Thursday, June 16, 2022

Alabama Cotton Insect Situation: June 16th, 2022

We still have some thrips going in spots here and there, but we are mostly through that window. Plant bugs and spider mites are the biggest calls and reports that we are getting.

As more cotton is starting to square across the state, we are receiving more reports of adult plant bugs moving into fields. Remember our thresholds are 2 adults per 25 sweeps (8 in 100 sweeps) or 80% square retention in the upper 2 or 3 nodes of the plant.

One important thing keep in mind is that thresholds are more of a guideline than a hard and fast rule. The proper term is “economic threshold” which obviously means economics play a role (both commodity and input prices). Due to the fluctuation and variations of prices, we don’t change our thresholds each year, but we can adjust a little bit “on the fly” if we need to. With cotton prices hovering over a dollar, we can afford to be a little more aggressive with insect management. This is because even though the insects are “eating the same amount of cotton” they are eating “more money” because that cotton is worth more. This is not to say that scouting and thresholds aren’t important in years with high prices, an application with no insects in the field is still a waste, just that pulling the trigger a little sooner may provide a higher return. Of course, in years where prices are low, the opposite is true.

Early spider mite symptoms

We got some storms across Alabama yesterday, and that may help the spider mite situation a little bit, but I wouldn’t bet on it. With the temperatures across the state right now and projected to be even hotter next week, every insecticide application should consider spider mites. We are in a situation where they could blow up quick. I am not saying don’t treat plant bugs if you have economic infestations for fear of spider mites but try to choose something less likely to flare them. Our threshold is to treat when 30% or more of plants are infested with spider mites and damage is evident. Sometimes we may watch the forecast and see if an imminent rain can help us before we make an application. I am not sure I would do that with the current outlook. I think being a little more proactive on these building populations with upper 90’s and even into the 100’s temperatures impending would be prudent.

Mating southern green stink bugs in corn

I also want to briefly mention stink bugs. We have been in corn fields in central and SE Alabama this week collecting corn earworms for Bt resistance monitoring. There is currently a ton of adult stink bugs in corn fields that are mating, and some nymphs are beginning to emerge as well. Corn is the perfect trap crop for stink bugs and cotton. A well-timed application will help corn and cotton as well. The best time to spray is at tassel, while the ears are forming, but stink bugs can damage corn through the R2 (blister) stage. Most labeled pyrethroids provide good control. If you haven’t, consider making an application in corn, it will help that crop and likely relive some pressure in cotton later in the year as well. For more information on managing stink bugs in corn, watch this video (link) with Eddie McGriff and Dr. Katelyn Kesheimer.  

We will also give a reminder that we have two more scout schools (link) this coming week. We will be at the TN Valley REC in Belle Mina on Tuesday the 21st with registration starting at 8 and the program beginning at 8:30. We will also be in Centre at McCord’s Fire Station #1 on Thursday the 23rd. That program will begin at 10 am.

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