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No. 07/May 10, 2002

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Wet Weather, Delayed Planting, and Insects
The weather may have a dramatic impact on the potential for insect problems. The cool, wet soils and delayed planting may represent either bad news or good news, depending on the crop and the insect. This article includes an overview of how our current spring weather conditions may affect the potential for certain insect pests to cause problems (or not).

Watch for Armyworm and Black Cutworm Larvae in Any Fields That Have Been Planted
At this time, with corn still to be planted in many areas, it's almost an overstatement to suggest that people should watch for armyworms and black cutworms as soon as corn seedlings emerge. Both species will be large enough to cause noticeable injury to corn seedlings very soon. Numbers of armyworm larvae encountered thus far have been small. However, after some recent heavy flights of armyworm moths, the numbers of larvae could increase in some areas.

Southern Corn Leaf Beetles Are Right on Schedule
The southern corn leaf beetle has become troublesome in several states in the Midwest during the past few years, after having gone virtually unnoticed for decades. This article includes information from a classic article and from field observations during the past few years. Here the following questions are addressed:

What do southern corn leaf beetle adults look like, and where should I look for them?
What does injury caused by southern corn leaf beetles look like?
What types of fields are most susceptible to damage caused by southern corn leaf beetles?
How did southern corn leaf beetles get into my field, and what happens after they get there?
When is control of southern corn leaf beetles justified?

When Will Rootworm Larvae Hatch?
It's unlikely that we will experience an early hatch of rootworm larvae from overwintering eggs this year. It's possible that the soggy soil conditions will have a negative impact on rootworm larvae when they do hatch. Let's keep our fingers crossed.

Controlling Bean Leaf Beetles
Although it seems a bit silly to be talking about insecticides for control of bean leaf beetles, at least a few fields of soybeans have been planted. Consequently, they will be at risk when bean leaf beetles find them. The beetles don't have much to choose from right now, so any seedling soybeans will have to do.

Alfalfa Weevil Report
People in southern and central Illinois have experienced some of the heaviest infestations of alfalfa weevils they have witnessed in many years. The defoliation caused by the larvae has been excessive. Wet weather has hampered control with insecticides and, in some instances, reduced the efficacy of an insecticide after it had been applied.

Degree Days, Phenology Models, and Insects
If you are interested in learning more about degree-days and phenology models, I encourage you to visit the Web site created by the University of California Statewide Integrated Pest Management Project. In addition to excellent explanations of degree-days and phenology models, this Web site includes a huge amount of information on the use of these tools for management of many insect pests, as well as some other pests, some beneficial insects and mites, and crops.

Curly Wheat: An Exercise in Troubleshooting
Some very odd leaf symptoms have been showing up in winter wheat fields in south-central Illinois. Upper leaves on affected plants are curly. The curl is reminiscent of curling ribbon or an unfurling wood shaving. So naturally this unusual symptom begs the question, "What is it?"

This question has strained our troubleshooting skills. The article discusses such possibilities as WSMV, herbicide damage, a genetic tendency, the Russian wheat aphid, and environmental factors.

Chances of Stewart's Wilt of Corn Increased After Warm Winter
One of the potential impacts of the warm winter of 2001-2002 is an increased chance of Stewart's bacterial wilt of corn this summer. This disease is primarily a problem on susceptible inbreds and sweet corn; however, some hybrids with low levels of resistance or other hybrids may also be affected when corn flea beetle populations are very high.

Based on the predictions, scouting efforts should be intensified to identify problems with Stewart's wilt this spring and summer. Preventative management with resistance and seed treatment insecticides are the keys for reducing problems with Stewart's wilt.

Watch for Stripe Rust of Wheat in Illinois
Stripe rust of wheat may show up in Illinois this year unless the weather becomes and stays hot or dry. This article includes a description of symptoms and suggestions for management.

Results on Herbicide Resistance in Illinois
During the last 20 years we have confirmed nine different herbicide-resistant weed biotypes in Illinois. We have been able to keep fairly good records on where, when, and how widespread the herbicide-resistance problem is. This article includes an extensive list of confirmed herbicide-resistant weed biotypes in Illinois. However, like most other problems in agriculture, herbicide resistance has continued to spread throughout the state.

Rain Delay 2002--Holding On
Despite what things look like, the rains will end and it will dry off so that planting can resume. How long that will take is a guess, but history tells us it will happen.

This article discusses management changes might be considered in an attempt to improve chances for better yields of late-planted corn.

Wheat Crop Holding Its Own, So Far
While the winter and spring have been relatively kind to the wheat crop, the wet weather in recent weeks has not been helpful. We have not seen extensive disease problems yet, but rainfall during flowering provides ideal conditions for Fusarium head blight to develop. Leaf disease may not be far behind.

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, and west-central Illinois.

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

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