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Higher Nitrogen Rates Needed for
Black Belt Corn
The potential for nitrogen (N) losses
from runoff and denitrification during
wet weather on calcareous, clavev soils
of Alabama's Black Belt region is great.
Because of this, some corn producers
with a high yield potential in this area
routinely use higher N rates than the
Auburn University Soil Testing
Laboratory recommends (120 pounds
N per acre for nonirrigated corn).
Results of an on-farm Alabama
Agricultural Experiment Station study
conducted in Hale County since 1989
seem to agree with the decision to use
higher N rates. The study evaluated
nitrogen rates, sources, and time of ap-
plication for nonirrigated 
corn grain
production on a calcareous, Black Belt
soil (Vaiden clay).
Sources of fertilizer N used in the
study included ammonium nitrate,
urea, ammonium sulfate, 32 percent
nitrogen solution, and a premium grade
ammoniated granular blend in a 1:1:1
N-1'
2
05-K
2
0 ratio (13-13-13). There
were no differences among fertilizer
sources. Sulfur and potassium were not
yield limiting factors at this site.
Excessive rainfall in the springs of
1989 and 1991 resulted in low yields
due to excessive denitrification in satu-
rated soils and some N runoff loss
when sidedress N was applied. The
standard N rate of 120 pounds per acre
EFFECT OF NI
GflAIN
was not adequate. Highest
yields of 91 and 102 bush- N
els per acre 
for 1989 and 
source'
1991, respectively, were
produced when at least 150 i Rates of F
pounds N per acre were
AN
applied in split 
applications. 
AN
In 1990, yields were AN
limited only by slight AN
moisture stress 
during the 
Time of N
AN
critical silking 
period, see 
AN
table. Nevertheless, grain AN
yields of 132 bushels per AN
AN
acre were produced with
Sources c
160 
pounds 
N per 
acre 
ap- 
AN
plied either as a sidedress AS
application 
at the V10 
Urea
UAN
growth stage or in a split 13-13-13
application at planting 
and 
1
AN=ar
at V10. Increasing 
N rates percent ur
to 240 pounds did not sig- cronutrient
nificantly 
increase 
grain 
nitrate at s
yield. There were no yield
differences among sources of fertilizer
N.
The results of this study suggest
that at least 160 pounds N per acre mav
be needed for corn grain production on
calcareous, Black Belt soils. As with
other Alabama soils, Black Belt soils
delivered best response when N was
applied in split applications with at
least one-third at planting and the re-
mainder in one or more sidedress
TROGEN RATES, SOURCES, AND TIME OF APPUCATION ON CORN
YIELD ON A CALCAREOUS VAIDEN CLAY, 1990 AND 1991
Total Time of N 
Grain yield/acre
N rate application 1990 1991
Lb. Bu. Bu.
0
120
160
200
240
application
160
160
160
160
160
fN
160
160
160
160
160
2-split
2-split
2-split
2-split
planting
2-split
3-split
sidedress
silking
2-split
2-split
2-split
2-split
2-split
95 80
132 98
- 98
137 78
- 70
imonium nitrate: AS=ammonium sulfate; UAN=32
ea ammonium nitrate solution; 13-13-13 (with mi-
s) was applied at planting followed by ammonium
idedressing.
applications. Based on these tests, even
on these fine-textured soils, applying all
of the N at planting appears to be risky.
Corn grain yield was significantly
correlated with N concentration and
chlorophyll measurements in ear-
leaves at silking and with leaves at V10
growth stage. Data suggest a need for
additional fertilizer N if leaf chloro-
phyll reading is less than 44 SPAD at
V10 or at silking.
