Monday, 18 November 2002
D0144

This presentation is part of : Student Competition Display Presentations, Section F. Crop Protection Entomology

Alfalfa responses to simulated clover leaf weevil injury and the development of economic injury levels

Rodney A. Madsen, Leon G. Higley, and Thomas E. Hunt. University of Nebraska, Department of Entomology, PI 214 East Campus, Lincoln, NE

The clover leaf weevil (Hypera punctata) is a sporadic but potentially serious pest of alfalfa in Eastern Nebraska. Although similar in appearance to the alfalfa weevil, the clover leaf weevil is much larger. Unlike the alfalfa weevil, the clover leaf weevil overwinters as a larva and feeds primarily on the lower and middle leaves of the canopy. Under the right conditions a combination of late stage clover leaf weevil larvae and newly emerged adults may cause damage to first growth alfalfa in the early bloom stage. The extent of this damage is unknown. A study simulating adult clover leaf weevil feeding was conducted in an alfalfa field at the Haskell Agricultural Research Lab near Concord, NE in May 2001 and 2002. The general objectives were to determine the effects of clover leaf weevil feeding on alfalfa and to develop economic injury levels. Results indicate defoliation injury from clover leaf weevil feeding does not produce significant phenological delays from the completion of the defoliation to first harvest. Nutrient quality was not significantly affected by defoliation injury in the first growth cycle. Alfalfa development was also not significantly affected in the second growth cycle. The most important effect of defoliation initiated at the early bud stage of the first growth cycle was to reduce the dry matter yield through leaf removal.

Species 1: Coleoptera Curculionidae Hypera punctata (Clover Leaf Weevil)
Keywords: alfalfa, defoliation

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