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This is Jack Bacheler, extension entomologist at NCSU with the cotton and soybean update. Today is Wednesday, June 27.
As always, our unfolding insect pest year seems influenced by weather patterns. On the plus side, most areas of the state now have adequate moisture levels, at least until later this week and weekend when very hot sunny weather will predominate. Hopefully, the generally good moisture levels to this point have helped hold off slowly building mite populations. We have had some fields treated for a combination of square retention counts approaching or less than 80% along with adult plants bugs. Producers should be advised to hold off on treatment until both square retention drops to the range of 80% or less and 8 or more plant bugs per 100 sweeps are found. At this time of year in NC, a high proportion of our plant bugs should be adults. Once cotton is approximately a week into blooming, the use of a black or dark-colored ground cloth is advised and the small bright green plant bug nymphs may become more prevalent. If treatment is needed, the use of chloronicotinoids such as Centric, Admire Pro and Belay should be restricted to cases of exceeding the threshold by perhaps 1.5-fold. This class of insecticides may help lessen the need for subsequent sprays for cotton aphids and spider mites. The bigger guns such as Bidrin, Brigadier, acephate Transform and Endigo should be used in cases of higher plant bug levels and/or subsequent sprays. The use of these latter materials has a greater negative impact on several beneficial insects, however, increasing the odds of having to treat later for aphids and spider mites.
Some our early cotton is now beginning to bloom. Producers should be encouraged to assess internal damage to quarter-sized bolls by the end of the first week of bloom. Remember that weeks 3-5 of the bloom period constitute the interval when cotton is most susceptible to yield-reducing boll damage. This period of the recommended 10% internal boll damage threshold is when scouting really pays for itself - and then some. Stink bug levels appear to be healthy so far, although their potential damage to this year’s cotton crop will be determined over the next 5 weeks, primarily based on this crop’s attractiveness and susceptibility to brown and green stink bugs.
With heavy silking over most of the state’s field corn, it would appear at this time that the bollworm moth flight should be about on schedule. As contrasted to conventional non-Bt cotton, if a bollworm threshold is met, our 2-gene WideStrike and Bollgard II varieties often reach the treatment threshold in the range of 7 to 10 days or so later than the conventional varieties.
Looks like we are in for a hot week over much of the state beginning this Thursday, June 28. We’ll provide the next update this coming Thursday, July 5. Have a happy 4th.