C.C Mitchell and P.L. Mask
LowELL T i 7. ' ' A AB*'A
N
of
RESEARCH UPDATE
1992
GRAIN CROPS
Alternative Practices Promising for
Annual Ryegrass Control in Wheat
Wheat producers can control an-
nual ryegrass in wheat using the
herbicide Hoelon?. However, there
are potential drawbacks to using this
herbicide, including the possibility that
restricted-use herbicides such as
Hoelon are more likely to have regis-
trations canceled by EPA. Since there
are no other selective herbicides avail-
able to replace Hoelon, research is
needed to develop alternative control
practices that will reduce the damaging
effects of ryegrass on wheat. Such
alternatives are being sought in Ala-
bama Agricultural Experiment Station
research.
Cultural practices that have poten-
tial for reducing the effects of ryegrass
in wheat include tillage, planting date,
and row spacing. These practices have
been used in integrated weed manage-
ment systems of other crops and have
proven to be of considerable value.
Also, nonselective herbicides, such as
Gramoxone? (paraquat), can substi-
tute for tillage.
The objectives of the AAES re-
search were:
1. Determine the effects of des-
troying annual ryegrass flushes either
mechanically (conventional tillage) or
chemically (stale seedbed) prior to plant-
ing wheat.
2. Determine the effects of row
spacings and planting dates of wheat
on control of annual ryegrass.
The above factors were integrated
into systems (with and without Hoelon)
and evaluated at Tallassee in 1990-91.
Ryegrass seeds were sown at 100
pounds per acre to simulate a heavy
population of annual ryegrass. These
seeds were added to an area where
ryegrass seeds already infested the
soil. Wheat variety for both planting
dates was Coker 9766. Seeding rate for
wheat was 15 seeds per foot of 8-inch
rows and 10 per foot of 4-inch rows.
Fertilization and pest control were
provided for adequate wheat yield.
Mechanical or chemical elimina-
tion of annual ryegrass prior to plant-
ing wheat in October resulted in 47 to
66 percent annual ryegrass control
when rated in April. The same treat-
ments with the addition of Hoelon re-
sulted in 98 percent control and wheat
yield that averaged 31 percent more.
The 4-inch row spacing produced a
slight increase in ryegrass control, but
a slight decrease in grain yield at the
October planting. Wheat lodging was a
significant problem at this early plant-
ing with the Coker 9766 variety planted
in 4-inch rows. The alternative proce-
dures were generally unacceptable at
this planting date.
Eliminating annual ryegrass
chemically with Gramoxone and plant-
ing the wheat in December into a stale
seedbed combined to give ryegrass con-
trol at the April rating that averaged 90
percent for the 8-inch row spacing and
93 percent for the 4-inch 
row. However,
wheat yield averaged 23 percent higher
for the 4-inch row spacing. The addi-
tion of Hoelon to these late imple-
mented systems proved to be detrimen-
tal to wheat yield, although rvegrass
control was slightly higher. Lodging
was not a problem when the wheat was
planted late in the 4-inch row. Chemi-
cally eliminating ryegrass flushes with
Gramoxone and planting wheat late
to 4-inch rows into a stale seedbed
shows good potential as an alternative
procedure for annual ryegrass control
in wheat.
R.H. Walker
Increasing Nitrogen and Using Strip Tillage Can Boost
Tropical Corn Yields
Tropical corn is a promising new
crop that may fit well into some crop-
ping systems in the Southeast. Since it
is a new crop, there is limited informa-
tion available to describe its response to
tillage and soil fertility. A field study
was initiated at the Wiregrass Substa-
tion in 1990 to evaluate tropical corn
response to nitrogen (N) and starter
fertilizer when grown under conven-
tional and reduced tillage systems.
Conventional tillage consisted of
chisel plowing and disking followed
by in-row subsoiling at planting. Strip
tillage consisted of planting corn into
wheat stubble after in-row subsoiling.
Nitrogen was applied at 
rates of 0, 50,
100, and 150 pounds per acre. Five
starter treatments, consisting of various
combinations
of N, phospho-
rus (P), and
sulfur (S), also
were tried: (1)
no starter; (2)
20 pounds N
per acre; (3)
20 pounds P
per acre; (4)
20 pounds N
and 20 pounds P per acre; and (5) 20
pounds N, 20 pounds P, and 10 pounds
S per acre.
