Virginia Cotton: Focus Shifting to Bollworms; Control Varies by Variety

I got a chance to spend a little time north of highway 58 yesterday and while confirming that some corn earworm moths are present, the level was a bit lower and spottier compared to the flight I was seeing on Monday right along the NC/VA state line. 

  • Eggs in the more northern areas have been much harder to find compared to the southern and eastern areas.
  •  At this point, I am sure that the flight is earlier than normal just not consistently everywhere through the early part of this week.
  •  Stinkbug and Plant bugs continue the same pattern of fairly spotty and overall pretty low throughout the entire region. Stinkbug will likely build as corn dries.
  • I think we are reaching a consensus of focusing on the moth flight and egg laying on blooming cotton as the information we need to decide on spraying Widestrike 2 varieties like Phytogen 333. Besiege, Prevathon, or Belt are the best choices for these varities. Add pyrethroids to Prevathon or Belt for the stinkbugs and maybe a half rate for the Besiege. Intrepid Edge is effective but the residual time may be less and it really has not been tested in Virginia.
  • As we move to Widestrike 3 in new Phytogen varieties and TwinLink in new Stoneville, we can use the more traditional insect management strategy of dropping the stinkbug threshold to 10% damaged bolls during the third week of bloom and protecting with a high rate of a pyrethroid; something like 6.4 ounces of Bifenthrin or 3.2 ounces of Baythroid.
  • BollGuard 2, which is in all of the Deltapine, old Stoneville, NexGen, and DynaGrow varieties, is the primary question mark for me. 
  • Last year with tremendous moth pressure, it held up good enough to stick with a high rate of pyrethroid strategy without using products like Besiege. However, in North Carolina the pressure must have been even higher.
  • For these premium worm materials to work well, they need to be sprayed before the worms get established. So while it is a little bit of a dilemma, my approach for BollGuard 2 will be to plan on using the high rate of a pyrethroid only strategy unless I see extremely high moth or egg numbers.
  • Extension recommendations suggest using the premium worm products on bollguard when you have 25% to 30% eggs on bloom tags.

The insect situation is changing rapidly for our area. For about a week now we have gotten reports of an increasing bollworm moth flight, and the estimation has been that it will be as heavy as last years was. I’ve been in and out of hot spots but it has expanded in the last three days.

Herbicide Resistance Info

Plantbug surveys from the Tidewater research station have reported significant increase in insect numbers this week and stinkbugs. Fields that are actually being scouted on a field by field basis are indicating some fields need spraying and some do least yesterday (7/26).

None of this is a surprise and we now find ourselves at the ‘pulling the trigger stage’ right as we are expecting a nice rain event to remain in the area through Saturday. It is a good problem to have. I think many of the nice cotton crops have occurred the same years we have trouble getting the insects sprayed.

As you set your priorities, I would focus on the older cotton which has passed the 3rd week of bloom and is blooming high in the plant. Widestrike 2 varieties will need different insecticide than Widestrike 3 and BollGuard 2 technology is somewhere in the middle.



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