Keep Cotton Safe From Thrips Until Five Leaves
Dry weather patterns over the last few weeks have hampered our ability to get cotton to the five leaf stage, safe from thrips. Upcoming weather conditions look favorable to spur cotton growth. A few last things to keep in mind:
1) Our best foliar application, on average, is one that is made at the first true leaf stage. Your benefit for protecting cotton drops past this point. With warm moist weather ahead, any cotton at the three leaf stage or greater will likely reach the five leaf thrips-safe stage rapidly. These fields will likely receive little benefit from a foliar spray for thrips.
2) Avicta-Complete + Admire Pro (9.2 oz) is holding up well in most situations without an additional foliar overspray. I am even more convinced after this year that application method is critical and a few fields using this tactic have required a foliar overspray. It still pays to scout and cover yourself.
3) Sometimes it can be tricky to interpret what is going on behind a spray. My advice is to focus on the newest expanding leaf and to ignore old injury. What’s done is done. Also, be sure to look for live thrips in addition to looking at injury. This is the best way to tell how well your spray has worked. See this article and this article for advice on dealing with sprays that may or may not have worked.
4) Residual with our current foliar products for thrips is very little to non-existent. Colonizers can quickly reinvade a field after a spray if thrips are migrating.
5) We want to protect our cotton with sprays, but also want to preserve natural enemies. I was sent this photograph and had a chance to look at some seedlings this week where spider mites had moved in with a vengeance after a spray of acephate. Also sometimes our sprays will select Western flower thrips by eliminating all other species in the system. Western flower thrips also prey on spider mites. The seedings I looked at this week had a nice mixture of spider mites and thrips (probably Westerns). These thrips could chose from feeding on cotton and spider mites as it suited them.