In 1990, Pioneer X304C was grown
and grain yields were not determined
due to severe insect damage. Insect
pressure, however, did not limit silage
yields. Excellent silage yields were ob-
tained with the conventional and strip
tillage systems averaging 17.1 and 20.3
tons per acre, respectively. Silage yields
were increased by the addition of N
and starter fertilizer. The use of the N
and P starter increased silage yields by
3.1 tons per acre.
continued on page 3
TROPICAL CORN SILAGE AND GRAIN YIELDS (AVERAGED OVER STARTER TREATMENTS) AS
AFFECTED BY RATE OF NITROGEN FERTILIZER UNDER CONVENTIONAL AND STRIP TILLAGE, 1991
Nitrogen Silage yield/acre 
Grain yield/acre
rate/acre, lb. Conventional Strip 
Mean Conventional Strip Mean
Tons Tons Tons Bu. Bu. Bu.
0 ........... ...... 6.8 6.3 6.6 26 29 28
50 ....... ............ 9.0 10.7 9.8 46 62 54
100 .................. 10.9 12.0 11.4 56 74 65
150 ................... 11.6 13.3 12.5 60 81 71
New Tropical Corn Varieties Examined for
Alabama Production
In recent vears there has been sub-
stantial interest in utilizing tropical
corn hybrids in Alabama. 
In general,
tropical corn is not replacing conven-
tional corn hybrids, but is being planted
instead of silage sorghums. There also
is interest in tropical corn as a grain crop
to follow small grains or as a grain crop
that is able to utilize the nitrogen fixed
by winter legume cover crops.
Little information is available re-
garding the potential and management
of tropical hybrids for Alabama, and
Pioneer X304C has been the most
widely available commercial hybrid.
Therefore, an Alabama Agricultural
Experiment Station study was con-
d ucted to compare 10 hybrids for silage
and grain production to see if other
hybrids have production potential in
Alabama.
The hybrids were planted on three
different dates at Belle Mina, in the
Tennessee Valley, on a Decatur silt
loam. The earliest planting date in the
study was mid-May, to fit in a silage or
double-cropping system. If corn is
planted before May, then hybrids
adapted to temperate climates will
Nitrogen and Strip Tillage, continued
The experiment was continued in
1991 using Pioneer 3072, a high grain
yielding tropical corn variety. Grain
yields in 1991 ranged from 26 to 81
bushels per acre. Silage and grain yields
increased with N rate, with consistently
higher yields and a greater response to
added N occurring under strip tillage.
The best starter treatment for si-
lage was the N and P (NP) treatment,
which produced an average of 11 tons
per acre, see table. For grain, N alone
as a starter gave the same yield as the
NP starter, with the greatest response
occurring under conventional tillage
(increase of 26 bushels per acre when
averaged over N rates). Initial results of
this test indicate that tropical corn is a
promising alternative source of silage
and grain for Alabama farmers.
G.L. Mullins, S.E. Alley. and D.W. Reeves
yield more grain
than tropical hy-
brids.
For grain pro-
duction, the opti-
mum planting
date for north
Alabama was
mid-May to June
1. Optimum plant-
ing dates for cen-
tral and south
Alabama would
likely be 1 to 2
RANKING OF TROPICAL CORN VARIETIES FOR SILAGE AND GRAIN PLANTED JUNE 1 AT
BELLE MINA, 1990
Brand and hybrid Silage Rank Grain 
Rank
yield/acre yield/acre
Tons Bu.
Pioneer X304C .............. 22 1 11 6
DeKalb 678C ................. 18 2 14 7
Pioneer 3098 ................. 18 3 15 5
Pioneer 3078 ................. 14 4 27 4
Pioneer 3214 ................. 11 5 15 6
Pioneer 3210 ................... 11 6 32 3
Pioneer 6875 ................... 8 7 33 2
Pioneer 3072 .................. 6 8 52 1
weeks earlier. Early planting was es-
pecially critical for grain production.
