Issue No. 17, Article 5/July 16, 2004
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. The regions have been defined broadly to include the agricultural statistics districts as designated by the Illinois Agricultural Statistics Service, with slight modifications:
- North (Northwest and Northeast districts, plus Stark and Marshall counties)
- West-central (West and West Southwest districts, and Peoria, Woodford, Tazewell, Mason, Menard, and Logan counties from the Central district)
- East-central (East and East Southeast districts [except Marion, Clay, Richland, and Lawrence counties], McLean, DeWitt, and Macon counties from the Central district)
- South (Southwest and Southeast districts, and Marion, Clay, Richland, and Lawrence counties from the East Southeast district)
We hope these reports will provide additional benefits for staying current as the season progresses.
Corn in the southern and central area of the region has been tasseling/silking for more than a week. The northern area of the region was not in full tassel as of July 14. Numerous reports have been received concerning rootworm larvae damage in first-year cornfields located in Marshall, Putnam, and Bureau counties. Many of the fields had an insecticide applied at planting or seed-applied. From the reports, it appears larvae feeding on insecticide-treated first-year corn occurred on a wide variety of insecticide products.
Soybean aphids have been a hot topic of discussion during the last week, but from a different perspective. The discussion has focused on individuals scouting soybean fields and having difficulty finding any aphids.
Also, there is some concern about gray leaf spot infestations. Several reports have been received of fungicide-treated cornfields in Bureau County.
Concern in the region quickly shifted from rootworms in first-year and continuous cornfields to gray leaf spot. Reports and rumors pertaining to fungicide applications intended to manage this disease abound. Many question whether this disease can really have an intense areawide impact, with much of the corn crop now only a few weeks from hard dough stage.
In addition to the rectangular lesions associated with gray leaf spot, an abundance of moisture in much of the west-central region has allowed lesions associated with other foliar blights to appear in corn, such as the brown "cigar-shaped" lesions symptomatic of northern corn leaf blight.
Soybean fields continue to show signs of foliar disease, as many suffer from a little too much moisture. Septoria continues to hold its own on the lower part of the plant. In addition to fungal disease, occasional (noneconomic) viruslike symptoms are being encountered while touring bean fields. Root rot observations continue as well.
Still observed at intense levels in various parts of the region are Japanese beetles in corn and bean fields, rootworm beetles in corn (with western corn rootworm variants filtering into beans), grasshoppers well within the borders of cornfields and bean fields, and potato leafhoppers in alfalfa and bean fields.