Scout corn now for black cutworm and rootworm threats

May 27, 2024


As June approaches, farmers should be vigilant against insect pests in their cornfields. The University of Illinois Extension identifies two key threats: black cutworm and western corn rootworm.

Black cutworm larvae are now large enough to inflict significant damage by cutting down corn plants. Scouting is crucial, especially in fields with poor winter weed control. Look for cut plants and check the surrounding soil for larvae with a characteristic sheen. If 2-5% of plants are cut with larvae present, consider an insecticide application.

Western corn rootworm egg hatch is reaching its peak in Illinois. Root feeding by these larvae is expected until late June. Planting delays can reduce rootworm threats as hatched larvae may not find established roots. However, root feeding damage will be evident in a month, allowing farmers to assess control effectiveness.

The western corn rootworm's ability to adapt to control methods necessitates monitoring field performance to determine the best future strategies. This pest has historically caused significant economic damage to corn crops.

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