Stalk borer larve are developing in grassy areas across Iowa. They feed inside the culms of grasses and also in the stems of giant ragweed, marijuana, and other plants commonly found in fencerows, terrace backslopes, and grassed waterways. The larvae feed until they outgrow the grass or plant stem housing them, forcing them to move to new feeding sites, such as corn plants. Thus, damage is often limited to border rows that are adjacent to grassy, weedy areas. "Moving day" for the stalk borers starts when approximately 1,300 base-41 degree days have accumulated.
Iowa State University
Pope, Richard O., "Dates projected for stalk borer scouting" (2002). Integrated Crop Management News. 1813.
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