone and 56 g of gypsum was used in potting. Plants
were sheared prior to treatment. An automatic watering system was used to water
the plants. A setting of 4 oz. per watering was used early in the experiment.
The setting was increased to 6 oz. as the plant grew. Fertilization consist of
21-7-7 at the rate of 3 pounds per 100 gal. every two weeks. A teaspoon of 2
per cent Di-Syston impregnated 12-6-6 fertilizer was applied to the plants during
the first month of the experiment. The number of breaks per shoot and shoot length
was determined in March, 1969.
Plants grown in the 950 F. chamber exhibited severe chlorosis on new
growth. Developing leaves were a creamy white color. Growth in the 650 F. chamber
was not chlorotic. Table 15 indicates that higher growth temperatures (950 F.)
may influence the number of breaks produced by a shoot following shearing. Photo-
period treatments did not seem to influence break numbers. A combination of
the 950 F. temperature and the 9-hour day (2.3) yielded the most breaks. Con-
tinuous lighting (9-hour day plus 15 hour) and the 650 F. temperature (1.9)
produced the smallest number of breaks per 
shoot. Plants grown at 950 F. (7.6 cm)
showed onlay a slight increase in break length over plants grown at 65' F. (7.4 cm).
Photoperiods of 9-hour plus 15-hours of light (8.6 cm) produced the longest breaks.
Breaks on plants grown. on a 9-hour day (6.5 cm) were shortest in length. 
A com-
bination of 9-hour day plus 650 F. or 950 F. temperatures produced the 
longest
breaks. The shortest breaks were produced on a 9-hour day at either 650 F. 
or
950 F.
15
Table 15. Influence of Temperature 
and Photoperiod on the Number of
Breaks per Shoot and Break Length of Azalea, 
cv. 'Kingfisher'
Photoperiod 
Temperature Mean
650 F. 950 F.
Number of breaks per shoot
9-hr. day .. .. ............... ..
2.1 2.3 2.2
9-hr. day plus 4 hr . . . ...... 
2.0 2.1 2.1
9-hr. day plus 15 hr............ 
1.9 2.2 2.1
Mean . ................. 
2.0 2.2 
2.1
Length of breaks (cm)
9-hr. day ..... ............... .. 6.5 6.4 
6.5
9-hr. day plus 4 hr. ....... .... 7.0 7.0 
7.0
9-hr. day plus 15 hr. ............. 8.6 
8.5 8.6
Mean ........ ................. 7.4 7.6 
7.5
ACKNOWLEDGEMENT
The authors wish to express their appreciation 
to Blackwell Inc., Semmes,
Alabama, Tom Dodd Nurseries Inc., Semmes, 
Alabama and Yoder Brothers, Barberton,
Ohio for their assistance in this research.
Summary
1. Commercial root inducing substances 
did not influence the ultimate
rooting of 'Red Wing' azaleas. Untreated cuttings 
rooted as well
as treated cuttings.
2. Cuttings taken from stock plants 
which had been treated with B-Nine
rooted as well as cuttings taken from 
untreated stock plants.
3. The addition of Ferbam 
to root inducing substances 
did not inhibit
but rather may have increased rooting in unsterilized media.
4. Hormodin No. 2 
and 20 ppm IAA gave 
the best rooting scores 
of a
number of root inducing substances used 
on 'Red Wing' and 'Coral
Bells' azaleas. Several herbicides promoted good rooting, however,
2,4,5 T and 2,4,5 TP gave poor rooting.
5. Applications of cold 
hardiness inducing sprays 
of Cycocel, B-Nine,
Wilt Pruf and a combination of inorganic 
salts plus IAA and a soil
application of sulpho-mag increased the 
top fresh weight of azaleas.
Cold hardiness was not observed because of unusually 
warm weather.
6. Chemical pinching had consistently 
yielded more breaks per shoot than
manual shearing. Cultivars vary in their response 
to chemical pinching
with 'Chimes', 'Coral Bells', 'Red Wing' and 'Hinodigiri' 
giving a
good response. The chemical pinching 
agents Emgard 2077 and Offshoot-0
were effective pinching agents. In six 
out of nine experiments Offshoot-0
produced slightly more breaks per plant 
than Emgard 2077. A 4.0 per cent
concentration has been effective in most cases.
7. Combining 0.15 per 
cent B-Nine with either 
4.0 per cent Emgard 2077 
or
4.0 per cent Offshoot-0 did not influence 
pinching in one experiment but
the combination of B-Nine and Offshoot-0 produced 
the most breaks in another
experiment. The combination produced 
a shorter, more compact plant in both
experiments. The new growth retardant UNI-F 
529 was found to be quite
effective on azaleas.
8. Applying chemical pinching agents 
to sheared plants decreased the number 
of
breaks per shoot.
9. The type of sprayer (mist vs. spray) 
used to apply chemical pinching agents
did not seem to influence the number of breaks 
per shoot when the material
was allowed to remain on the plant.
10. Photoperiod influenced the 
number of breaks per shoot and the 
length of
the breaks in one experiment but not in another. The addition 
of 2-15
hour of supplementary light seemed 
to reduce the number of breaks but
increased the length of the breaks. A 
temperature of 950 F. at night
produced slightly more breaks and longer 
breaks than a temperature of 650
F. at night.
16