Thrips

John Van Duyn, North Carolina State University, Entomology Extension Specialist

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The "soybean thrips" and other thrips species feed and reproduce on the leaves and buds of soybean seedlings. Their feeding creates bleached-out lesions along the leaf veins and gives a silvery/bronzed appearance to the leaf surface when damage is severe. Most often damaged plants will have numerous black and white, cross striped adult thrips and yellow immature thrips on the leaves; these insects are very small (less than 1/10 inch) and are torpedo shaped. While thrips always occur on soybean seedlings, it is only during outbreak years that they cause concern. In particular, during dry weather and on earlier planted full-season soybeans, thrips populations can soar when plants are growing slowly. Under these circumstances thrips injury will occasionally kill seedlings. Other stressors, such as herbicide injury, can add to thrips damage and cause plant loss. Although plants may look very poor, thrips seldom justify insecticide treatment except in cases where severe defoliation and plant loss is a possibility. Also, research has indicated that severe thrips injury may increase damage from post emergence herbicides that cause leaf burn, like Blazer. Although thrips may occasionally be a problem, treating for thrips with an at- planting systemic insecticide is not warranted in soybeans. These products may produce a healthier looking seedling, but research has not shown any yield effect.

Soybean Page

Other Resources

    1. North Carolina Agricultural Chemicals Manual
    2. North Carolina Cooperative Extension Service

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This page (http://www.ces.ncsu.edu/plymouth/pubs/thrip.html) was created by John W. Van Duyn Ph D. Extension Entomologist, Wayne Modlin, Res. Tech. III.

Date Created 2/22/00.
Last revised on 2/04/04.

Published by North Carolina Cooperative Extension Service

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

CAUTION: The information and recommendations in these Notes were developed for North Carolina conditions and may not apply elsewhere.