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No. 17/July 20, 2001

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Time to Step Up the Vigil for Soybean Aphids and Spider Mites
If you haven't done so already, you should increase your search efforts for soybean aphids in soybean fields. And while you're at it, look for twospotted spider mites, too. Although numbers of soybean aphids are relatively low in most fields, numbers have built up to very noticeable levels in some areas.

There is little doubt now that soybean aphids have become established in the United States. So, now we have to address the tougher question: If we find soybean aphids in soybean fields right now, what should we do? The answer to this question is not straightforward.

Update on Corn Rootworm Injury
Our summer research crew has begun to evaluate roots for corn rootworm larval injury at our trial located just south of Urbana. Roots from our experiments are still being rated for injury. We hope to share the preliminary root injury ratings for the various treatments in an upcoming issue of the Bulletin.

To more effectively target where soil insecticides should be used during the spring of 2002, we urge growers to begin final preparations for monitoring their soybean fields with Pherocon AM traps.

Soybean Viruses: Old, New, and Unknown
Although we hear much about fungi and bacteria that cause disease of soybeans, we have not heard as much about viruses that cause soybean diseases--at least not until recently. In contrast to many fungi and bacteria, viruses often cause mild or even hidden effects on soybean.

Much is known about soybean viruses, but much remains unknown, and there are several ongoing research projects in Illinois and neighboring states that will provide new information about these pathogens in the near future.

How Much Is Dryness Hurting Corn and Soybean?
As of July 15, more than 60% of the corn crop in Illinois was silking, and that number will move up quickly with the warm weather, probably to near 90% by this weekend. Even though rainfall since the crop was planted continues to be close to or even above normal in many areas, the recent lack of moisture is starting to take a toll on yield potential in many cornfields.

The soybean crop has also been affected by dryness, though it has a better chance for recovery than does corn that has pollinated.

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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