Agricultural Extension Service
The University of Tennessee
IPM NEWSLETTER
Update for Field Crops and Their Pests
No. 20
605
Airways
Boulevard
Jackson, TN
38301-3201
September 19, 2003
Past Newsletters and other information can be found at UTcrops.com
CONTENTS (links):
Cotton Crop Update
Soybean Update
Cotton
Crop Update (Chism Craig, Assistant Professor)
The Tennessee Ag-Statistics service reports that 36% of the crop has an open boll
compared to 70% last year and the five year average of 80%. I would guess that about
1% of the acreage has been picked but most early defoliated cotton will get harvested
sometime next week barring any weather delays. The rapid boll opening has slowed
somewhat in the last few days as low temperatures have dipped into the mid-50’s.
However, the 7 day forecast is favorable and I don’t think it will get as cool as once
suspected. It is becoming more evident in late cotton which producers were aggressive
with mepiquat treatments and which were not. I’m still holding my breath that this late
crop will fully develop and open. Defoliation increases each day and by next week a
good portion of the crop will get a treatment. On well cut-out cotton, Def or Aim +
Ethephon has been very effective and in all demo plots this year, combinations of Finish
or CottonQuik tankmixed with Aim or Def have looked extremely good. Boll opening
has been rapid and in some cases picking could have started in 7-8 days. Producers
continue to have trouble with green areas in the field and some are applying a follow up
shot to clean up misses. More and more producers are asking about two shot programs
and a few have applied low rates of Def and ethephon to condition the greener cotton.
Defoliation has been relatively simple to date and will get more interesting once
conditions worsen. Here are a few of the treatments that have been working in our plots.
Please take into considerations that other treatments are available and conditions have
been excellent for defoliation.
One shot:
8 oz Def + 24 oz Ethephon (Prep, Superboll, Ethephon 6)
0.75 oz Aim + 24 oz Ethephon (Aim rates can be adjusted based on
temperature….increased as temperatures decrease)
21 oz Finish 6 Pro + 5 oz Def
21 oz Finish 6 Pro + 0.5 oz Aim
56 oz CottonQuik + 5 oz Def
56 oz CottonQuik + 0.5 oz Aim
8 oz Finish 6 Pro + 20 oz Ethephon + 5 oz Def
12 oz Finish 6 Pro + 16 oz Ethephon + 5 oz Def
(Aim can be substituted for Def especially if weed desiccation is desired)
21 oz Finish + 4 oz Ginstar
56 oz CottonQuik + 4 oz Ginstar
(Higher rates of Ginstar may stick leaves when temperatures are above 85oF and
rates may need to be adjusted)
Addition of a regrowth material like Dropp, Freefall or Ginstar is advised when
conditions favor regrowth (warm, moist conditions, high N application late in the season,
or when delays in picking are expected)
Two Shot: (1st Shot)
4 oz Def + 10 oz Ethephon
0.5 oz Aim + 0.25% NIS
0.1# Dropp/Freefall + 0.5% NIS
4 oz Harvade + 0.5% NIS
10 oz Leaflesss
12.8 oz CottonQuik + 4 oz Def
5.33 oz Finish 6 Pro + 4 oz Def
4 oz Ginstar
Follow-ups:
8 oz Def + 24-32 oz Ethephon
1 oz Aim + 24-32 oz Ethephon
56-64 oz CottonQuik
21-24 oz Finish 6 Pro
10 oz Leafless
32 oz Ethephon
Many follow-up treatments will work well. However, the follow-up should contain
adequate defoliant to finish the job but most importantly, adequate boll opener to
stimulate boll opening.
One thing to remember about two shot applications is that you should make up your mind
about using two shots before treatment not after unsatisfactory results from the first
application. The goal of the first shot is not to completely defoliate rather set the crop up
for the second shot. The first shot should not be too hot to stick leaves; it should open the
canopy to allow better penetration of the defoliant and increase boll coverage of the boll
opener. As we get into October and temperatures drop, we will need to increase the rates
of our herbicidal defoliants like Def, Aim and Ginstar in both one and two shot
applications. You may notice that my ethephon rates are equivalent to at least 24 oz per
acre. Ethephon prices are fairly low and I strongly recommend adding as much as you
can afford. I really believe that addition of ethephon is cheaper than scrapping. Addition
of Crop Oil Concentrate instead of NIS may be useful when temperatures fall or when
leaves are extremely waxy from drought stress. Keep in mind that Dropp/Freefall
activity significantly declines when temperatures fall below 65oF and that activity is
fairly slow under good conditions.
