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No. 04/April 20, 2001

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IN THIS ISSUE:
Corrections
In the print version of issue no. 2 a Web address was printed incorrectly. The correct address is provided here.

The caption used with the corn flea beetle map in the printed version of issue no. 3 was incorrect. The correct caption is provided.

Black Cutworm Migration Update
Captures of black cutworm moths continue in many areas of the state; sporadic reports of intense captures have also been received. This article answers the following questions:

What fields are most at risk in developing economic infestations of black cutworms?
Are certain weeds more attractive to black cutworm moths?
How do delays in planting and tillage affect the potential for cutworm damage?

Using Pheromone Traps to Monitor Flights of Moths
Several people around the state use pheromone traps to monitor for different species of moths to detect the occurrence of early-season flights to aid in predicting their development. The sex pheromone lure for each species is supposed to be very specific, enticing the males of only one species. However, occasionally other species of moths are captured in traps that contain lures that are not supposed to attract them.

This article discusses what to do if you begin finding more than an "accidental" number of another species in your traps.

Early-Season Insect Pests of Corn
It's not too early to remind people to begin watching for a slew of insects that attack corn early in the season. These include grape colaspis, seedcorn maggots, white grubs, and wireworms, which work underground, and billbugs, southern corn leaf beetles, and stink bugs, which feed on plant parts above ground and cause characteristic feeding injury.

It is very important to diagnose an insect problem accurately if any control tactics are to be considered.

Status of Alfalfa Weevil Development
The recent cool weather slowed the development of alfalfa weevils, but it didn't stop them. Significant damage caused by alfalfa weevil larvae has been observed in Randolph County.

Experience thus far in southern counties suggests that alfalfa growers need to be very alert for alfalfa weevils right now. Assuming we are mostly done with cool temperatures, the larvae will start developing rapidly.

Some discolored alfalfa weevil larvae have been observed, which may represent the beginning of a disease epizootic in some fields.

Winter Wheat Disease--Good News Update
This time last year we were in the midstages of a serious epidemic of wheat streak mosaic virus (WSMV), transmitted by the wheat curl mite. This year the crop appears to be in excellent health.

This article describes the barley yellow dwarf virus and the soilborne wheat mosaic virus, including a discussion of life cycle, management, and diagnosis.

Sclerotinia Crown and Stem Rot of Alfalfa May Be a Problem in Some Fields
This is the time of the year when the effects of Sclerotinia crown and stem rot are often noticed in Illinois alfalfa fields. This disease is most common in the southern half of Illinois. Sclerotinia crown and stem rot may be noticed as death of plants in large or small patches. The disease is typically most destructive in fall-seeded stands, where large patches of the young plants can be killed.

This article discusses the symptoms of the disease and provides suggestions for management.

A Review of Early-Season Weed Species
No-till fields are rapidly "greening" from the growth of winter and early-summer annual weed species. This article provides a brief review of several of these species for those attempting to identify what's currently growing in the fields, including henbit, purple deadnettle, mustards, butterweed , chickweed, horseweed, star-of-Bethlehem, pineapple-weed, kochia, dandelion, and buttercup.

Valor Registered for Soybeans
Valor 51WDG (flumioxazin) recently received a label for use in soybeans.

The mode of action of Valor is similar to the herbicide Authority (sulfentrazone), and the two herbicides have very similar weed control spectrums. This article discusses some of the differences between these two herbicides.

Weed Emergence Sequences
This article discusses the Weed Emergence Sequences bulletin, available on the Web. This bulletin helps focus our attention on emergence sequences of different weed species throughout the growing season and the duration of their emergence. It can also be used as an identification guide of 16 common weed species in the Midwest. Each weed species is characterized by an emergence date relative to growing degree-days (GDD) as well as the length of time (weeks) each species emerges.

Cold Weather and Crops
The drop in temperatures to below freezing on April 17 and 18 raises questions about freeze injury on crops that are in the field. With the warm temperatures early in April, the wheat crop has grown rapidly, almost catching up to its normal stage of growth, following cool temperatures and slow growth in March. The greatest concern over freeze injury is in those fields with the most advanced growth.

This article describes damage due to cold temperatures and provides recommendations for the near future.

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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