Refresher On Cutworms












DR. SCOTT STEWART

JACKSON, TENN.
   The comments below were posted sometime ago, but with corn planting time upon us, I’ve updated some take home points.
   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. Thus, consider making an insecticide application near planting time. Relatively low rates of pyrethroid insecticides are generally effective for cutworm control. I do not recommend including an insecticide with herbicide applications that are made more than two weeks in advance of planting. Tank mixing an insecticide with an early burndown application does not make much sense. Cutworms you kill would have probably ‘cycled out’ before you planted anyhow. And because you cannot expect much residual control, there is the possibility of reinfestation between application and planting. The best time to make this application is within a few days before or after planting.
   3. An additional point – 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 percent of the product is applied in-furrow. However, in-furrow application appear to provide adequate control of cutworms in most circumstances.
   A few other points for your consideration:
   • No insecticide seed treatments should be expected to provide substantial control of cutworms.  Pioneer corn seed now includes a base treatment of Lumivia (chlorantraniliprole). This product should provide at least some control cutworm, but there has been very little independent testing.
   • Although Bt corn and cotton traits provide some protection against cutworms, planting into fields that are heavily infested is a risky business.  Bt corn traits such as Herculex, VT3 Pro, VT2 Pro, SmartStax, and Viptera corn can reduce cutworm injury. However, large larvae are much less susceptible to Bt toxins. So if populations are high enough, I suspect any Bt technology can be overwhelmed.
   • Ammo 2.5 EC and its generic equivalents are not labeled for use in corn or soybean.
   • Refer to UT’s Insect Control Recommendations for Field Crops from a list of recommended products and rates. ∆
   DR. SCOTT STEWART: IPM Extension Specialist, University of Tennessee




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