Research Update
?A1990
'.. PEANUTS
FIRST IN RESEARCH
UPDATE SERIES ON
PEANUTS
This is the first peanut
research report published in a
new publication series entitled,
"Research Update," which was
inaugurated in 1989 by the
Alabama Agricultural Experiment
Station (AAES). The new series
is meant to promote timely
reporting of iesearch results
dealing with a specific crop or
commodity, with distribution to
all producers of that particular
commodity. In this case, the
target aud:ence is all Alabama
farmers who grow peanuts as a
commercial crop.
Today's highly competitive
conditions make it doubly
important that farmers have
available the latest scientific
i:formation. Publication of this
new series is meant to help meet
that need. Efforts will be made
to maintain up-to-date mailing
lists of each producer group so
all Alabama producers will
receive the appropriate report
annually.
Other information about
peanut production and latest
recommendations are available
from each county Extension
Service office in Alabama.
New Fungicides Affect Varieties
Differently
Both yield and grade of Florun-
ner peanuts were improved by
Spotless@, Folicur?, or Flutolanil?,
when substituted for two of seven
Bravo treatments on a standard 14-
day leafspot spray program. Yield
also was improved on Southern
Runner peanuts, but quality factors
were largely unaffected by using
the new sterol-inhibiting fungicides.
In the Auburn tests, Spotless at
0.2251 pound per acre and Folicur at
0.25 pound per acre were substi-
tuted for the third and fifth Bravo
applications. Flutolanil at 1.0 pound
per acre was tankmixed with the
recommended rate of 1.5 pints per
acre of Bravo and substituted for
Bravo alone, also on the third and
fifth fungicide applications.
All three substitute treatments
reduced the incidence of both
Southern stem rot and limb rot on
both Florunner and Southern Run-
ner peanuts. And, yields were in-
creased 44-49 percent for Florunner
and 24-39 percent for Southern
Runner, compared to using Bravo
on all seven applications.
No differences were found in
sound mature kernels (SMK) among-
ments and varieties. However, Flo-
'All treatment in active ingredients.
ner averaged 24 percent extra large
24 percent extra large kernels 
(ELK),
compared to 18 percent ELK for
Southern Runner. In Florunners,
kernel damage (DK) was 6.1 per-
cent, compared to 1.8 percent of
Southern Runner. In Florunner
peanuts, the addition of Folicur to
the Bravo spray program increased
ELK 5 percent and decreased DK
by 4 percent, while Southern Run-
ner's values were unaffected.
J C. Jacobi and P.A. Backman
-I
Peanut Seed Size Has
Little Effect on Yield
Several sizes of peanut seed are
available to growers. Planting
smaller seed, often referred to as
high count seed, may save growers
up to $30 per acre. However, ques-
tions remain as to how smaller seed
will tolerate production stresses,
such as burn, from herbicides.
Studies conducted in 1989 revealed
that upon germination, smaller seed
resulted in smaller plants-which
was expected. However, these
smaller plants grew at the same rate
A LABAMA AGRICULTURAL EXPERIMENT STATION AUBURN UNIVERSITY
LOWELL T. FROBISH, DIRECTOR AUBURN UNIVERSITY, ALABAMA
i
-$-~ it: "i
as the larger plants from larger
seed. The yield differential be-
tween small, high count seed and
large seed was less than 100 pounds
per acre.
Plants were treated with normal
and excessive rates of Gramoxone?.
As expected, peanut plant growth
was temporarily interrupted as the
damaged leaves were replaced.
However, the growth delay was no
different between the smaller plants
and the larger plants. Seed size had
only a slight effect on yield among
the small, medium, and large seed
used in the test.
Based on this 1-year test, which
was conducted under nearly ideal
weather conditions, it can be con-
cluded that planting the larger seed
simply represents a means to enter
the growing season with somewhat
larger plants. Consequently, the
canopy did close quicker over the
row middles. Whether there are
additional benefits remain to be de-
termined.
