Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on April 24, 2017. The information contained within may not be the most current and accurate depending on when it is accessed.
Landscape diversification, including the use of cover crops, can provide habitat and forage for beneficial insects. This is especially true in the spring when there is a lack of food. Alternatively, cover crops can also support field crop pests, including moths, beetles, flies and slugs. The early spring vegetation, sometimes called a “green bridge,” provides resources until the row crops emerge. In the past, several green bridge pests have become common in Iowa.
Biology: widespread U.S. pest that migrates to Iowa annually; 2-3 generations each summer; females attracted to grass and lay egg masses in aggregated areas.
Injury: caterpillars are mobile and nocturnal; young caterpillars skeletonize leaves but leave the midrib behind; older caterpillars can consume leaves; VE-V5 corn and V(n) soybean is most susceptible; significant stand loss is possible.
Biology: widespread U.S. pest that migrates to Iowa annually; 2-3 generations each summer; females attracted to green vegetation lay eggs randomly.
Injury: caterpillars are mobile and nocturnal; caterpillars defoliate leaves and tunnel in plant, and are capable of cutting seedlings at soil; VE-V7 corn and V(n) soybean is most susceptible; significant stand loss is possible.
Common stalk borer
Biology: widespread U.S. pest that overwinters in Iowa; 1 generation each summer; females randomly lay eggs along ditches in fall.
Injury: caterpillars are mobile; young caterpillars infest grass and older caterpillars infest corn, soybean and ragweed; V5-V10 corn and V(n) soybean is most susceptible; significant stand loss is possible but aggregated at field edges.
How to scout for pests in cover crops
- Walk through fields and note defoliated, clipped or shredded leaves; and dying, dead or missing plants
- Look for frass pellets and webbing in and around plants
- Dig around plants, move debris, pull plants, spilt stalks and look in soil crevices