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Agronomy Day 2009

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Tour B

New Changes and Old Challenges: Western Corn Rootworm Management in Illinois

Ronald E. Estes
Ronald E. Estes
Senior Research Specialist
Department of Crop Sciences
(217) 265-4113 restes@illinois.edu
Nicholas A. Tinsley
Nicholas A. Tinsley
Graduate Research Assistant
Department of Crop Sciences
(217) 265-4113
tinsley@illinois.edu

The western corn rootworm continues to remain the most significant insect pest of corn in Illinois. Nationally, costs associated with yield-loss and management are estimated to reach over $1 billion each year. Western corn rootworms were initially detected in Illinois in 1964. Soon thereafter, crop rotation was recommended to manage this pest because it thrived in continuous corn environments. In continuous corn cropping systems, soil-applied insecticides were used at planting to prevent economic losses. While soil-applied insecticides continue to offer protection from western corn rootworms, crop rotation began to fail as a management tactic in the mid-1990s, following the development of a variant western corn rootworm population that will lay eggs in crops other than corn, including soybean, alfalfa, and wheat. However, the options for managing western corn rootworms in Illinois are robust and include old standards (e.g., soil-applied insecticides), newer tactics (e.g., seed-applied insecticides, Bt hybrids), and combinations thereof.

The Insect Management and Insecticide Evaluations program at the University of Illinois has been conducting field trials since the mid 1980s to help answer questions about how to control this sometimes unmanageable pest. Just as western corn rootworms have evolved, so have the means to control them. Throughout the 80s and 90s, soil-applied insecticides were the standard control tactic against western corn rootworm larvae. In the past two decades, the development of Bt rootworm hybrids and insecticidal seed treatments have been added to the arsenal. In the past few years, companies have begun to recommend using a soil-applied insecticide in addition to a Bt rootworm hybrid, a practice that still needs further evaluation. We plan to discuss all of these tactics, from the old to the new, and share with you some preliminary results from trials that we are conducting in 2009.

rootworm damage rootworm damage rootworm damage

change and challenge