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No. 14/June 29, 2001

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The Search for Soybean Aphids Intensifies
After learning that entomologists at the University of Minnesota and Michigan State University had found soybean aphids in soybeans in their respective states, we intensified our survey efforts to determine whether this invasive pest had begun to colonize soybean fields in Illinois. More recently, entomologists at the University of Illinois found soybean aphids in a small field on the South Farm on June 25 and 26. This finding in Champaign County represents the most southern occurrence of the aphids in Illinois thus far.

At this point, it's way too early to try to do anything about the pests. If you decide to begin looking for soybean aphids, please make certain to accurately identify any insects you find.

Reports of Silk Clipping by Japanese Beetles
In last week's Bulletin we reported the first Japanese beetles of the season in Monroe County on June 20, very similar to last year's first sightings of this insect pest. This week we have images of Japanese beetle adults feeding on corn silks. We have also received reports of Japanese beetle adults feeding on red clover blossoms and reports of Japanese beetle adults in cornfields and soybean fields in Fayette and Shelby counties.

In the coming weeks of July, corn growers are urged to monitor their pollinating fields for Japanese beetle adults and their silk clipping activities.

Grasshopper Nymphs Are Out and About
Doug Gucker reported numerous grasshopper nymphs feeding on soybean plants this week. As you continue to scout fields for key insect pests, add grasshoppers to your list of pests to keep an eye on.

This article discusses the life cycle of the grasshopper.

Parasitoids of Armyworms Have Been Common
In the aftermath of the significant outbreak of armyworms in Illinois and elsewhere in the Midwest, many keen observers have found white, cottony masses that appear to be either eggs or cocoons. Some people have feared that they had found armyworm eggs. However, we have learned from photographs and specimens sent to us that the white, cottony masses were cocoons of a parasitic wasp, tentatively identified as Glyptapanteles militaris in the family Braconidae. This parasitoid attacks armyworms as well as several other caterpillars.

Is Anyone Concerned About Corn Borers?
The telephones have been relatively silent, and the Internet wires are pretty cool right now, at least as they relate to European corn borers. We are aware of only a few instances where corn borers might pose a threat that will require action. In southern Illinois, European corn borers have been very hard to find.

Maintain a vigil for both species of corn borers and let us know what you observe. We've skated through the first summer month with little impact from either one, but favorable environmental conditions could tip the scales in the borers' favor.

More Lepidoptera to Watch For
Although European corn borers have not been as aggravating as their brethren, there still is time for them and other Lepidoptera to give us headaches. Therefore, a couple of somewhat unusual situations bear reporting in this article.

The article discusses the thistle caterpillar and the painted lady butterfly, and the whitelined sphinx caterpillar.

New Insecticide (Tracer) Labeled for Use in Field Crops
Tracer had been registered for use on cotton, but the label was revised in early May to include registrations for use on field corn, seed corn, popcorn, teosinte, wheat, barley, buckwheat, rye, and oats. Tracer also is registered for use on sorghum, milo, pearl millet, proso millet, grain amaranth, and soybeans.

We have had limited experience with this new insecticide. However, we will search for efficacy data and offer some information about its performance in trials throughout the United States.

Alfalfa Blotch Leafminer Found in Several Illinois Counties
Renewed survey efforts this year have revealed that the alfalfa blotch leafminer has spread considerably in Illinois. This insect has not been reported to cause much, if any, economic damage to alfalfa in the Midwest. However, its presence is worth noting.

Corn Stunting and Uneven Growth--Is It the Result of a Disease?
There are many potential reasons for corn to be stunted this year in Illinois. The list of possible reasons includes herbicide damage, sub-optimal fertility, soil compaction, wet/flooded conditions, dry conditions, insect damage, cool weather, root diseases, and other factors. Some of the causes are poorly understood.

This article discusses factors that influence stunting and uneven growth and focuses on disease that may cause these effects at this time of the year.

Crunch Time for Corn
The latest crop condition report indicates that the Illinois corn crop is almost as tall as the 2000 crop was at this date, with 96% of the crop rated as being in fair-to-excellent condition. The crop is well ahead of average development for this date, similar to last year's. Tassels are starting to appear in some early-planted fields, especially those with early hybrids. There are differences between the two crop years, though, and we might consider what if anything threatens the current crop, using last year's crop for comparison.

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, southern, and west-central Illinois.

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

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