Crunch Time For Insect Management In Cotton

By Scott Stewart

The next 2-3 weeks is traditionally the most critical window for managing insect pests in cotton. We are setting the bolls that will make or break our crop, and it is harder to recover from significant boll injury than it is to compensate for the loss of early season. This mid-flowering window is the time when immature plant bugs, stink bug, and bollworm infestations may all coincide. Moth traps are beginning to show the onset of our traditional bollworm flight.

Stink bugs, although a significant pest, are relatively easy to control. The almost universal use of Bt cotton provides considerable (but not perfect) protection from caterpillar pests. Thus, most of our insecticide decisions will be centered around controlling tarnished plant bugs. During bloom, the tier one products for control of tarnished plant bug include Acephate/Orthene(0.67 – 1.0 lb/acre), Bidrin (6-8 oz/acre), and Transform (1.5 oz/acre). There are other options, but these products typically provide the most consistent control. I often suggest starting with these products and adding in a tank mix partner according to what other pests are in the field

  (see   below).

•  Pyrethoid insecticides as a tank mix partner: Pyrethroids add control of bollworms that may be present and improves the limited control of stink bugs provided by Transform. Most pyrethroid insecticides such as Baythroid, Declare, Mustang Max and Karate provide good control of green stink bugs. The bifenthrin products such as Brigade, Discipline, Tundra and Sniper will be better at controlling brown stink bugs. Although pyrethroid insecticides are a VERY poor choice to apply alone for tarnished plant bug, they often add a little extra kick when mixed with other insecticides used for plant bug control. Anyone that talks to me regularly knows I really like tank mixing Orthene or Bidrin with a pyrethroid insecticide during late July and early August. Similarly, you could do the same with Transform. Brigade XPII is a premix that fits well at a rate of 10-12 oz/acre.
• Diamond (4-6 oz/acre) as a tank mix partner: I’m a little less inclined to recommend mixing in Diamond as we get further into boll development.  It doesn’t add a whole lot to control of bollworm and stink bugs. It still has use, particularly when the primary target is plant bugs. Also, if mixed with a good dose of Acephate or Bidrin, the weakness on stink bugs doesn’t really matter.