Corn Earworm – Vegetable Crops Hotline

Corn Earworm

Now is a good time to begin your plans for managing corn earworms (Figure 1) in your sweet corn. Below are several tips that will help you in this process:

  1. Make sure you have a corn earworm pheromone trap and earworm pheromones. See the article below for details.

    Figure 1. Corn Earworms

    Figure 1. Corn earworms

  2. Consider planting Bt sweet corn, especially for your later plantings that will be harvested in late July and August. If you choose to do so, use varieties that contain two sources of the Bt protein, including the Vip3A protein found in the Attribute II series. Varieties that only contain Cry1Ab proteins do not effectively control earworms in most instances.
  3. If you use a Bt variety, maintain a normal insecticide spray program. It’s not a good idea to think that the Bt genes will provide complete control. The combination of Bt and insecticides will help overcome the high populations of earworms late in the season.
  4. Consider the coverage you are getting with your sprayer. We did research last summer that showed that a boom with drop nozzles provided superior coverage and control compared to just a boom sprayer. However, one of the most useful results of our study was that it showed that you can attach water sensitive cards to the silks before you spray and get a good idea of the coverage your sprayer is providing and predict the level of control you should expect. Below is a picture of water sensitive cards from the plots with the boom sprayer and drop nozzles. This is the type of coverage you should aspire to if you want excellent control. If you are not getting coverage of this type, you should consider reconfiguring your sprayer until you do.
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