GR Wehtje
Lorsban for Control of Lesser Cornstalk Borer
ering to late pegging, but none of the
granular insecticides that are regis-
tered for use in peanuts are labeled
for two applications.
The flowering time application of
Lorsban was more effective for a
longer period of time than the peg-
ging treatment in 1987, and was
equivalent to a pegging time appli-
cation in the other test.
T.P Mack and M.G. Miller
Alternative Crop
Rotations Improve
Peanut Yields
The lesser cornstalk borer is an
economic pest of several crops in the
Southeast, including 
peanuts, corn,
sorghum, and small grains. It is the
most economically damaging insect
pest of peanuts in the Southeast.
Damaging population outbreaks
occur during periods of hot, dry
weather, and are more likely on
peanuts grown in sandy soils.
Lorsban@ is the most commonly
used insecticide to manage lesser
cornstalk borers. Recent AAES stud-
ies measured the residual effective-
ness of Lorsban over time against
lesser cornstalk borers in peanuts,
and compared the performance of
different application times.
Lorsban applied at planting sig-
nificantly reduced survival of lesser
cornstalk borer larvae at 0, 16,22,29,
and 42 days after application. Lar-
val survival was not significantly
different from survival in untreated
plots from 56 to 91 days after appli-
cation. Both treatments containing
planting and pegging applications
reduced larval survival until 36 days
after application. All of the pegging
and flowering treatments signifi-
cantly reduced survival of larvae im-
mediately after application; how-
ever, the activity of each treatment
varied with time. The flowering time
application reduced larval survival
on all days, except one day after
application. The pegging applica-
tion reduced survival at 10, 14, and
43 days after application.
The application of Lorsban for
lesser cornstalk borer control was
effective in Alabama for 42 and 102
days in 1986 and 1987, respectively.
The decreased effectiveness in 1986
was probably caused by accelerated
Lorsban degradation in the hot and
dry weather during the growing
season. The month of July in 1986
had 268 hours in which the hourly
soil temperature 1 inch below the
soil surface was above 95'F, com-
pared to zero hours of such condi-
tions in 1987.
Lesser cornstalk borer damage
occurs primarily during 
flowering,
pegging, and pod production. An
insecticide applied for lesser corn-
stalk borer management must pro-
tect the plant from flowering to late
pod-fill to reduce yield losses. The
planting time application was not
effective during this period in 1986.
The effectiveness of this application
declined when the plants were grow-
ing pods, indicating that significant
pod damage could have occurred.
The planting time application pro-
vided season-long control during
normal moisture and temperature
conditions (e.g., 1987), but not when
hot, dry climatic conditions were
present (e.g., 1986). A planting and
a pegging application reduced lesser
cornstalk borer survival from flow-
Root-knot nematodes are primary
yield-reducingpathogens of peanuts
in Alabama. The banning of effec-
tive and economic soil sterilants by
the EPA has left growers with lim-
ited chemical nematicide options and
no new resistant varieties are ex-
pected in the near future.
One option for reducing nema-
tode populations being tested by the
AAES is the use of alternate crops
that are poor hosts, or in some cases
toxic to nematodes. Cotton, 
sesame,
castor beans, American 
jointvetch,
partridge peas, and hairy indigo are
among the crops being tested in
rotation with peanuts. Comparison
studies included peanuts following
peanuts with no chemical treatment
and peanuts following peanuts in
which Temik? at the rate of 3 pounds
per acre active ingredient (a.i.) was
applied on a 10-inch wide band.
Temik improved yields in both
years of the test, but reduced juve-
nile root-knot nematode counts in
only one year. Sesame improved
peanut yields by about 100 pounds
per acre more than Temik, and cas-
tor beans improved yields by about
200 pounds per acre more than the
Temik-treated peanuts. In the same
test, cotton, partridge peas, and
American jointvetch all produced
about 100 pounds per acre less than
the Temik-treated plots.
In a separate 
test, hairy indigo,
used as a rotation crop, improved
peanut yields by about 300 pounds
per acre over peanuts following
peanuts. The same percentage yield
difference held true when both the
indigo-peanut and peanut-peanut
plots were treated with 3 pounds per
acre a.i. of Temik.
