Good news, bad news. The good news – I’ve only had a few calls about high infestation levels of bollworm (= corn earworm) in soybean. Most of these reports have been in late maturing soybean fields in or near the Mississippi River Bottoms. Bollworm infestation in cotton appear to be light to moderate. However, a number of people are seeing at least a few worms sneak past Bt cotton technologies. Also on the positive side, I’ve had feedback that applications of Prevathon or Besiege (mostly on the original WideStrike technology) appear to be working well, and I received similar feedback on applications of pyrethroid insecticides when mixed with acephate (mostly on Bollgard 2).
The bad news – Tennessee is surrounded by reliable reports that Bt cotton technologies are not providing satisfactory control of bollworms in some fields, and there are also reports of poor control with insecticide applications in cotton. A combination of high pressure, pyrethroid resistance, and bollworm resistance to Bt toxins is contributing to the problem.
It is very possible that late maturing cotton under moderate to high pressure will require an insecticide application to control bollworm. This is almost a given on WideStrike. It is critically important to closely scout susceptible cotton fields for bollworm infestations and make the appropriate insecticide application as needed. This does not mean spray every field. Our earliest cotton is already past the point of concern, having accumulated > 350 DD60s past NAWF5.
Below are a few thoughts for your consideration:
Source: University of Tennessee, By: Scott Stewart
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