Alabama Cotton Insect Situation: July 1, 2022

We have gotten some rains over the past week, although some of it was still isolated. Hopefully this will help kick the crop back in gear and get moving. We are starting to find more blooms, particularly in central and south Alabama, but we likely have some blooms in fields in the north as well.

Adult tarnished plant bug

Plant bugs are still the hottest ticket in town. Over the past few days, we have received reports of up 3-4x threshold populations in northeast (Cherokee Co.) and north central Alabama (Lawrence/Morgan Co.) and we have observed threshold populations in central Alabama and the Tennessee Valley as well. The common theme is older cotton and cotton that had not yet been sprayed for plant bugs. While fields that have been treated still have a plant bug here or there, we do not appear (as of yet) to be dealing with much re-
infestation of these fields. Reports out of the Wiregrass are that plant bug numbers appear to be relatively low. Some fields may have numbers and other do not. I spoke with our colleague across the line in Georgia, Dr. Phillip Roberts, he shared with me that while a lot of acres in central GA are being treated, folks are calling about low numbers in SW Georgia. So what we are hearing about in the Wiregrass (lower numbers) appears similar across state lines. We are hearing similar reports from the Southwest Alabama. The plant bug situation changes from field to field.

One thing to keep in mind is that plant bug pressure is often higher near field borders with corn. Corn is a good host for plant bugs. Typically, movement out of corn is expected around the time the silks begin to turn brown (R2 or the “blister” stage), but the movement could be before or after that stage depending on when the original egg lay occurred. Unlike with stink bugs, however, we do not recommend spraying corn for plant bugs. It just won’t help the corn (plant bugs are a non-pest), and plant bugs aren’t as “hemmed up” in corn like stink bugs.

In terms of treatment options, we still like the neonicotinoid products on migrating adult populations (imidacloprid or Centric). While these products, and particularly imidacloprid, won’t provide 100% control, they often provide enough to reduce populations below threshold and maintain square retention above 80%. As we get into bloom and start finding nymphs, we change from the neonics to chemistries like Transform, acephate, Bidrin or pyrethroids (depending on location in the state). Around 1^st bloom is also a good time to get Diamond in the mix. This insect growth regulator provides control of immature plant bugs and may be enough when combined with a knockdown insecticide to get us to the stink bug window (≈3^rd week of bloom).

Thumb-sized boll 
damaged by stink bugs.

Speaking of stink bugs, we are expecting this to be a heavy stink bug year. Our observations and reports from corn suggest high populations are out in the landscape currently. Although stink bugs prefer to feed on bolls about 10-12 days old (about an inch in diameter), they will feed on thumb-sized bolls if nothing else is around to feed on. The presence of stink bugs in early bloom cotton may influence plant bug material choices. Keep in mind our threshold for stink bugs during early bloom is 30-50% internal boll damage.

Even after the rains, we still have some spider mites in fields. Hopefully rains will knock back populations and let the cotton outrun them. Keep in mind that rain will not outright kill mites or eliminate them from a field. If you had some in fields prior to a rain, they can blow back up pretty quick if conditions allow. I am not sure that we have many fields that need to be treated for mites right now, but they are something to continue to monitor.

As always, if we can be of any help, please let us know.