Cotton has become an increasingly
popular crop in the Wiregrass in
recent years. It is doubly popular
because it is not a host crop for root-
knot nematodes. In tests by the
AAES, cotton-peanut plots produced
3,000 pounds per acre, when neither
crop was treated with Temik. When
both crops, both years, were treated
withTemik, yields improved to 3,200
pounds per acre. 
In the same test,
peanuts following peanuts and not
treated with Temik produced 2,600
pounds per acre and peanut-peanut
plots treated with Temik produced
2,800 pounds per acre.
R. Rodriguez-Kabana
Reduced Terrachlor Rates Control White Mold
Terraclor 10G? has been used b
Alabama farmers for a number
years to protect peanuts from whit
mold, though its use has declined i
recentyears. However, recentAAE
Disease Control and Yield Response with Re
Terraclor 10 G on Peanuts
Fungicide
White mold hits/100 ft. of row
1988 1989
No. No.
Terraclor 10G, 100 lb. . 6.7
Terraclor 10G, 50 lb. ... 5.8
Spotless 25W, 1 lb. ..... 3.4
Nontreated control ....... 12.4
research indicates reduced rates
the popular fungicide may provide
better control and allow growers to
reduce cost.
Tests were conducted in 1988 and
1989 in two farm fields with a his-
tory of high peanut yield losses from
white mold. Florunner peanuts
were planted in all fields in early
May and maintained according to
current recommendations. Terraclor
10G was applied at early peg at the
reduced rate of 50 pounds per acre
and full rate of 100 pounds per
acre of formulated product. The re-
duced rate was applied on a 4-inch
band by centering the drop tube
directly over the row, while a 5-inch
bander was used to apply the full
rate on a 12-inch band width.
Over the 2-year period, the re-
'y duced rate 
of Terraclor 10G 
gave
)f equal to slightly better disease con-
te trol than the same fungicide at the
n full label rate. Plots treated with the
S reduced rate yielded an average of
356 pounds per acre
higher than 
those treated
educed Rate of
with the full rate. The ex-
perimental fungicide
Yield Spotless gave superior
1988 1989 
white mold control 
and
higher yields 
both years
Lb. Lb. 
than the full 
rate of Ter-
3,611 3,667 raclor. 
However, similar
3,986 4,004 yields were obtained 
in
4,044 4,331 
the plots 
treated with 
the
reduced 
rate 
of Terraclor
10G and Spotless in 1988.
of Austin Hagan
New Fungicides May
Reduce Peanut
Aflatoxins
Three new fungicides, which soon
may be marketed, showed some
promising effects on decreasing con-
centration of aflatoxin contamina-
tion found in irrigated peanuts
grown in 1988. When these fungi-
cides, Spotless@, Folicur@, and Flu-
tolonil?, were applied to peanut
plants at pegging for control of soil-
borne diseases, seed harvested from
treated plants were shown to con-
tain 11-33 percent less aflatoxin than
kernels from plants treated with rec-
ommended fungicides.
However, in 1989, in peanuts from
unirrigated plots, fungicidal 
appli-
cations did not reduce aflatoxin
concentration. It is assumed the lack
of impact of these experimental
fungicides on aflatoxin concentra-
tion in the second year of testing was
primarily weather related.
Exterior tissue of whole, intact
peanut seed (5-10 percent by weight,
including testa and outer layers of
cotelydonary tissue) have been
shown to contain the majority of
aflatoxin contamination in peanuts
sampled. This may prove to be a
method by which aflatoxins can be
removed.
K.L. Bowen
Integrated Pest
Management Program
Being Developed
for Peanuts Pests
AU-Pnut, Auburn University
Peanut pest management 
program,
is being developed to help farmers
manage nematodes, 
fungal diseases,
and insect pests of peanuts. The
program is using an "expert sys-
tem" approach which allows incor-
poration of qualitative reasoning as
well as quantitative analysis. The
expert system also has the advan-
tage that the reasoning behind rec-
ommendations can be displayed to
inform users about integrated pest
management concepts.
