Alabama Cotton Insect Situation: June 6, 2022

Things were pretty quiet last week, but the Alabama Cotton Insect Situation seems to be picking back up this week. We have already gotten a few calls about threshold levels of adult plant bugs in squaring cotton in in Central and SW Alabama. If you remember last year, we had a big migration of adult plant bugs into cotton fields statewide around June the 15^th. At this point, adults are moving into our oldest cotton (mid-April to first week of May) that is starting to put on squares. So, most of our fields aren’t at risk yet, but keying in on fields that are squaring is important. Much of the fleabane across the state has already or is starting to play out. This means plant bugs are looking for somewhere to go and a cotton field that is starting to square is a good place for them to settle in. Reports out of the TN Valley and NE Alabama are that not much cotton is squaring, and no threshold levels of plant bugs have  been observed.

Adult Tarnished Plant Bug

With input and cotton prices where they are, it’s going to be important to scout fields and be prepared to treat when necessary. Prior to bloom, our thresholds are 2 adult plant bugs per 25 sweeps or 80% square retention in the upper 2-3 nodes. One thing to keep in mind is that we may scout a field with high square retention, but also high numbers of plant bugs. That may mean that the bugs just moved into the field and that squares that were fed on haven’t yet had time to abort. That’s why we like to use these thresholds as an either/or and a both/and. In other words, if you hit one of the thresholds but not the other, we should go ahead and trigger a spray.

In terms of recommendations, we like to manage migrating adults as economically as possible, because there is always the potential for more to move in a few days after a spray. Unfortunately, nothing will provide much residual control of migrating adult plant bugs. I have heard some reports that some of our “June go-to’” products are hard to get. We have some options, such as imidacloprid (highest labeled rate), Centric (1.5-2oz), acephate (8-10oz) and depending on resistance in your region, bifenthrin (6.4oz). Keep in mind that per the label, Bidrin cannot be applied between pinhead square and first bloom.

Another thing to remember is that square retention is a good way to evaluate the efficacy of an insecticide on migrating adults. If you come back to a field 5 or 7 days after a spray and find as many or more plant bugs, good square retention will tell you your spray worked, and more bugs have moved into the field.

We should be through the thrips window for much of our cotton, some fields, particularly in north Alabama, may still need to be watched. As a general rule, we don’t see much value in spray cotton beyond the 4^th true leaf stage, but we have seen some fields this year that would very likely benefit from a spray at the 5^th or 6^th leaf.

Early spider mite symptoms on leaves

The last thing I will mention is that we observed spider mites in a field in central Alabama today. It has been an interesting start to the season variable weather, most too dry and some too wet at times. These mites had likely been building on some weeds that were in the field and have moved into the cotton after a herbicide application went out. In dry areas, spider mites are another thing to consider when making insecticide application decisions. Hopefully the chances of rain across the state this week will materialize so we can get some reprieve and help get this cotton crop off and running.

The 63rd Alabama Cotton Scouting School is coming up. This year we have our 3 traditional locations: Tuesday, June 14^th in Autaugaville, Wednesday June 15^th in Headland and Tuesday, June 21^st in Belle Mina. We will also have an in-season scouting update in Centre on June 23^rd and a late season scouting update in Southeast Alabama in August. More information can be found here.

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