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This is Jack Bacheler, extension entomologist at NCSU with the cotton and soybean update. Today is Wednesday, June 21.
Although things are generally quite on the cotton insect front, we have had several reports of cotton aphid infestations during the past week, thankfully not yet at treatable levels in these cases. With most reports, the brown to tannish aphid mummies were present; in one case, ladybird beetles were also aiding in reducing the aphid population. To my knowledge, even with our more recent very hot dry weather, we do not yet have visible moisture stress on cotton. This more typically can occurs when cotton begins to set bolls and the combination of this stress along with significant cotton aphid feeding can sometimes add up to treatable situations. If treatment is needed, the nicotinoids and Carbine still most often provide adequate to good aphid control here. Only one chloronic resistant aphid outbreak in 2011 has been brought to my attention. In this instance, 5 to 6 possible cotton aphid exposures to chloronics took place between the seed treatment, a plant bug spray, 2 combination stinkbug/bollworm sprays and one to 2 unsuccessful sprays for cotton aphids. In most cases at this time of year we can afford to be patient, though the generally very effective cotton aphid fungus does not tend to show up here on cotton aphids until the second or third week in July. Hopefully, this early year will bring on the fungus earlier.
Although are only now getting into the “plant bug season”, we would advise checking plants when squares begin to develop. Thankfully, it is very unusual here in the Southeast to get high enough plant bug levels to cause “crazy cotton” resulting in terminal loss in pre-squaring to cotton. If we get reports of plant bug damage and square loss, they should begin in the next few weeks.
The twospotted spider mite is a pest that seems to benefit from hot dry weather, so now would also be a good time to begin to look for mite outbreaks. Although often more likely along field borders, mites can also develop from within cotton fields, particularly in reduced till fields, including fields in which the burn-down herbicide was applied late.
We would again urge producers to check soybean fields prior to treating for kudzu bugs. A few fields have been treated this past week for what appeared to be very low sub-economic levels of this new pest. It’s not difficult to find decent levels of kudzu bugs on the stems of plants in perimeter rows and even within soybean fields, and still not come up with 15 adult bugs per 15 sweeps in the field interiors. We are beginning to get some reports of dead kudzu bugs in untreated soybean fields - that is, no seed treatments and no foliar insecticides. We hope this may signal the beginning of the end for this adult generation on early beans, though what these adults leave behind in the way of egg masses and nymphs is our next area of potential concern. From several planting date/maturity group studies in North Carolina, it’s certainly easy to see that our April-planted group IV beans are far more attractive to kudzu bugs than subsequent planting dates and later maturity groups. We can only hope that kudzu bugs will give beans planted behind wheat a break, at least until the expected later major flights. To put this all in perspective, most soybean fields in North Carolina do not presently have treatable levels of kudzu bugs. However, things can change and we’ll keep you posted in the coming weeks.
See you next week on June 27. See you then.