Bollworm eggs are in cotton fields—what is the best approach for treatments?

In cotton, we are beginning to find corn earworm (=bollworm) eggs in fields. This fits what we would expect given the increase in moth activity. This is a little earlier than normal. Over the past several years, we have seen egg lay start during the first week of August. I suggest that any sprays from this time forward should be directed to bollworm and stink bug. In the past, we have been able to get good control of bollworms in BG2 or Widestrike cotton varieties with a single application of a pyrethroid at the highest labeled rate for that product. Pyrethroids are also picking up most of any stink bugs that could be present. We time the application to coincide with what used to be the second spray in the old (pre-BG cotton days) egg threshold two-spray system (first app at egg threshold, the second in 5-7 days). A treatment 5-7 days after the old egg threshold is designed to target any worms that have escaped the Bt toxins, but would still be small enough to kill with the pyrethroids before doing any significant boll damage. Up until now (at least based on data up to 2011), the single high rate pyrethroid treatment has remained effective in cotton because (in my opinion), if timed correctly they are directed to a small number of small larvae—easier to kill and fewer to kill. We have field trials in place to continue monitoring this.

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