Cutworms in Seedling Corn

DR. SEBE BROWN

 JACKSON, TENNESSEE

I’ve received a few calls in the past couple days on cutworms appearing in seedling corn. Below are some take home points on cutworms:

1. You probably do not need to worry about cutworms if you have kept a weed free seed bed for 2-3 weeks prior to planting, and this is especially true if using some of the Bt corn technologies (see below). However, the weather this year has not generally allowed for burndown applications made 3-4 weeks before planting.
2. Consider making an insecticide application near planting time. Relatively low rates of pyrethroid insecticides are typically effective for cutworm control. I do not recommend including an insecticide with herbicide applications that are made more than a couple weeks in advance of planting. Tank mixing an insecticide with an early burndown application may not be that effective. Cutworms you kill would have probably ‘cycled out’ before you planted. And because you cannot expect much residual control, there is the possibility of re-infestation between application and planting. The best time to make this application is within a few days before or after planting.
3. Using Capture LFR or other in-furrow pyrethroid insecticide as an in-furrow spray can add some protection against insect pests not completely controlled by seed treatments (e.g., cutworms and sugarcane beetles). I would prefer a T-banded type application where some of the product is applied to the “shoulders” of the seed furrow. This should improve control of cutworms compared with an application where 100% of the product is applied in-furrow. However, in-furrow applications appear to provide adequate control of cutworms in most circumstances.
4. No insecticide seed treatments should be expected to provide substantial control of cutworms. However, I have seen Poncho 1250 kill small cutworms in the past, don’t bet the farm on this though. Some Pioneer corn seed now includes a base treatment of Lumivia (chlorantraniliprole). This product should provide at least some control cutworm, but data is limited.
5. Although Bt corn and cotton traits provide some protection against cutworms, planting into fields that are heavily infested can be risky. Bt corn traits such as Leptra, VT2 Pro, SmartStax, Viptera, ad nTrecepta corn can reduce cutworm injury. Vip corn (Leptra, Trecepta, Viptera) will provide the best protection from a Bt stand point. However, large larvae are much less susceptible to Bt toxins. ∆

DR. SEBE BROWN: University of Tennessee