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Vol. 17, No. 11
Article 3 of 5
June 1, 2007
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Grasshoppers Nymphs Numerous Central and Southern Missouri By Wayne Bailey Moderate to high numbers of small grasshopper nymphs are common in grass pastures, grass field margins and waterways, and to a much lesser extent in no-till soybean fields. Grasshopper nymphs may continue to emerge from eggs for another two weeks. Although typically a late summer pest on field crops, this year high numbers of grasshopper nymphs have emerged in field borders, grass pastures and no-till soybean fields. They have the potential to cause serious defoliation and some stand loss as they grow in size. At present, most nymphs are newly emerged from eggs and currently range from 1/4 to 1/2 inch in length. They will rapidly increase in size over the next few weeks. Typical grasshopper damage consists of irregular shaped holes extending from the leaf margin to the center of the leaf. Grasshopper damaged foliage often has a thin border of dead tissue surrounding the feeding site, unlike caterpillars which leave a smooth green surface at the feeding site. The following table lists the economic threshold for grasshopper infestations in non-cropland areas, grass pastures and soybean. Also included is a listing of recommended insecticides and a range of use rates for formulated material per acre. It is generally accepted that small grasshoppers are more readily killed than older hoppers by the same rates of insecticides. Regardless of size, grasshopper control is best achieved with the use of high rates of water and moderate to high rates of insecticides. Be sure to read and follow all pesticide label directions and precautions.
Wayne Bailey | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
