As of Monday (5/8), we have turned hot and dry. In many fields we have walked across Central Alabama this week, moisture is lacking and stands are struggling to make. Some areas caught a rain yesterday, but storms were somewhat localized. Over the coming days, some fields may need to be irrigated up. As our agronomist Dr. Steve Brown says, farmers know their ground far better than we do, so you will know what you have and when it is time to make a call on a stand.
We have seen and heard a few reports of grasshoppers across
central Alabama. Nothing too bad but some requiring treatments. Remember that
the issue is more tied to the risk of stand loss and not leaf feeding. If
grasshoppers chew on the mainstem, that is often enough to lose the plant. We
don’t have any thresholds, so treatments are made based on the grower’s
acceptable risk. If stands are spotty, risk may be higher. With the number of
adult grasshoppers in the field, Dimilin alone will likely not be enough. In
our experience, acephate (0.67-0.75 lbs) does a good job on adults and the
added Dimilin (2 oz) provides good residual control of the immatures.
Moving to thrips, some things have changed from our last
update. Missing those couple of rain chances the past week has altered expected
pressure some in Central and South Alabama. Across these areas, now cotton
planted through the first week of May is at a higher risk. As previously
predicted, Cotton planted starting today (May 9) and later is at a much lower
risk overall. When we planted our thrips trials in Prattville on May 2, the
model rated the pressure around a “0.4,” which is pretty low. Today, the model
is predicting a “0.94.” This is a good reminder that the model can and does
change as weather predictions become a reality.
Bottom line: There is a good chance most of our (non-ThryvOn)
cotton planted before May 8th or so is going to need a foliar spray
to supplement at-plant insecticides. Keep watching the model and scouting for
thrips and injury. For the folks trying out ThryvOn, we do not expect to need
foliar sprays to supplement thrips control.
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.
