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No. 08/May 15, 2003

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Bean Leaf Beetles: To Spray or Not to Spray?
If you haven't done it already, schedule scouting trips to fields where soybean seedlings have emerged and are growing. Apparently growers are anxious about bean pod mottle virus, but we have little verification of its prevalence in Illinois soybeans last year. We urge careful assessment this year before you decide an insecticide is warranted.

Update on Heat Unit Accumulations for Corn Rootworm Larval Hatch
Though it's too early to accurately predict severity of corn rootworm problems this season, several factors could contribute to management challenges. We'll let you know when the larval hatch has been confirmed.

Update on Stalk Borer Development and Management Tips
Stalk borer larvae begin to hatch usually in late April and early May; corn growers in the southern tip of Illinois should begin scouting in the next week. Good management begins with sound weed management practices. Suggested insecticides and economic thresholds are presented here.

Quick Tidbits on Insects
Cornfields should be scouted for early black cutworm injury. For alfalfa weevils, little more than pinhole feeding has been reported, but control may be warranted in particular circumstances. Potato leafhopper activity is beginning, though the pest is not currently a threat.

What's the Scoop on Soybean Seed and Seedling Diseases in Illinois?
This topic produces more questions than any other single disease issue on any crop in Illinois. Described here are soybean seed and seedling diseases, their characteristics and conditions that favor them, and approaches to managing them.

Corn Nematodes in Illinois
Nematodes are often the last cause considered for problems with corn development. The only way to diagnose nematode problems in corn is through analysis of soil samples by a qualified lab. Because control depends on the species involved, a reliable diagnosis is critical.

Rainbows in the Fields
Winter annuals are flowering in many fields because of delays in both planting and weed control measures. Recommendations are offered for several scenarios: no herbicide applied, crop not planted; no herbicide applied, corn has been planted; herbicide applied, crop not planted; herbicide applied, crop has been planted; a change in the hybrid to be planted.

Plant Spacing Uniformity
It's a good time to look at corn stands in many parts of Illinois. The results of recent research on plant spacing uniformity might be summarized this way: Within reason, if a planter is dropping the desired number of seeds per acre with good depth control and adequate seed covering, plant spacing variability is costing little or no yield loss in corn.

Regional Reports
Reports are provided this issue for northern, southern, and west-central Illinois.

More Details on Corn Nematodes
It is time to reassess the impact of corn nematodes on production and determine whether R&D efforts are what they should be, given the current value of yield losses and expected increases. Corn breeders should be in the vanguard of this reassessment, because resistance or tolerance will be the best weapon for fighting losses. Nematode species are detailed, with images provided.

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

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