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No. 17/July 19, 2002

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Insects and Hot, Dry Weather--A General Statement
In many areas of Illinois, the stress on crops from hot, dry weather has been exacerbated by insect problems. Injury caused by corn rootworm adults and Japanese beetles has added stress to crops already stressed by a lack of moisture. And some insects benefit directly from hot, dry weather conditions.

With these problems occurring at the same time in some areas and with the second generation of European and southwestern corn borers looming, making control decisions is becoming more difficult.

Japanese Beetle Woes Continue
Japanese beetles continue to cause problems for corn and soybean growers in many areas of Illinois. In some counties, infestations are spotty; in other counties, most fields seem to be infested. Reports of silk clipping in cornfields and defoliation in soybean fields are common, and insecticide applications to prevent further injury are warranted in many fields.

Corn Rootworm Larval Injury and Dry Weather: Not a Good Combination
Reports of large densities of western corn rootworm adults are common across much of the northern half of Illinois. This article discusses why we are experiencing another summer of rootworm problems in central, east-central, and northern Illinois.

Corn Leaf Aphid Colonies Are Increasing in Size
A well-known pest during hot, dry seasons, the corn leaf aphid is making its presence known in some areas of the state. Population densities are high in some fields in central Illinois, and the potential exists for these pests to interfere with pollination.

This article contains information about scouting, effects on yield, treatment guidelines, and suggested insecticides.

Prepare for Second-Generation European Corn Borers
With all of the other concerns, the second generation of European corn borers could sneak up on us. The stage has been set for a fairly significant second generation because many fields harbored sub-threshold levels of first-generation European corn borers. If the borers survived reasonably well through the first generation, densities of second-generation populations could be significant.

This article includes a worksheet designed specifically for making decisions about managing second-generation European corn borers.

Status of Soybean Aphids
We haven't had much to report about soybean aphids this season, but they still bear watching. Populations of soybean aphids in Illinois have been small thus far in 2001, but as we have stated in the past, their numbers can build rapidly.

Twospotted Spider Mites Continue to Threaten Soybeans
Twospotted spider mites were first noted in fields in southern Illinois, but now they are showing up elsewhere. As the hot, dry weather has continued, densities of spider mites have been increasing in size rather quickly.

This article contains a description of the pest and information about scouting and management.

A Few "Thumbnail Sketches" of Insect Occurrences
This article contains information about a few insect situations that are worthy of note, including bean leaf beetles, grasshoppers, potato leafhoppers, insects interfering with weed control, and fungus beetles.

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 includes reports from northern and west-central Illinois.

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

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