July 27, 2001 http://commodities.caes.uga.edu/fieldcrops/cotton/
Crop Condition Manage Stink Bugs Black Rot Revisited and Updated: What’s left for young
agronomists and pathologists Cotton Producers Can Expect Sizable POP This Fall |
Crop Condition. (Brown) Prospects for the 1.6 million-acre 2001 Georgia cotton crop are significantly better than that of previous seasons. Rains in June through early July brought good vegetative growth and a respectable push into bloom. Many parts of the state went without rain
from the 4th of July until this current
week. Crop growth stage ranges from a
few acres in the early square stage to substantial acreage just past peak bloom
approaching cutout. Scattered acres
have been abandoned because of severe, persisting drought. Water is critical to carry the fruit load to
maturity.
Georgia Agricultural Statistics
estimates that as of July 23, 65 percent of the crop is setting bolls. Crop conditions on that date were 1
percent–Very Poor, 7 percent–Poor, 29 percent–Fair, 49 percent–Good, and 14
percent–Excellent.
Over the past weeks we’ve seen
numerous fields with poor color. Pale,
yellow foliage has been attributed to 1) tardy N sidedress applications, 2) N leaching and/or waterlogged roots
caused by excess rain, 3) inadequate K rates,
4) imbalances between N and S.
There are a few situations in which it is hard to explain what happened,
why the field has yellowed.
Now is also the crucial period for
insect control. Scouts and growers
should sharpen their efforts on stink bugs and corn earworms. When needed, timely intervention could return
50 to 200 lbs of lint for a treatment that costs less than $10/A.
Manage Stink Bugs. (Roberts) Stink bugs are a primary pest of Georgia
cotton and must be effectively managed
to maximize profit. Management may not
mean spraying every field for stink bugs, but it does mean scouting each field
and using insecticides when needed.
Scouting for stink bugs should be initiated when cotton begins setting
bolls. Populations may be estimated
using an internal boll damage assessment (the preferred method) and/or a drop
cloth count. Fields which have not been
treated with a broad spectrum insecticide such as a pyrethroid during the past
two weeks are at highest risk for stink bug damage. To date, a large percentage of fields in Georgia are in this
category.
Stink bugs damage cotton with
their piercing/sucking mouthparts by injecting digestive enzymes and feeding on
developing seeds within bolls. In
addition to physical damage to bolls, this process allows the entry of rot
organisms that also reduce yield and quality.
Bolls which have been damaged by stink bugs are easily recognized by
looking for internal symptoms of injury.
Internal symptoms include stained lint and/or warty callous growths on
the inner surface of the boll wall.
Previous research has shown that these callous growths appear within 48
hours after the bug feeds on a boll. In
addition to stink bugs, other bugs such as tarnished plant bug and leaf-footed
bugs may also feed on developing bolls and cause damage which is indistinguishable
from that caused by stink bugs.
During 1999 and 2000, Drs. Gary
Herzog and Jeremy Greene coordinated research addressing economic thresholds
for stink bugs. Five trials were
conducted in Bt cotton fields. Treatments
included Bidrin (8 ozs/A) sprays at various threshold levels (10, 20, and 30
percent internal boll damage, 1 stink bug per 6 row feet, and an
untreated). Plots were scouted weekly
and each treatment was treated on an as needed basis. Highest yields (+109 lbs lint/A) were obtained in the 20 percent
internal damage threshold plots which required two applications of Bidrin. Similar yields were also produced using the
10 percent damage threshold but with the expense of two additional Bidrin
Sprays. The 30 percent damage threshold
and 1 stink bug per 6 row feet treatments required one or fewer Bidrin sprays
and did not result in significant yield increases compared with the
untreated. Because plants were
exceedingly tall at several sites, bugs were difficult to detect in the
elevated canopies using the drop cloth technique. This could have resulted in densities exceeding threshold without
detection, fewer insecticide applications, more boll damage, and reduced
yields. Based on these studies,
managing stink bugs using the 20 percent internal boll damage threshold
returned a net gain of $48.48 to the grower.
Net gain was calculated with yield gain at $0.60 per lb of lint minus
$8.31 per Bidrin acre application ($5.31 for insecticide plus $3.00 application
costs). Two on farm trials were also
conducted in Irwin County. Treatments
included a pyrethroid at the 20 percent internal damage threshold and an
untreated. One application was needed
at each location and yields were increased 122 and 56 lbs lint/A when stink
bugs were managed.
