I’m getting more calls about a fair number of green cloverworms and scattered, below-threshold loopers, primarily in later maturing soybean fields. Please refer to last week’s article about knowing the difference and recommended treatment thresholds for these pests. I wanted to make an additional point or two.

Green cloverworms are easy to kill with pyrethroid insecticides at moderate rates. There is a risk of creating a future infestation of soybean loopers by eliminating natural enemies. Although it appears that we could have an above average year for soybean loopers in late maturing fields, there is no guarantee this will occur. This leaves you with two primary options when treatment for green cloverworm is needed.

1. Use a pyrethroid insecticide for green cloverworms such as Baythroid, Brigade, Karate, Mustang Max, etc.  … and deal later with soybean looper infestations if they occur (often in late August and Early September). This is a cheap fix.
2. Or use an alternative chemistry that is less likley to flare infestations of loopers. These products are going to be more expensive and only effective in controlling caterpillar pests. There are a lot of options (please see below for the minimum rates listed on the labels). Because green cloverworms are easy to control, you can make things cheaper by using rates below those listed on the label for at least some products. But my hands are a tied when it comes to recommending below labeled rates.

Belt (2 oz)
Blackhawk (1.5 oz)
Dimilin (2 oz)
Intrepid (4 oz)
Intrepid Edge (4 oz)
Prevathon (14 oz)
Radiant (2 oz)
Steward (5.6 oz)

A third option is to run standard rates of products such as Prevathon, Besiege, or Belt and hope that the residual control will provide long enough protection to prevent a treatment for loopers down the road. Personally, I think this is a big investment for something that may not occur. It is also a good way to unnecessarily select for resistance.

I should point out that some level of resistance of soybean loopers to diamide insecticides such as Belt, Besiege, and Prevathon is already suspected in some areas of the U.S. (although certainly not confirmed in the Mid-South).