In 1990, for example, grain yield for
the Pioneer 3072 was 73, 52, and 35
bushels per acre when planted May
17, June 1, and June 21, respectively.
When planting for silage, early
planting is not as critical. The hybrids
tested varied considerably in their suit-
ability for silage or grain production
and their yield response to planting
date, see table. Pioneer X304C and 3098
and DeKalb 678C were top silage pro-
ducers, yielding 22, 18, and 18 tons per
acre, respectively, in the dry year of
1990.
Pioneer 3072 and 3210 were the best
grain producers, averaging 73 and 64
bushels per acre when planted May 17.
Overall, hybrids that yielded well for
grain did not yield 
well for silage,
while hybrids that yielded well for
silage did not yield well for grain.
This study indicated that Pioneer
X304C and some of the hybrids that are
not currently commercially available
have great potential as an alternative
double-crop for Alabama farmers.
However, more research is needed on
control of fall army worm before the
full potential of this crop can be real-
ized.
P.L. Mask and D.W. Reeves
Head scab of wheat caused by
Fusarium species occurs sporadically in
humid regions where wheat is grown.
Scab is best recognized on emerged
immature heads where one or more
spikelets or the entire head appears
prematurely bleached. Small, black
structures (fungal fruiting bodies) and
pink or orange mycelium may be seen
at the base of diseased spikelets. Grain
from scab-infected wheat may contain
mycotoxins that can induce vomiting
in humans and other nonruminant ani-
mals.
In Alabama, weather conditions in
the winter and spring of 1990 were con-
ducive for scab development. Sterility
and poor grain fill due to scab resulted
in an estimated 40 percent yield de-
crease in infected fields. Current Ala-
bama Agricultural Experiment Station
research is evaluating means of creating
artificial Fusarinum epidemics while si-
multaneously evaluating fungicides
for control. One way of creating artifi-
cial epidemics is by injecting plants
with the pathogen.
Field experiments were conducted
at the Sand Mountain Substation and
the Tennessee Valley Substation during
the 1990-91 growing season. Fusariiml
occurrence on heads was increased by
simulating frost damage to wheat dur-
continued on page 4
Pesticides Evaluated for Scab
Epidemics on Wheat
Tropical Corn Shows Potential for
Conservation Tillage Systems
The late 
planting
date of tropical corn
allows more flexibility
than temperate corn
for double-cropping
with winter annual
legumes. Using tem-
perate corn with a
winter legume re-
quires yearly costs of
EFFECT OF A WINTER COVER CROP ON GRAIN YIELD, AVERAGED OVER N RATE AND
APPLICATION TIME
1991 grain yield/acre
Winter cover crop 
Shorter Crossville
X304C 3072 X304C 3072
Bu. Bu. Bu. Bu.
Fallow . ......................... 39 57 45 67
Crimson clover .................. 51 85 76 105
labor, machinery, seed, and chemicals
to plant and kill the legume in time to
plant temperate corn. A conservation
tillage system with tropical corn would,
however, eliminate these costs and maxi-
mize the advantages of the winter an-
nual legume.
In the past, Pioneer X304C was the
only widely available commercial
tropical corn hybrid. Grain yields of
this hybrid have been disappointing.
Results from varietv trials, however,
indicate that Pioneer 3072 has a higher
grain yield potential than Pioneer X304C.
Results of joint Alabama Agricul-
tural Experiment Station and USDA-
ARS field experiments at the E.V. Smith
Research Center, Shorter, and the Sand
Mountain Substation, Crossville, illus-
trate the advantages of using tropical
corn and crimson clover in a conserva-
tion tillage system.