Recommended insecticides for stink
bugs include several pyrethroids and the organophosphates Bidrin and methyl
parathion. Vydate was also recently
labeled for control of green and southern green stink bugs. Based on additional research by Drs. Herzog
and Greene, bolls are most susceptible to stink bug injury until 20 to 25 days
after white bloom.
Black Rot Revisited and
Updated: What’s left for young agronomists and pathologists? (Kemerait, Jost, Harris, and Gary Gascho) It has been about five years since a malady
of cotton, later to become known as “black root”, was recognized and initially
studied in Georgia by Dr. Rich Baird and county agents such as Forrest Connelly
and James Clark. Black root was
described as a new “disease”, although the causal agent was unknown. The condition was reported to be widespread
in 30 counties in the state. As many
are aware, symptoms of black root included a superficial darkening of the
roots, gall formations that could be cracked and/or corky in texture, severe
boll abortion, and foliage with symptoms that have been referred to as
“windowpaning” and like chemical injury.
Since that time, and after great effort by Dr. Baird, no pathogen has
ever been successfully linked to black root and the malady is now considered to
be most likely the result of environmental conditions.
The recent studies of black root have been conducted by Dr.
Gary Gascho, a soil scientist located in Tifton. It is now generally recognized that most true cases of black root
are confined to poorly drained flatwood soils, especially in areas such as
Appling, Jeff Davis, and Berrien Counties.
However, at least some black root is also appearing in other poorly
drained sites, such as in Cook County.
It now seems that the earlier description of black root as “widespread
in 30 counties” was premature. There
has not been a confirmed case from well-drained, coastal plain soils, though
the general symptoms of black root make it easy to confuse black root with
other stress related problems of cotton.
For example, plant samples have been submitted in the past year from
Houston and Bleckley Counties with some symptoms that resembled black root, but
turned out to be unrelated.
Dr. Gascho’s work has focused on
chloride toxicity as a possible cause of the black root problem. A similar problem and damage occurs in
certain susceptible cultivars of soybean that translocate chloride ions from
the roots to the foliage.
(Non-susceptible soybean cultivars retain chloride in their roots.) In his research, Dr. Gascho has been able to
produce similar symptoms on cotton grown in the greenhouse in the presence of
high chloride levels. He has also
conducted field research to determine if soil amendments such as poultry
litter, gypsum, or low chlorine fertilizers might help to reduce the severity
of the problem. Poultry litter, which
is an organic source of nitrogen, seems to be a partially effective means to
minimize the severity of black root in fields where it is a problem. Poultry litter contains many nutrients and
non-nutrients, which makes the reason for the positive growth, development, and
yield responses in cotton difficult to discern. The current thought is that black root of cotton may be the
result of interactions between chloride and nitrogen that occur in poorly
drained fields and that the dark symptoms on the root may actually be from
ammonia burn. As of now, the idea of
the ammonia burn is unproven; however, observations by Dr. Gascho in 2001 have
implicated nitrogen nutrition as a factor.
Because of the symptoms and yield
losses associated with black root, plant pathologists and agronomists will
continue to play a role in the study of black root, both evaluating it in the
field and diagnosing it in the disease clinic.
Although no pathogen has ever been successfully linked to this
condition, the ultimate cause of black root remains elusive. Therefore, pathologists will remain involved
in the study of this condition and contribute expertise that will lead to a
better understanding of the issue.
Cotton Producers Can Expect
Sizable POP This Fall. (Shurley) The 2001 US crop is likely to be 19 to 20
million bales. USDA’s July forecast was
19.2 million bales. While there are
many unknowns, it will be difficult to pull out of the current weakness in the
market. One factor that producers have
relied on in recent years to augment low cash prices has been the Loan
Deficiency Payment (LDP) or POP.
The POP is derived from the
A-Index or “world price” of cotton as shown in the table below. When the A-Index goes down, the AWP declines
and producers will be eligible for a POP payment if the AWP is less than the
loan rate.
This past year, the A-Index was
strong during harvest time and the POP reached a maximum of about 4 cents. After harvest, the “A” begin to decline as
did US prices as world production was larger than expected and demand began to
slip. This resulted in producers
getting a large marketing loan gain if cotton was stored in CCC loan or a POP
of 15-20 cents or more if producers declined the POP at harvest and held the
cotton in regular storage.
One thing that has happened in the
past 2 years is that the A-NY relationship has gone from what typically was a minus
3 to 5 cents to a plus 3 cents or more.
