I was talking with Dr. Phillip Roberts yesterday and he was telling me that stinkbug populations may be higher than we have observed in recent years. Once plants begin setting bolls you need to begin monitoring for internal damage. Scout bolls approximately the diameter of a quarter. Bolls of this size are easy to squash between your thumb and forefinger and are the preferred size for stink bugs to feed. Bolls with callous growths (warts) and/or stained lint are considered damaged. Use the dynamic threshold based on the week of bloom to make treatment decisions. During the first week or ten days of bloom when bolls have not reached the size of a quarter, sample the largest bolls available. Stink bugs will feed on small bolls when 10-12 day old bolls (quarter-sized) are not present. Feeding on small bolls will cause them to be shed by the plant. Additionally, be on the lookout for whiteflies. Populations are steadily increasing with this hot dry weather. So far I have not seen or heard of a field at the threshold for whiteflies but be diligent with scouting.
Tips for Stinkbugs:
- If you have Silverleaf White Fly (SLWF) do not use Bidrin
- If you have SLWF and/or Spider Mites use Bifenthrin
- If Spider Mites are present do not use Acephate
- Make sure to treat only at the threshold levels
Threshold Levels:
- 2nd week of bloom – 20% internal boll damage
- 3rd week of bloom – 10-15% internal boll damage
- 4th week of bloom – 10-15% internal boll damage
- 5th week of bloom – 10-15% internal boll damage
- 6th week of bloom – 20% internal boll damage
- 7th week of bloom – 30% internal boll damage