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Issue No. 11/June 4, 2004

Sporadic Armyworm Infestations Reported in Wheat
Late last week, armyworms were reported in northern Menard County at levels that ranged from two to eight larvae per foot of row, reaching levels at which producers should consider a rescue. In addition, wheat growers need to pay particular attention to the threat of head cutting. But keep in mind that armyworms are very susceptible to a number of natural enemies that include parasitoids and diseases.

Stink Bug Injury in Corn
Significant injury caused by stink bugs was reported, with several areas of infected fields having injury damage levels approaching 20%. Thresholds for stink bugs in corn have not been developed; insecticides recommended for control are listed.

Corn Rootworm Hatch Confirmed
One lone rootworm larva was located in a corn-on-corn field, in southwestern Lee County (northeast of Walnut). Current degree-day totals (base 52?F, 4-inch soil temperature), from January 1 to June 1, indicate that much of the state should be experiencing corn rootworm hatch.

Soybean Aphids Found on Common Buckthorn in Columbia, Missouri
The plants were located about 1/2 to 1 mile from soybean experimental plots and 3 to 5 miles from commercial soybean fields.

Update on Fusarium Head Blight (Scab) and Other Diseases of Wheat in Illinois
Diseases continue to appear in Illinois wheat fields, with Fusarium head blight, also called scab, perhaps the biggest problem in many fields at this time. By general reports, FHB is more common in the northern half of Illinois than the southern half this year.

Musings About Postemergence Herbicide Programs
Outlines historical changes in weed management practices and reviews some of the principles governing the effectiveness of postemergence herbicides, discussing topics such as How long should I wait to spray? What happens when the postemergence application is delayed? Development of herbicide-resistent weed biotypes.

Do You Need to Replant?
Despite almost every location in Illinois reporting above-normal rainfall for the month of May, planting progress for both corn and soybean was much better this year than last, and much of the corn is large enough that damage from excessive water is less severe. Soybean has been hurt by water and hail much worse than corn--due to its later planting, earlier development stage, and growth habit; some fields, and parts of some fields, will need to be replanted or repair-planted.

Regional Reports
A report is provided for northern Illinois this week.