This is because US cotton prices have weakened more relative to foreign
prices. The result is that even though
US prices are low, we’re not likely to get as much POP to help us out as we
have in the past.
Example of US and World Price
Relationship and Calculation of POP Payment
Futures and Cash |
|
A-Index - NY Relationship |
AWP and LDP (POP) |
|
Futures (Dec) 7/25/01 |
40.90 |
+3.25 |
A-Index 7/26/01 |
44.15 |
Basis 7/25/01 |
-4.15 |
|
Adjustment |
-13.64 |
Current Cash Position |
36.75 |
|
AWP |
30.51 |
|
|
|
POP (51.92-AWP) |
21.41 |
Total Price |
|
58.16 |
|
|
With world production and stocks
increasing, the A-Index is currently at about 44 cents and may go even
lower. Currently, if the “A” stays were
it is, we’re looking at a 21 cent POP this fall. With futures prices in the low 40's, this translates into
something in the upper 30's for a cash market.
So, if the A-NY relationship stays the same as it is now, producers are
looking at a total of around 60 cents this fall one way or the other.
It is likely this year will be the
opposite of last. The “A” will probably
increase over the winter months. This
means, the temptation will be to take the large POP this fall. Then, the MAJOR decision becomes what to do
with the cotton. According to the
latest data, only 4% of the Georgia crop and 5% US is contracted. Profitable opportunities have been almost non-existent.
Estimated Acreage Equivalent of
Cotton Forward Contracted as of July 1
|
2000 Crop |
2001 Crop |
Georgia |
22% |
4% |
Southeast |
19% |
6% |
US |
9% |
5% |
Source: USDA-AMS
The alternatives available include
POP and sell, POP and store, POP and place “on-call” or price later, POP and
sell plus Call Option, or place in Loan.
At 21 cents per pound, the $75,000 limit on LDP’s (POP’s) and marketing
loan gains will be reached at approximately 715 bales.
With cotton prices so low, it is
natural for producers to consider spending as little as possible or nothing on
late season inputs. Every input should
always be evaluated in good years as well as bad. But cost savings must be weighed against potential yield and
quality losses and remember to base this decision on 58 to 60-cent cotton and
not 40.
Prepared by:
Steven M. Brown, Extension
Agronomist-Cotton
Philip H. Jost, Extension
Agronomist-Cotton & Ag Crops
Glendon H. Harris, Jr., Extension Agronomist-Soils & Fertilizer
Bob Kemerait, Extension Plant
Pathologist
Phillip Roberts, Extension Entomologist-Cotton
Don Shurley, Extension Economist
Gary Gascho, Research Agronomist
Tiftarea UGA Cotton Research Tour
Wednesday, August 15, 2001
9:00 Convene at
the RDC Pavilion
9:15 Depart for
RDC Pivot
Narrow
Row versus Wide Row (Bader)
Foliar
Fertilizer / Hormone Products (Harris, Bednarz)
Skip
Row Patterns (Jost, Brown)
Effects
of Extreme Plant Bug Populations (Roberts, Bednarz)
Thrips
Control with Seed Treatments and In-Furrow Products (Roberts)
10:00 Depart for
Gibbs Farm
Enhanced
Glyphosate Tolerance Events (May)
Official
Variety Trial (May)
Breeding
Nursery (May)
Nematode
Control (Davis, Bader)
Irrigation
Studies (Bednarz)
N
Studies (Gascho)
12:15 Depart for
Ponder Farm
Lunch
(provided on site)
Population
Densities (Bednarz)
Flowering
Habits of Early versus Full Season Varieties (Bednarz)
Weed
Control with Enhanced Glyphosate and Liberty Cotton (May)
Cadre
Carryover (Bednarz, Prostko)
Messenger
(Bednarz, Brown)
Growth
Regulation in Narrow Row Cotton (Bader)
Weed
Management
2:45 Depart for
Lang Farm
Nematode
Control (May, Davis)
Thrips
Control / Planting Date (Roberts)
Residual
Litter Rates (Gascho)
Transgenic
Cotton / Technology Systems Trial (May)
Conservation
Tillage / Rotation (Lee)
3:30 Return to
RDC
The tour is intended for growers,
county agents, and agribusiness persons.
Participants are encouraged to gather in as few vehicles as possible to
expedite travel from site to site. Total
number will be limited to the first 150.
For registration, please contact the RDC Conference Office at 229 /
386-3416 no later than Friday, August 10.