To arrive at a recommendation,
information on growing 
conditions,
level of pest occurrence, or weather
conditions are input and the pro-
gram interprets the input to deter-
mine if a conclusion can be reached
or if more information is needed. At
the end of the conclusion, the farmer
can request "how" a conclusion was
reached and the logic flow and cal-
culations leading to the recommen-
dation are then displayed.
Currently, AAES researchers are
validating AU-Pnutat the Wiregrass
Substation in Headland. Also, ef-
fects of rotations, fungicide use pat-
terns for leafspot and white 
mold,
and variety susceptibility to fungal
diseases are being investigated to
refine knowledge on how these
inputs affect peanut yield, 
quality,
and pest management practices.
D.P. Davis, T.P. Mack, P.A. Backman,
and R, Rodriguez-Kabana
Classic Tank Mixes Can Cause Leaf Burn
Last
was lat
control
restrict
emerg
arose a
comm(
Resu
during
tion d
the tan
tempo
Disease cost May Be no sig
Cut for 
Southern 
Asana
720?,
Runners mixtur
Leafspot control 
alone may cost 
cant in
peanut growers over $50 per acre. sympt
Recent AAES tests indicate that slight i
fungicide cost 
may be reduced 
by combii
alternative management 
practices on 
Bravo
Southern Runner 
peanuts. 
the lev
Tests at the Wiregrass 
Substation 
combis
in Headland compared reduced rates Lanr
of Bravo@, longer 
intervals between 
Asana
Bravo applications, 
and the use of 
cides f
less expensive fungicides on Florun- sect pe
ner versus Southern 
Runner pea- 
on the
nuts. leafspc
By reducing the rate of Bravo from
1.5 pints (active ingredient) to 3/4
Effective Full season Spray Program On Yield
and Leafspot Severity of Southern Runner and
Treatment'
Op
h
Florunner
Bravo 0.55 lb. ........... 2,757
Bravo 1.1 lb ............... 2,868
Manzate 1.5 lb.
3  
2,649
Southern Runner
Bravo 0.55 lb. .............. 3,124
Bravo 1.1 Ib. .............. 3,179
Manzate 1.5 lb. ........... 3,143
rielo per acre
timum Harvest L
arvest 
delayed 
def
date 14 days
Lb. Lb.
2,666
2,672
2,114
3,344
3,106
2,837
1 All rates are in pounds active ingredient per ac
2 Defoliation rated 
prior to harvest.
3 Equals 2.0 pounds Manzate 200 BF.
-----
eafsp
oliati
Pct
44.
36.C
53.C
46.1
31.8
51.2
cre.
season Classic@ herl
beled for Florida beggar
in peanuts. Since the
s its use to 60-100 day!
ence, numerous que,
bout tank mixingitwitl
only used peanut pesti<
lts from a test cond
1989 at the Wiregrass Si
emonstrated that seve
k mix combinations did
rary peanut foliar buri
nificant yield reduction
XL@ formulation,
and Classic tank
e did show a signifi-
crease in foliar burn
oms, while it was
in all other tank mix
nations. Generally,
720 did not increase
el of damage in the
nation mixtures.
tate?, Orthene@, and
are labeled insecti-
or various foliar in-
stsof peanuts. Based
se results, Bravo, a
ot fungicide, could be
pint and delaying har-
vest 14 days, Florunner
yields dropped from
3,157 to 2,666 pounds per
acre, compared to 3,344
pounds per acre for
ot Southern Runner. By
on
2 
using Manzate@ instead
of Bravo for leafspot
control and delaying
harvest 14 days, Florun-
0 neryieldsdeclined from
2,649 to 2,114 pounds per
acre, compared 
to 2,837,
a decline from 3,143
pounds per acre for
Southern Runner, see
table.
