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No. 06/May 04, 2001

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Southern Corn Leaf Beetle Sightings Continue
Observations from the field this spring suggest that the southern corn leaf beetle is here to stay. So far, injury has not been too heavy. But the message seems clear--don't hesitate to begin scouting for these insects; they are very difficult to find. Producers are strongly encouraged to keep their eyes open for southern corn leaf beetles in any cornfield where seedlings are beginning to emerge.

The answers in this article are intended to shed some light on many of the questions we've received concerning southern corn leaf beetles. They include the following:

Why are southern corn leaf beetles so difficult to find?
How do southern corn leaf beetles injure plants?
Are some cornfields at greater risk to injury by southern corn leaf beetles?
Where do southern corn leaf beetles overwinter?
What other information is available concerning the life cycle of southern corn leaf beetles?
Is there an established economic threshold for southern corn leaf beetles?
Are there any products labeled for use as rescue treatments against southern corn leaf beetle injury?

More Reports of Black Cutworm Moth Captures
To date, reports of black cutworm injury have been very sporadic and light. As more corn emerges, reports of injury may increase. We are continuing to receive information concerning the capture of moths in pheromone traps.

Growers are encouraged to remain vigilant, especially until cornfields develop beyond the 4-leaf stage of development. Cutting could begin in some areas of central Illinois as early as May 8. Producers are advised to look for signs of leaf feeding and cutting and be ready to apply rescue treatments as required.

First Capture of European Corn Borer Moth Reported in Southern Illinois
This year's capture suggests that we are slightly ahead of last season's pace with respect to European corn borer emergence. Based on estimates of the overwintering population of borers, we don't anticipate a widespread economic threat from the first generation of European corn borers. However, the second generation of this insect pest could surge ahead later this year.

Cereal Leaf Beetles Observed in Wheat Fields
Cereal leaf beetle larvae can be found in low-to-moderate densities in southern Illinois wheat fields. This article describes of the insect and discusses the potential for yield loss.

Armyworms in Wheat: Recommended Scouting Procedures and Thresholds
In recent days, we've received reports of impressive densities of armyworms in wheat fields in some areas of Kentucky and Tennessee. This suggests that wheat producers in nearby areas of southern Illinois should begin to monitor their wheat fields for potential armyworm injury.

This article describes the injury caused by armyworms, offers scouting tips, and discusses options for control.

Alfalfa Weevil: Degree-Day Accumulation Update
Growers in southern Illinois have by now dealt with weevils for several weeks. The optimum date for harvesting alfalfa in the southern one-third of the state is at hand. Projected degree-day accumulations indicate that by May 13, alfalfa growers, even in the most northern counties of Illinois, should begin to see evidence of alfalfa weevil feeding.

Seedling Blights Caused by Pythium spp.
One of the most common and earliest groups of fungi that attack corn and soybeans belongs to the genera Pythium. This article describes the damage caused by Pythium fungi in corn and soybeans and offers suggestions for management.

Recognizing Potential Nematode Problems on Corn
Corn nematode damage may become evident 2 to 4 weeks after seedling emergence but is most pronounced in late May and June. Because nematodes can damage corn without showing aboveground symptoms, they may be overlooked.

The use of crop rotations or nematicides will be of little value for corn already planted. However, an awareness of corn nematode problems is essential for planning control strategies for the next growing season.

Dry Soils and Soil-Applied Herbicides
Herbicide effectiveness can be significantly reduced when a soil-applied herbicide is sprayed on a dry soil surface with no incorporation (mechanical or by precipitation) for several days following application. This article discusses how much rainfall is required to move the herbicide into the soil and how soon after application the precipitation is needed.

Several postemergence herbicides for grass control in corn are described, including Basis 75WDG, Basis Gold 89.46WDG, Accent Gold 83.8WDG, Steadfast 75WDG, Accent 75WDG, Celebrity Plus 70WDG, Beacon 75WDG, NorthStar 47.4WDG, Spirit 57WDG, and atrazine.

Early-Season Weed Control in Corn
In many cases, with the push to get all of the corn crop planted and the extreme winds that have plagued us over the last few weeks, it has been very difficult to get soil-applied herbicides sprayed in a timely fashion. This has left many growers and applicators with the decision on what to do for weed-management strategies on those acres that haven't been treated and the corn crop has emerged.

This article describes two different approaches a grower could take in this situation. The first option is to use the soil-applied herbicide program that was initially planned, and the second option is to switch to a total postemergence strategy.

Increasing Your Knowledge About Smartweeds (Polygonaceae Family)
Some of the very first weed species that emerged this spring and many springs in the past belong to the smartweed (Polygonaceae) family. This brief review of the Polygonum species commonly found in Illinois may prove to be beneficial in the identification and subsequent control of these species.

The article discusses prostrate knotweed, Pennsylvania smartweed , ladysthumb, wild buckwheat, swamp smartweed , curly dock, red sorrel, and Japanese knotweed.

Waterhemp Management in Corn and Soybeans
In the last edition of the Bulletin, we described the identification and biology of waterhemp and touched briefly on several management considerations. This article examines, in more depth, waterhemp-management options for corn and soybean production systems.

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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