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This is Jack Bacheler, Extension Entomologist at NCSU with the Wednesday cotton insect update. This is Wednesday morning, July 29.

Stink bugs are far and away the main topic this week. We are in the middle of a combination of at least moderate levels of stink bugs, good moisture levels in much of the state and a susceptible boll damage state for much of our cotton crop. In all three of our stink bug threshold tests, the untreated checks are over the present threshold level of 10% internal damage to quarter-sized bolls. As was mentioned last week, stick to this 10% damage threshold levels until the beginning of the sixth of bloom. At that time, the threshold can be relaxed to 20 to 30%.

Examinations of these relatively small quarter-sized bolls for internal stained lint or warts must be done carefully as some of this damage may be subtle. If the correct 1-inch size is examined, most scouts will find probably it easier to squash and examine the bolls than to cut into all locks with a knife. Be sure to inspect the inside boll wall surfaces. More efficient scouting will likely result if all bolls are pulled, put into a nail pouch, and examined after exiting the cotton field. Transferring the bolls into zip lock bags and examining the bolls from a number of fields at the same time may also shorten the process. One final observation: when examining the bolls for internal damage, cut open the bolls with apparent external damage first. This will result in the opening of the bolls with the highest probability of internal damage first, and if the threshold has been met early in the boll sample, the remainder of the bolls will not need to be sampled if the producer or consultant is only seeking a spray vs. no-spray decision. On the other hand, the producer may be interested to find out if the threshold has only barely been reached or if the field is several times the threshold level of damage.

Based on calls and our own observations, a significant proportion of our cotton fields has probably reached or will soon reach the threshold level. Recent SE research has shown that a timely application based on threshold levels of damage during weeks 3-5 or 6 of blooming more that offsets the application cost. Also be aware the a grow may have one field that requires 2 stink bug treatments while another may not reach threshold, so scouting-based sprays are key.

Generally expect higher boll damage from stink bugs in areas of greater moisture.

As of this writing, the bollworm moth flight was underway throughout the state, though just getting underway in our northern counties. A Monday, July 27 count of more than 700 moths in a Scotland County light trap indicates that this flight is may be on the high side this season.

Because we are still getting reports of mostly brown stink bugs and with the flight underway, combinations of Bidrin plus pyrethroid tank mix are probably appropriate at this time.

With an apparently large corn earworm moth flight either underway or on the way, stink bug levels moderate to high side and soybean prices decent, this would not a good year to overlook the possibility of pod damage.

Please keep in touch with observations from your area. See you next on August 5.