Hi, this is Jack Bacheler again, Extension Entomologist at NCSU, with the Wednesday Cotton Insect Report.
Today is Wednesday, August 2.
Bollworms and Bt Cotton
As of today, the bollworm moth flight across the state is quite variable, with some light trap counts up and some down since this past Monday. However, the light trap in Robeson County was still going up and its Monday 2-day equivalent was over 1,000 moths. That's very high. Additionally, the flight there has now been underway for just over two weeks. Generally speaking, this is a moderate to big flight in many areas of the state. I know we mentioned it last week, but please refer to our Cotton Insect Corner web site for an easy glance at the flight's progress and status across the state. Just look under my name in the Entomology Dept. at NCSU and click on the picture of the black light trap. If you'll compare this year's flight with last years, you will see that this flight is about a week to 10 days earlier and much higher, so beware.
Although our limited conventional cotton has met the egg or worm threshold in most cotton fields in all areas of the state, decisions on Bollgard cotton have been more varied. In Bollgard or in WideStrike that has been already treated with either Bidrin or Orthene alone for stink bugs and or plant bugs, pay particular attention to the possibility of earlier and possibly higher bollworm establishment. Sound twice per week scouting at this time can head off these potentially high bollworm infestations. In Bollgard II, bollworms have a more difficult time becoming established, but significant economic damage from worms can occur in fields in which an OP was used for bugs within a week or less of a strong bollworm moth flight. Pyrethroid/Bidrin combinations probably make sense where bollworm and stink bug thresholds are being met, especially if brown stink bug are part of the mix. This very hot dry weather has resulted a quick production of bolls, high levels of stuck bloom tags in many cotton fields, and most eggs being deposited down in the plants, especially on pink and dried blooms. Watch for bollworms developing in these favored spots.
It seems like plant bugs have generally taken a back seat to stink bugs over much of the state, and damage by all bugs is extremely variable. This marks another year in which good scouting really pays. Last year's research both here and in Georgia suggested that weeks 3 through 6 of blooming were the cotton plant's most likely period for stink bug damage to bolls, so now would be a good time to respond quickly to threshold levels of bug damage to quarter-sized bolls.
We'll provide the next cotton insect update this coming Wednesday, August 9. See you then.