Four years ago, the plot area was
either left fallow or seeded to crimson
clover in the fall. Clover naturally re-
seeded every year thereafter. Tropical
corn hybrids Pioneer X304C and 3072
were planted into the fallow area and
the clover residue in Jmune 1991. Four
nitrogen (N) rates (0, 45, 90, and 180
Pesticides Evaluated, continued
ing anthesis by applying dilute
amounts of paraquat. Studies in the
lab showed that tebuconazole pro-
vided better control against growth of
Fusarium, but this fungicide was
not as effective as benomyl or
triadimenol for control in the field.
However, plots treated with tebu-
conazole had highest yields and low-
est levels of mycotoxin contamination.
K.L. Bowen. D.J. Collins, and P.L. Mask
pounds N per acre) were applied either
at planting or split with one-third ap-
plied at planting and the remainder 5
weeks later.
Crimson clover, compared to fal-
low, increased grain yield of Pioneer
X304C and 3072 an average of 53 per-
cent, see table. Split N applications,
however, had no effect on grain pro-
duction and the effect on silage produc-
tion was variable. When averaged over
both locations, silage yields of Pioneer
3072 tended to decrease while those of
Pioneer X304C tended to increase
when the N rate was split.
The hybrids responded differently
to N rate for both silage and grain pro-
duction. At both locations, Pioneer 3072
increased silage production with each
additional increment of N applied.
Maximum yield was 20 and 24 tons per
acre at Shorter and Crossville, respec-
tively, with 180 pounds of N per acre.
Pioneer X304C, however, reached its
silage yield potential (17 and 22 tons per
acre at Shorter and Crossville, respec-
tively) at the 45-pound N rate and
did not significantly increase in
yield with additional N applied at
either location.
The same trends existed for both
hybrids in grain production. Yield po-
tential of Pioneer 3072, however, was
much greater than that of Pioneer
X304C. At Crossville, yields of Pioneer
3072 peaked at 124 and 104 bushels per
acre following clover and fallow, re-
spectively, with 180 pounds N. At
Shorter, yields peaked with the 90-
pound N rate, averaging 87 and 72 bush-
els following clover and fallow, respec-
tively. Pioneer X304C, on the other
hand, did not respond as well to N
applicationsbeyond 90poundsperacre,
especially at Shorter.
The high yield potential of newer
tropical corn hybrids such as Pioneer
3072, when grown in a conservation
tillage reseeding clover system, indi-
cate it may be an economical and
environmentally sound alternative
cropping system.
R.C. Kingery and D.W. Reeves
Government Program, Crop Insurance, and
Options Reduce Corn Producer's Income Risk
Government program participa-
tion, commodity options, and Multiple
Peril Crop Insurance are management
methods that can be used to reduce
price and production risks. A recent
Alabama Agricultural Experiment Sta-
tion study estimated the riskiness of
using alternative combinations of these
strategies to produce and market 100
acres of corn on a representative north
Alabama farm.
Returns exceeding variable costs
were calculated for each combination
of farm program participation, crop in-
surance, and commodity option possi-
bilities on the 100 acres. Flex crops
considered were corn, soybeans, and
cotton. Farm financial performance
was charted for 5 years with 500 dif-
ferent combinations of possible yields
and prices per year.
The results showed that participa-
tion in the farm program provided
higher returns than not participating.
Also, participation at the 15 percent flex
level with commodity options and crop
insurance generally provided the high-
est returns with the least financial risk.
The alternative with the least finan-
cial risk was found to be participation in
the farm program with a 15 percent
continued on page 5
Traffic and Tillage Systems Influence
Corn Production
The need to manage soil compac-
tion, along with new regulations for soil
conservation in the 1985 and 1990 Farm
Bills, has led to the need to examine
tillage practices on coarse-textured
Coastal Plains soils for corn production.
The interaction of tractor traffic and
tillage on corn yields was studied in a
joint Alabama Agricultural Experiment
Station/USDA-ARS project at the E.V.
Smith Research Center, Shorter. Plots
with varying tillage and tractor traffic
treatments were planted on 30-inch rows
following a legume winter cover crop.
