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Hi. This is Jack Bacheler, NCSU Extension Entomologist with the Wednesday Cotton Insect Update. It’s Wednesday, July 1.

This week we received a couple reports of both square retentions headed down toward 80% associated with sweep net samples in the 5 to 10 range per 100 sweeps – right about at the threshold level for plant bugs. In the cotton fields that we’ve checked this week, 90% or above square retention has been the norm. It’s hard to say at this point if we’ll be treating more than our typical small proportion of fields for plants bugs. On one hand, if this hot dry weather continues, cotton will likely become increasingly unattractive to plant bugs; on the other hand, alternative cultivated plant bug hosts like corn and various weed hosts are now drying down quickly, releasing adult plant bugs. In any event, this is a particularly good time to check square retention, with follow-up sweepings, if needed. If a foliar spray is triggered for plant bug levels just above the recommended threshold, chloronicotinoids like Centric or Trimax Pro are advised for their milder impact on beneficial arthropods, which in turn might help hold down possible subsequent cotton aphid and spider mite problems.

Presently, harder-to-control brown stink bugs, in various crops such as field corn, appear to greatly outnumber green stink bugs. Early preemptive sprays for brown stink bugs, which may or may not materialize as economic pests in the coming weeks, are not advised. Remember that our recommended thresholds for stink bugs are 50% internal boll damage during the first week of bloom and 30% during week two. The threshold then drops to 10% for weeks 3 through 5 or 6 of bloom when cotton is most vulnerable to yield loss from stink bug feeding medium-sized bolls.

We received several calls about spider mites along field borders and adjacent to mowed areas in the past few days, though so far none at treatable levels. With weather again predicted to be hot and dry for the coming week, spider mites are an ongoing concern, and assessments for the initial leaf stippling and reddening should be conducted at least weekly. If these initial evaluations reveal the above symptoms, further confirmation of live mites and the degree of infestation is needed. In North Carolina, treatment is recommended if mites are found on most plants and some lower leaves have abscised. Hold off on the treatment if significant rainfall is predicted with a day or two.

As far as we know, cotton aphids still appear to be behaving themselves.

Remember that our project works in relatively limited parts of our state each week. Please help keep us and others informed about possible insect buildups in your area.

I hope that next week’s July 8 Cotton Insect Update brings us news of either significant rainfall. See you then.