Cotton planting has started across the state at some level.
Depending on location, moisture (too much or too little) has been a limiting
factor slowing down widespread planting. At this point, I would start as soon
as soil moisture allows. With that in mind, weather conditions significantly
impact thrips flights in cotton. The thrips model was down for awhile but is
back up and running now. Thus far, it is pretty easy to summarize the risk of
thrips injury across the state. For all models, we selected an anticipated
planting date of May 1.
Disclaimers: This model reads past, current and predicted
weather to line up how cotton growth/development and thrips movement/development
interact. Risk is subject to change as weather changes. We recommend running
the model before planting and a couple of days after planting too to ensure
things didn’t change. https://products.climate.ncsu.edu/ag/cottontip/
South Alabama:
We ran the model in Henry and Escambia counties and got
similar results. For both, the expected thrips pressure is LOW for cotton
planted in May. Cotton planted before today (April 28) is at a MODERATE risk,
but overall most of the cotton planted from now on is not expected to be at much
risk of thrips injury.
Central Alabama:
We ran the model in Elmore, Autauga and Dallas counties with
similar results. Cotton planted through about May 14th is at LOW risk
of thrips injury.
North Alabama:
We ran the model in Limestone, Cherokee, Pickens and
Talladega counties.
Limestone Co.: Cotton planted beginning around May 1 is at
HIGH risk of thrips injury. The elevated risk continues until at least May 20.
Cherokee Co.: Cotton planted around May 5 is at HIGH risk of
thrips injury. This risk again remains elevated until at least May 20.
Pickens Co.: Cotton planted through at least May 20 is
expected to be at LOW risk of thrips injury.
Talladega Co.: Cotton planted before about May 12 is
expected to be at LOW to MODERATE risk of thrips injury. As planting dates push
into May 20, cotton is expected to be at LOW risk.
How does this impact thrips management decisions?
Cotton at LOW risk will likely only need seed treatments this year. I would strongly consider not spending money on additional in-furrow insecticides for cotton at LOW risk. However, make sure cotton seed has a full rate of imidacloprid seed treatment. Each seed brand has its own code or brand for what insecticides and fungicides the seed was treated with. The lowest rate recommended for thrips control is 0.375 mg/seed (12.6 oz per 100 lb of seed) of imidacloprid.
Cotton at MODERATE risk may or may not benefit from an
additional in-furrow insecticide. I would again recommend considering leaving
out the in-furrow and evaluating the seed treatment and make foliar sprays if
necessary.
Cotton at HIGH risk will likely need an insecticide to
supplement seed treatments. If in-furrow applications are possible, there are
several options:
1.
AgLogic (3.5 lbs/A) provides excellent control
of thrips
2.
Imidacloprid (9.2 oz/A) provides very good
control of thrips
3.
Acephate (1 lb/A) provides sporadic control. In
my experience, acephate does not perform as well in wet soil conditions
If in-furrow applications are not possible, I would be
prepared to make a foliar application around the 1 true leaf stage. Again, we
have several good options for control:
1.
Intrepid Edge (3 oz/A) /Hemi (1.5 oz/A). Intrepid
Edge is a pre-mix of spinetoram and methoxyfenozide while Hemi (1.5 oz/A) is
spinetoram alone. Both products should provide comparable control of thrips and
are safe on beneficials (low risk to flare spider mites).
2.
Acephate (3 oz/A) is an effective and
relatively inexpensive option, however it has the potential to flare secondary
pests such as spider mites and is the least rainfast of the recommended options
available.
3.
Bidrin (3.2 oz/A) is another option that is
effective and less likely to flare spider mites and is more rainfast than
acephate, however it is more likely to cause crop injury when tank-mixed with
herbicides.
A reminder that pyrethroids are not effective and
should not be used to control thrips.
ThryvOn cotton provides excellent control of thrips. To
date, we have not observed thrips damage in cotton that justified an in-furrow
or foliar application.
As always, if we can ever be of any help, or if you would
like to provide input on the situation in your area, please don’t hesitate to
reach out to your local Extension Agent or myself (Scott Graham: 662-809-3368) and Ron Smith (334-332-9501). For more
information on thresholds and insecticide recommendations, visit the Alabama
Cotton IPM Guide (IPM-0415). To stay up-to-date on the Alabama cotton insect situation,
subscribe to the Alabama Cotton Shorts Newsletter,
Alabama Crops Report Newsletter and Podcast,
and the Syngenta Pest Patrol Hotline.
