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No. 11/June 05, 2003

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Suddenly, Grape Colaspis
Several reports of grape colaspis larvae feeding in cornfields have been received, mostly from western and west-central Illinois. Injury to larger plants probably will not result in yield loss; however, injury to smaller plants could be more problematic.

Grape Colaspis: Some Background
Though grape colaspis has been written about for more than a century, concern about the pest in central Illinois is only recent. This article reviews grape colaspis history and life cycle, the effect of soil moisture on larvae, and anticipation and management.

Soybean Aphids on Seedling Soybeans
An early sighting of soybean aphids provides a heads-up for everyone presently scouting soybeans. Populations develop more readily when temperatures are cool, and yield losses are usually more significant when soybean aphids colonize seedling soybeans rather than older plants.

Asana XL Labeled for Control of Soybean Aphid
Details are provided for using Asana XL for control of the soybean aphid in soybeans.

Reports of European Corn Borers Begin
Reports of European corn borer moths are being received from around the state. Early-planted fields are at a higher risk than fields planted later in the season. Scouting for larvae and whorl feeding should take place as corn plants approach 15 to 18 inches in height. Scouting directions and a management worksheet to guide control decisions are provided, along with information on life cycle, biology, and suggested insecticides.

Confirmation of Corn Rootworm Hatch
Entolomogists at Purdue University have confirmed the presence of first-instar western corn rootworm larvae in root tissue of corn plants. Reports of any control problems are invited.

Corn Size Limits with Postemergence Herbicides
The likelihood of corn injury may increase dramatically if postemergence- herbicide label restrictions are not followed regarding maximum corn size or development stage for broadcast applications. Follow the most restrictive corn stage (height or leaf collar) listed on the product label. Any cornfields treated within a few days before or after recent cold temperatures should be scouted carefully, as herbicide injury may be accentuated.

Stripe Rust of Wheat in Illinois
Stripe rust of wheat is typically uncommon in Illinois, but this year's cool and moist weather has favored its development. Characteristics and development of stripe rust are described here. Though stripe rust can be managed with fungicides, it is too late for application in many Illinois wheat fields.

Thinking About Crop Stress
Are crops presently under stress? The answer isn't necessarily what seems intuitive. Many fields are in reasonable health, but others may be struggling to become established. Leaf-wrapping, a widespread problem this season, is described.

Regional Reports
Reports are provided this issue for northern and west-central Illinois.

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

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