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This is Jack Bacheler extension entomologist at NCSU with the Cotton Insect Update. Today is Wednesday, August 19.

Cotton in most places is moving quickly toward shutting down, although the crop is still mostly driven by its history of rainfall availability over the past 6 weeks, or so. Our crop ranges from being about a week away from cracked bolls to cotton that has first position white flowers 5-7 nodes down from the terminal. Good fall weather will bring an excellent crop to many.

As often happens at this time of year, bollworm moths and adult stink bugs levels can appear either scarce or plentiful depending on the field’s maturity level. At Rocky Mount yesterday, we evaluated a number of plots in both dry cutout fields and a field with a good moisture level. We didn’t observe the first moth in the dry field. In the lush cotton field, bollworm, tobacco budworm, soybean looper, and fall armyworm moths were commonly flushed as we walked from one area to the next. The level of moths was impressive, though not a threat to the drier cotton which had medium bolls all the way to the top.

Scouts and consultants can begin to prioritize their cotton fields into higher risk, later-maturing categories and focus their primary scouting efforts on those situations. Conventional and Bollgard cotton fields that are on the lush side and blooming well may be susceptible to significant bollworm damage and should receive the highest scouting priority. The same is true for all technologies with stink bugs.

On the other hand, if blooms and squares are becoming hard to find, those fields can be unattractive to stink bugs and bollworm moths. Additionally, bollworms have a hard time becoming established on medium-sized bolls, and stink bugs can not damage bolls that are more than 3.5 weeks old and have an approximate outside diameter of 1.25 inches. At this time of year, if three quarters or more of the bolls on a cotton plant are greater than the above size, an internal boll damage threshold of 30 to 50% on quarter-sized bolls is probably appropriate. In most situations, stink bugs do very little damage to cotton after the 7th week of bloom.

Fall armyworms are still a problem in some fields and made up approx. 1/4 of the bollworm/fall armyworm mix we found at Rocky Mount yesterday. Outside of WideStrike and Bollgard II, the insecticides with the most activity for falls are Coragen, Belt and Diamond, unfamiliar products to most cotton producers up this way. None of these products has any stink bug activity, however. In years past, bifenthrin (Capture, Brigade, and others) or Karate tank mixed with Larvin showed at fait to good fall armyworm activity, though Larvin has been hard to come by this season.

That’s it for this week. We’ll see you next week on August 18.