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No. 13/June 22, 2001

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Corn Rootworm, Grape Colaspis, and Japanese Beetle Adults Are Emerging
The first report of western corn rootworm adult emergence has been received, so it's time to start watching for both northern and western corn rootworm adults throughout the state. Reasons to scout for rootworm adults in corn will be to watch for silk-clipping injury that interferes with pollination and to assess the potential for injury in corn in 2001.

This article also discusses grape colaspis and Japanese beetles.

European Corn Borer: First-Generation Update
So far this season, reports of European corn borer activity have been widely scattered throughout the state. Some borers have entered midribs of corn plants. Once corn borer larvae begin to occur in midribs, in very short order, they start to tunnel into stalk tissue. Once this development takes place, rescue treatments are no longer an effective option. Producers are urged to monitor their cornfields carefully for any signs of whorl feeding and midrib injury as soon as possible in central and northern Illinois counties.

More News About the Soybean Aphid
An extension entomologist at Michigan State University has reported finding aphids on June 15 in a 3-acre research plot on the Michigan State University campus. These are small beginnings, but they are notable.

The article mentions two Web sites that will include reports of soybean aphids this year, the Soybean Aphid On-line Reporting and Mapping System and the Illinois IPM Web site.

Soybean Aphid On-line Reporting and Mapping System
The Soybean Aphid On-Line Reporting and Mapping System is now available on the North Central Pest Management Web site. The homepage contains a map of the United States and several informational links, including a photo image library, the online reporting form, and a PDF version of the Soybean Aphid Regional Pest Alert fact sheet. Each state designated with a pink dot on the map is active for mapping reports of soybean aphid observations.

Increase Your Vigil for Potato Leafhoppers
The hot, dry weather in a lot of areas of Illinois should encourage you to scout a bit more frequently for potato leafhoppers in alfalfa fields. Potato leafhoppers often cause more injury when the alfalfa plants are suffering from a lack of moisture.

Although we have not received many reports of alfalfa being treated for control of potato leafhoppers, I imagine that yellowing alfalfa may become more common soon.

Plant Disease Musings
The disease situation has been pretty calm this season. So far we have had scattered occurrences of seedling blight on soybean. The wheat crop also escaped with very little damage from fungal disease, and the corn crop is also starting off on a good foot from a disease-free perspective. Recent rains, though, should keep you on your toes in scouting for foliar leaf blights in corn.

This article discusses common rust and other fungal leaf blights.

Nitrogen Loss Update
The excessive late spring rains caused significant N loss through the processes of denitrification and leaching. The exact amount of N lost is hard to predict, but it is estimated that those who applied N in early to mid-October probably had between 50 and 90% of the N converted to nitrate by mid-May. Those who waited until November to apply the ammonia would have had between 60 and 40% converted to nitrate.

Farmers that have observed N deficiency in their fields in 2001 should consider applying additional N. The article includes a method for calculating the potential amount of N lost.

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 east-central, northern, southern, and west-central Illinois.

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

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