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No. 15/July 05, 2002

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Field Crop Session to Focus on Insects and Exotic Species
Crop producers, agribusiness dealers, and crop scouts are invited to participate in a workshop on July 24 emphasizing field crop insects and exotic weed and insect species. The workshop will include classroom sessions and in-field demonstrations.

Japanese Beetles Are Coming On Strong in Some Areas
During the past couple of weeks, Japanese beetles have made their presence known in several areas of Illinois, especially in southwestern and east-central counties. Reports of extremely large numbers of Japanese beetles have been common.

As corn matures, people will have to keep tabs on Japanese beetle activity during the pollination process. In most cornfields right now, Japanese beetles are feeding on leaves. In some fields, they are skeletonizing corn leaves. No yield loss usually occurs as a result of this type of injury.

Reports of Large Numbers of Grasshoppers Are Common
People throughout Illinois and in adjacent states have taken note of very large numbers of grasshopper nymphs in roadsides, ditch banks, grass waterways, and, in some instances, crop fields.

Continued hot, dry weather does not bode well for crops when grasshoppers are numerous. As the nymphs consume noncrop hosts and these plants dry out, they will move into adjacent fields of corn and soybeans, potentially causing serious defoliation.

Western Corn Rootworm Adults Are Emerging
Recent observations of the first western corn rootworm adults of the season are a little later than they were last year, but it was only a matter of time. After the cooler temperatures during May and early June slowed larval development, the recent hot temperatures sped up larval development, and it's likely that adult corn rootworms will begin emerging rapidly now. This article reviews their emergence patterns, their morphological features, and some of their behaviors.

European Corn Borers Inside Stalks in Most Areas
First-generation European corn borer larvae have tunneled into stalks in most areas of Illinois, and moths that will lay eggs for the second generation will be emerging soon. For the most part, infestations of first-generation European corn borers in Illinois this year were not economic. If European corn borers survived through the first generation, we will have to watch carefully during development of the second generation.

Spider Mites in Corn in Southern Illinois
We are more familiar with spider mite problems in soybeans, but spider mites can injure corn if the weather is hot and dry, allowing numbers of mites to build up to injurious levels. Watch the edges of fields first; symptoms of spider mite injury usually show up first at field margins.

Findings of Soybean Aphids Continue
We are in the period when soybean aphid populations are increasing throughout the Midwest, so observers continue to report finding them. At some point in the near future, the focus will shift from distribution to population size. However, right now it's important to share some of the information about where soybean aphids have been found.

Imported Longhorned Weevil in Soybeans
Matt Montgomery, Extension educator in crop systems in Springfield, has found a pest of soybeans that we don't encounter very often in Illinois. He found imported longhorned weevils in a field of soybeans in Sangamon County. This insect rarely causes economic damage to soybeans, but it can cause considerable injury in early vegetative stage soybeans when a large population is present.

Corn Leaf Diseases and Fungicides for Their Management
Although many corn leaf diseases occur in Illinois, some common diseases in one or more areas of the state are rust, gray leaf spot, eyespot, northern leaf spot, and northern corn leaf blight. This article provides a brief description of the first three of these diseases; factors contributing to their development; and management tactics, including fungicide options for susceptible inbreds.

Regional Reports
Extension Center educators, Unit educators, and Unit assistants in northern, west-central, east-central, and southern Illinois prepare regional reports to provide more localized insight into pest situations and crop conditions in Illinois. The reports will keep you up to date on situations in field and forage crops as they develop throughout the season.

This week's issue include a report from northern Illinois.

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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