Treatments consisted of the following :
Deep tillage. No subsoiling, an-
nual in-row subsoiling, or a one-time
complete disruption of the hardpan in
1988.
Surface tillage. Leaving winter
cover crop residue on the surface or
harrowing and field cultivating before
planting.
Income Risk, continued
soybean flex, and with commodity op-
tions and crop insurance. With this
least-riskcombination, the estimated net
present value of returns for 5 years
averaged $62.13 per acre.
Participation in the 15 percent and
25 percent flex programs provided
higher returns than those received
where there was no government pro-
gram participation. In general, 15 per-
cent flex alternatives provided higher
net returns than did 25 percent flex al-
ternatives for comparable levels of in-
surance and options participation.
Purchasing crop insurance pro-
vided higher minimum returns than
comparable noninsured alternatives
(probability of less than the minimum =
0). The minimum net present value
with crop insurance ranged from -$0.63
per acre (25 percent cotton flex) to $21.49
per acre (25 percent soybean flex).
Growing cotton on the 15 percent
flex acres, without insurance, provided
the highest net present value of returns
(probability of less than $123 per acre -
100 percent). On the average, however,
a producer was better off to purchase
Tractor traffic. Normal tractor traf-
fic with the use of 4-row equipment or
removal of all tractor traffic from plots
(use of wide-frame research vehicle that
spanned corn rows for necessary till-
age).
Soil moisture was monitored
throughout the growing season and
corn yields were measured at harvest.
In addition, soil compaction measure-
EFFECT OF TRACTOR TRAFFIC AND TILLAGE SYSTEMS ON CORN Y
Tillage
Deep tillage
No deep tillage ...............
Annual in-row subsoiling ...
Complete disruption ..........
Surface tillage
Harrow/field cultivation......
No surface tillage ..............
Corn yield/acre, by tra
Normal traffic N
Bu.
131
135
crop insurance and options (probability
of less than $66 per acre = 50 percent).
For a farmer who chooses not to
participate in the farm program, pur-
chasing crop insurance and commodity
options provided higher average,
minimum, and maximum values than
did purchasing insurance alone or not
purchasing insurance and options. The
average net present value of returns per
acre (probability of getting less than
expected returns = 50 percent) with no
government program participation
ranged from $38.93 with no insurance
to $41.62 with insurance and options.
The best individual strategy de-
pends on how much of a risk the pro-
ducer can stand. The most profitable
high risk strategy was to plant corn with
a 15 percent cotton flex crop, without
crop insurance or commodity options.
The best risk neutral strategy found
was corn with a 25 percent cotton flex.
Finally, the risk averse strategy of
choice was corn with a 15 percent soy-
bean flex crop.
J.L Novak. RG. Nelson, and W.R. Goodman
ments at different depths were made
with a penetrometer.
The test covered 4 years, including
2 years of drought (1988 and 1990) and
2 years of abtmdant rainfall (1989 and
1991). With both complete disruption
and in-row subsoiling, yields in the
drought year of 1988 were greatest
when vetch residue was not incorpo-
rated by surface tillage; how ever, when
deep tillage was not performed, sur-
face tillage increased yields.
With favorable rainfall in 1989,
there was no beneficial effect of surface
residues as in 1988. FHow-
'IELD, 1991 ever, yields againincreased
ctor traffic with the 
intensity of deep
tillage, and surface tillage
o traffic increased yields when 
no
Bu. deep tillage was per-
formed. In the extreme
134 drought year of 
1990,
135 
corn yields 
were se-
142
verelv limited, with a
140 maximum 
yield of only
135 28 bushels per acre. In that
year, yields decreased
with intensity of tillage.
After 4 years, the effect of tractor
traffic was dependent on 
tillage system,
see table. When tractor traffic was re-
moved, highest yields resulted from
surface tillage or from the one-time
complete disruption of the hardpan;
however, when normal tractor traffic
was used and caused 
recompaction,
these same treatments resulted in the
lowest yields. Therefore, in the absence
of traffic, residual effects of tillage per-
formed 4 years previously still im-
proved yields. With traffic, annual
subsoiling still maintained yields near
the top.
