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This is Jack Bacheler again, Extension Entomologist at North Carolina State University with the weekly cotton and soybean update. Today is Wednesday, August 8.
Our variable insect levels and relative pest rankings continue on cotton. Additional untreated cotton fields reached threshold for stink bugs this past week, with probably more sprayed than unsprayed fields in North Carolina now. Several consultants are reporting stink bug damage levels in the single digits. For some producers, this week marks the end of the protective weeks 3 to 5 of the bloom period for stink bug damage. Thresholds 20, 30 and 50% internal boll damage, respectively, are recommended for 6 weeks through 8 of the bloom period. This is a stage of cotton when bolls become less vulnerable to stink bug damage. Brown stink bugs still predominate in most areas.
Low bollworm moth counts from light traps continue to amaze me, as a number of traps are in the single digits to only the teens for two-day checks at a time in early to mid-August when these same traps were often in the low hundreds in other years. Hopefully, this is translating into very little bollworm establishment so far in 2012, although pockets of high moth activity always seem to materialize.
It appears that good rainfall patterns helped with what was shaping up to be a higher than average mite year for us. Fortunately, we spray only about 5% of our cotton acreage for spider mites most years. Because of the confirmed aphid resistance to chloronicotinoids a couple of weeks ago and some additional control issues were probably related to resistance, we’re fortunate to be in an upper Southeast cotton production region were aphid outbreaks are often controlled by aphid mummies and the fungus.
Kudzu bugs generally have not become quite the terror that we expected at this point. Knock on wood. Although more soybean fields reached the 15 nymph per 15 sweep threshold this past week, widespread treatment has not been needed. We are now wondering about the intensity of this year’s major kudzu bug flights, but will also keep our fingers crossed for the next 2-3 weeks. Sweeping is probably more effective if done between approximately 11 am and 3 or 4 pm when the kudzu bug nymphs are more likely to be higher in the plants and within sweeping range.
Unfortunately, we are not at the insect safe point yet for cotton and soybeans, but with continued warm weather, most of our crop should progress nicely toward cutout in areas of good moisture.
The next insect update will be provided this coming Wednesday, August 15. See you then.