Stalk borers can cause stand loss in corn adjacent to grass terraces, waterways, ditches, and fencerows, and especially those areas where stand loss has occurred in previous years. Usually the larvae don't crawl very far from grass, so the problem is often restricted to the first four rows of corn next to grass. The smaller the corn, the more likely it is to be killed by stalk borers. Once corn reaches the 7-leaf stage (V7 stage), stalk borers are unlikely to kill the plants.
Iowa State University
Rice, Marlin E., "Stalk borers love giant ragweed -- and corn" (2005). Integrated Crop Management News. 1472.
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