Over the past 3 years,
Southern Runner has av-
safely mixed with Classic at their
recommended rates. Lannate or
Orthene also could be added to the
tank mixture if needed for foliar
insect control. Research indicates,
however, that foliage burn can be
expected when mixing Classic and
Bravo with Asana XL. Adding any
additional materials, such as crop
oils, sulfur, or foliage fertilizers, to
Classic-Bravo-insecticide spray
mixtures may increase the absorp-
tion of these pesticides and enhance
crop injury.
J.R. Weeks
ut Foliage Damage and Effect on Yield from
sticide Tank Mixes with Classic Herbicide
Pesticide mixture Leaf burn Yield/acre
Rating'
Classic + Larvin ............................. 0.2
Classic + Asana XL ....................... 0.8
Classic + Orthene .......................... 0.6
Classic + Lannate ............................. 0.6
Classic + Larvin + Bravo .................. 0.3
Classic + Asana XL + Bravo.......... 1.3
Classic + Orthene + Bravo ............. 0.6
Classic + Lannate + Bravo ............... 0.4
Untreated ........................................ 0.0
10 = no damage; 5 = total defoliation.
Lb.
3,280
3,385
3,381
3,505
3,482
3,428
3,469
3,182
3,312
eraged 65 percent less white mold
damage than Florunner in tests at
the AAES. Observations of the two
varieties indicate Southern Runner
is less susceptible to tomato spotted
wilt virus, but no differences were
detected in limb and pod rot, two
soilborne diseases that appear to be
increasinginfrequency in the South-
east.
Based on the AAES tests, it ap-
pears that Southern Runner can be
managed for peanut leafspot less in-
tensively and without significant
yield loss, and it is less susceptible to
white mold. It can be a good variety
to grow in fields with a history of
high white mold and leafspot pres-
sure.
J. C, Jacobi and P. A. Backman
Florunner Peanuts,
Three-year Average
I
Lime May Provide Peanut Calcium Needs
Calcium is still the most important
fertility input for peanut production
and seed quality in Alabama. Many
growers apply gypsum to supply
supplemental calcium, but recent
AAES research indicates that lime
may provide the calcium needs of
peanuts, if it is applied and man-
aged properly.
Yields decreased when lime was
placed below the pegging zone (top
3 inches of soil) with a moldboard
plow. When lime was placed and
remained in the pegging zone, yields
were equal to treatments in which
supplemental gypsum was applied
to peanuts. These tests also showed
that previously plowed down lime
can supply adequate calcium the
following year, if the field is plowed
again to bring the calcium back up to
the pegging zone.
Effect of calcium on seed quality is
also important since producers of
certified and foundation seed are
concerned with germination percent-
age of peanuts they produce. On-
farm tests have shown that germina-
tion is associated with seed calcium
content. These experiments have
also shown that the level of seed
calcium concentration for runner
type peanuts must be above 309 parts
per million (p.p.m.), whereas Vir-
ginia types require over 420 p.p.m.
to produce seed of maximum germi-
nation. These data also suggest that
maximum germination quality re-
quires higher soil test calcium than
is required for maximum yield.
J.F Adams and D.L. Hartzog
Computer Program Accurately Predicts
Leafspot Fungicide Needs
Peanut farmers who apply fungi-
cides on a 14-day programmed
schedule probably over-treat when
conditions are hot and dry, and
probably under-treat when condi-
tions are wet. Further, the new
leafspot tolerant vari-
ety Southern Runner
probably needs fewer
fungicide applications
to achieve 
maximum 
Percent il
yields than does the Flo- 90
runner variety. A
commercial company, 80
Neogen, is presently 70
developing 
a compu- 
60
terizedleafspotpredict-
ing weather 
station,
which by monitoring 40
weather and timing 
of 30 K
previous sprays can 20
provide a recommen- I
dation for the 
next 10
fungicide treatment. 
0
In 1989 AAES
research, the Neogen Envirocaster
was compared to a set of expert rules
for peanut leafspot treatment called
"AU-Pnuts." Both of these predic-
tive systems were compared to the
standard 14-day program.
