Alabama Cotton, Soybeans: Insects Mostly Quiet, Redbanded Stink Bugs a Concern

Cotton

Overall insect activity in Alabama is quiet. We are finding low levels of aphids in many fields, and a few tarnished and clouded plant bugs in nearly every field. But we haven’t seen any at treatable levels recently. Spider mites are in a number of fields. The longer we stay dry, the worse the spider mites will get.

Stinkbug pressure varies from field to field. They are quietly building. Two issues influence stinkbug populations: proximity to corn or peanuts and the size of the field. Populations will be higher close to corn or peanut fields. They move out of corn when it dries down. They don’t do any harm to peanuts, but they move to cotton from peanuts all season long.

Field size impacts populations because stinkbugs don’t fly well. In fields that are 75 acres or larger, it takes a long time to get to threshold level. Ideally, we could make border sprays. However, border sprays aren’t practical for many growers who have large fields spread across a wide area.

We haven’t had any bollworm calls on 2-gene cotton. If we look long enough, we can find an escaped worm but they’re at a very low level and in central and south Alabama we are already past the moth flight out of corn. Since we are past the flight and we still don’t have many escaped worms, it looks like it’s going to be a light year.

The pest we are most concerned about going forward is the silverleaf whitefly. We don’t think we have any fields infested yet, but we are checking likely areas again on Thursday (7/30).

Where we have moisture, we are really putting a lot of fruit on cotton. We really would like to have a rain over most of the state this week.

North Alabama Bollworm Flight Upcoming

As we approach the historic flight dates for the TN Valley, we are hearing reports of bollworm eggs on bloom tags in cotton in Belle Mina. Moth trap counts haven’t peaked yet (as of 7/31) but we expect it any day now. Instead of spraying on eggs, in Alabama we still recommend giving the 2-gene Bt technologies (e.g., Bollgard 2) the opportunity to work.

Thresholds vary for fields that have been sprayed previously with disruptive insecticides (TH= 5 (0.25”) larvae per 100 plants) or have not been sprayed (TH= 10 (0.25”) larvae per 100 plants). The good news is that in our research plots in Prattville the 2- and 3-gene Bt technologies are holding up well.

Current recommended thresholds, insecticides and rates can be found in the Alabama Cotton IPM Guide.

Soybeans

We have had more acres infested and subsequently sprayed for redbanded stink bugs (RBSB) in the western portion of the Black Belt region. We need to be scouting fields to ensure we do not get behind on this pest.

The RBSB can be difficult to “spray our way out of” once it establishes in a field. Tank-mixtures of acephate and pyrethroids or neonicotinoids usually provide good control.

If you run into any RBSB or think you may have some, don’t hesitate to give us a call if you have any questions.

Current recommended thresholds, insecticides and rates can be found in the Alabama Soybean IPM Guide.




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