One final note. My first plots picked here on the research station have averaged well
over two bales and yields in our Shelby County demo plot appeared to be excellent as
well. I hope this trend will continue as more pickers get to the field.
Haywood County Defoliation Demonstration
Thursday September 25, 8:00 a.m.
The plot is located at the Littlejohn Farm on Tibbs Road. Directions from Brownsville:
turn on Hwy 54N &immediately turn left on Thomas St., at the 4-way, turn right on
McLemore (turns into Tibbs Road). Field is ~2.5 miles on the right
Crockett County Defoliation Demonstration
Friday September 26, 8:00 a.m.
The plot is located north of Alamo on Highway 54 at Pete Tinsley Road (just past
Tennessee Tractor).
For more information contact the Haywood or Crockett county extension office.
Location
Ames
Brownsville
Covington
Dyersburg
Jackson
Memphis
Milan
DD60 Accumulation
4/13--9/14
5/4--9/14 5/30--9/14
2205
2083
1814
2384
2244
1947
2110
1986
1737
2235
2102
1818
2166
2037
1785
2317
2173
1883
2072
1946
1705
Location
Ames
Brownsville
Covington
Dyersburg
Jackson
Memphis
Milan
7/21--9/14
1027
1107
970
1001
1006
1061
958
DD60's after NAWF 5
7/27--9/14
8/4--9/14
909
776
982
831
855
722
881
745
888
754
936
797
847
714
Weekly Accumulation
99
106
88
87
95
104
85
8/10--9/14
648
690
596
618
633
663
596
Soybean
Crop Update
Angela Thompson, Extension Corn and Soybean Specialist
Russ Patrick, Extension Soybean Entomologist
The soybean aphid has been found in two Tennessee counties. Producers and extension
agents are being encouraged to examine fields in middle Tennessee, particularly those
bordering Kentucky. In Rutherford County, a few aphids were found in the Eagleville
community by Bud Twitty and Mike Fouts with Pioneer Seed Company. Heavier
populations were found in Williamson County (Franklin area) where aphids at 50 or more
per leaf were present in a few fields. Aphid specimens were confirmed by Russ Patrick
and Scott Stewart, State Extension Entomologists, at the West Tennessee Experiment
Station in Jackson.
Soybean aphids are a persistent pest in many soybean producing areas of the upper
Midwest, but have not been found further south than Kentucky until now. Tennessee has
not established a treatment threshold yet, but other states are using populations of 200 to
250 aphids per plant at the R2-R4 stage as the optimal time to apply an insecticide. A
pyrethroid insecticide labeled for soybeans can be effective, as well as Lorsban or
Furadan. In many states that routinely treat for this pest, growers are cautioned to spray
only when necessary and let natural enemies help manage aphid populations.
DISCLAIMER STATEMENT
Pesticides recommended herein were registered for the prescribed uses when this publication was printed. Should
registration be canceled, the University of Tennessee will immediately discontinue its recommendation of the
pesticide. Use of trade or brand names in this publication is for clarity and information; it does not imply approval
of the product to the exclusion of others that may be of similar, suitable composition, nor does it guarantee or
warrant the standard of the product.
The Agricultural Extension Service offers its programs to all eligible persons regardless of race, color, national origin, sex religion,
disability or veteran status and is an Equal Opportunity Employer. COOPERATIVE EXTENSION WORK IN AGRICULTURE
AND HOME ECONOMICS.
The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating in
furtherance of Acts of May 8 and June 30, 1914. Agricultural Extension Service, Charles L. Norman, Dean.
Scott D. Stewart (editor)
Extension Cotton IPM Specialist