D3443: Investigating the effects of cover crops planted before corn on the abundance of lepidopteran pests on Wisconsin farms

Cover cropping is a prominent conservation practice with significant benefits for soil and water quality. Incorporating cover crops into dairy and cash grain crop systems also has the potential to alter insect community dynamics. Producers in Wisconsin are increasingly integrating cereal rye (Secale cereale L.) cover crops into their corn-based rotations. However, several lepidopteran pests, such as true armyworm (Mythimna unipuncta Haworth), whose broad host ranges include cereal rye, have the potential to cause injury to the subsequent corn crop. This study aimed to compare the abundance of M. unipuncta in fields where corn was either planted after a cereal rye cover crop or into fields that had no previous cover crop on commercial farms and an agricultural research station in Wisconsin. Fields were sampled weekly using a pheromone lure and bucket trap from May to August to quantify adults. A subset of fields were scouted for larvae and potential feeding damage on corn plants. Results will be discussed in the context of increasing farmer awareness of how pests, and insects in general, respond to cover crops. This knowledge can assist farmers in decision making around chemical control options, the best timing for cover crop termination, and what species or mix of cover crop to utilize.