The standard 14-day program
made seven applications of Bravo
720 during the 1989 peanut growing
season, while the Neogen and AU-
Pnuts systems each recommended
six applications. Disease control on
Florunner peanuts was best with the
AU-Pnuts program, with the 14-day
standard schedule second, and the
Neogen system last; however, all of
the schedules did a good job of dis-
ease control. The weakness of the
Neogen equipment was that it did
not utilize weather forecasts that
predicted long periods of rainfall
that occurred when tropical depres-
sions were in the vicinity.
In Southern Runner variety, AU-
Pnuts also was the top performing
program; Neogen's model again was
worse than the 14-day program.
Southern Runner yields showed
little response to these changes in
peanut leafspot control.
The data indicated that predictive
programs can be developed for
Southeastern peanuts that will al-
low for reductions in frequency of
pesticide applications. The applica-
tions made are more timely since
they are coordinated with infection
periods for the peanut leafspot fungi.
P. A. Backman, J. C. Jacobi,
and D. P. Davis
Comparison of leafspot predictive systems-Florunner
14-day program vs. Neogen and AU-Pnuts, 1989
% infection = leaves lost + leaves infected/total leaves
nfection
* 14-day
0 Enviro-L
d AU-Pnuts
None
Enviro
1
64 77 94 110 138
Days after planting
I
Nitrogen Fixation
Provides
Most of Peanut N
Requirement
Peanut plants are nitrogen-fixing
legumes that are able to obtain re-
quired nitrogen (N
2
) from the air.
The bacteria that 
carry out the N
2
fixation process live in nodules on
the peanut root. They also livein-
dependently in the soil and may
nodulate other legumes, such as
beggarweed, cowpea, and kudzu.
AAES research shows no shortage
of peanut rhizobia in soils of the
Wiregrass area, even after long
periods in pastures or woods.
Further research shows the effec-
tiveness of N2 fixation in providing
high yields of protein by peanuts.
From early pod development to
maturity, peanuts fix from 1.3 to 2.1
pounds of atmospheric nitrogen
per acre per day. Nearly all this
nitrogen goes into kernel develop-
ment. By harvest time, the crop has
obtained 67 to 82 percent of its total
nitrogen content from the atmos-
phere. Much of the soil-derived
portion of crop nitrogen is absorbed
EDITOR'S NOTE
Mention of company or trade names
does not indicate endorsement by the
Alabama Agricultural Experiment Station
or Auburn University of one brand over
another. Any mention of non-label uses or
applications in excess of labeled rates of
pesticides or other chemicals does not
constitute a recommendation. Such use in
research is simply part of the scientific in-
vestigation necessary to fully evaluate
materials and treatments.
Information contained herein is avail-
able to all persons without regard to race,
color, sex, or national origin.
April 1990 4M
Funds appropriated by the Alabama Legislature 
provide the major finan-
cial support for Alabama Agricultural Experiment Station research. Hatch
funds from the U.S. Government also represent an important funding
source. Since these funds are limited, many areas of research would go
unsupported, except for financial support from various granting agencies,
commodity groups, and other friends of the Experiment Station. Contribu-
tions of these supporters to the AAES program of research are acknowl-
edged with gratitude. Among these supporters of AAES research, the
following are recognized for their contributions to research on peanuts:
Alabama Farmers Federation
Alabama Peanut Producers Association
Dow Chemical Company
E.I. DuPont de Nemours and Company
ICI Americas, Incorporated
Mobay Corporation
Neogen Corporation
Pennwalt Corporation
Rhone Poulenc Ag Company
Uniroyal Chemical Company
USDA, Southern Integrated Pest Management Program
USDA, Federal Grant
Valent Corporation
in the pre-bloom 
stage before 
N
2
fixation becomes rapid.
The AAES studies 
indicate the N
2
fixation system can provide the ni-
trogen needed for maximum yield
Alabama Agricultural Experiment Station
Auburn University
Auburn University, Alabama 36849-0520
eanuts. Applying nitrogen fer-
er simply replaces a correspond-
amount that would be obtained
- the air and does not increase
1.
A.E. Hiltbold
NON-PROFIT ORG
POSTAGE & FEES PAID
PERMIT No 9
AUBURN, ALA,