Data indicate that an intensive till-
age system followed by tractor traffic
resulted in greater recompaction of the
soil, which restricted root growth.
Results from this study suggest that
the conservation tillage practice of in-
row subsoiling without incorporating
residues is an appropriate practice for
sustaining corn yields on Coastal Plains
soils, especially if traffic patterns can be
maintained so that at least one row
middle adjacent to each row receives
no traffic during the growing season.
H.A. Torbert and D.W. Reeves
Insecticides May Have Use in Hessian Fly Management on Wheat
Experiments on chemical control
of Hessian fly have been conducted dur-
ing the past several years throughout
the State. Experimental wheat plots
were planted at five locations on two
different dates (late September and
early November). The locations were:
Black Belt Substation, Marion Junction;
Wiregrass Substation, Headland; Gulf
Coast Substation, Fairhope; Tennessee
Valley Substation, Belle Mina; and Up-
per Coastal Plain Substation, Winfield.
Each treatment consisted of either
Saluda, Coker 9766, or Florida 302
wheat cultivars treated with either dis-
ulfoton or phorate. In previous tests,
Saluda proved to be resistant to Hessian
fly, Coker 9766 was moderately
resistant, and Florida 302 was suscep-
tible to this pest. Insecticides were ap-
plied in-furrow at planting at 0.75
pound active ingredient per acre. Hes-
sian fly counts and yield determina-
tions were made at harvest.
Severe weather conditions and
heavy wheat disease incidence pre-
cluded data collection at several plant-
ing dates and locations. The table shows
the combined yield data from all plots
harvested. Although no statistical dif-
ferences were present, the yields from
insecticide treatments were usually
slightly higher than those from check
plots. Coker 9766 was consistently
the highest yielding cultivar of the
three evaluated. This difference cannot
be explained by Hessian fly control be-
cause this pest was not present at all
locations.
EDITORWS No)I L
Metntion of Ocompany 0or trade ;ames does not
indicate endorsement by the Alabama Agricul-
tural Experiment Station or Auburn Unziversitiy of
oe bramlt over aiothcr. Aiy mention of iionllabel
uses or applications in excess of labceled rates of
pesticides or other chiinicals does not con.stitute a
recon cdatio11. Such use in research is simply
part of thc scientific investigation n'cessary 
to fidly
ecaltate nmat'rials and treatnents.,
Informatioul cotaiii ed herei is lavailabhl to all
prsonI s ithout rcard 
to rac, color, srx, orI ational
origill.
COMBINED GRAIN YIELD 1989-90
Yield, bu/acre
Treatment Gulf Coast 
Wiregrass Upper Coastal 
Average
Substation Substation Substation
Insecticide
Check ............................. 22.33 37.40 15.33 25.02
Disulfoton ..................... 23.41 37.16 16.59 25.72
Phorate ............... .......... 23.29 41.88 16.38 27.19
Cultivar
C9766 ..................... 29.56 55.24 13.64 32.81
FL 302 .......................... 12.46 33.41 15.57 20.48
Saluda ................ ......... 7.80 27.79 19.10 18.23
Low but consistent Hessian fly
numbers did occur at the Gulf Coast
Substation following the first plant-
ing. Hessian fly counts at harvest
indicated that at least two times as
many pupae were found in the check
plots as in the treated plots. However,
this difference was not reflected in the
vields. Saluda and Coker 9766 had
fewer pupae than Florida 302, although
vields were not related to fly numbers.
Overall, Coker 9766 proved to be a good
yielding variety even under unfavor-
able conditions.
Past experiments have indicated
that insecticides have limited use in
management of Hessian fly; however,
these results do suggest that this avenue
should be explored further.
P.M. Estes
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