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Northern Illinois Agriculture

University of Illinois Extension

Another snow day!

Posted by Russel Higgins - Weather

An evening snow storm that dropped an additional 4 to 7+ inches of snow over most of northern Illinois again caused the cancellation of many schools and activities in northern Illinois. As I watch the icicles forming on my office grow to almost stalactite size I again have been searching for an agricultural silver lining in the weather we have been experiencing. The (at times) sub zero weather could certainly have an effect on insect pests that overwinter as adults. For corn and soybean producers that narrows down to a very short list. Bean leaf beetles, which by and large have not been an issue in northern Illinois in recent years. Our greatest insect pest concern, the rootworm beetles, are overwintering as eggs at varying depths in the soil profile.

In recent weeks there have been several articles speculating on winter weather effects on the rootworm egg population. Here is my take, (the way I look at it, no matter what my prediction, I can only improve after selecting Denver to win the Super Bowl!)

Dr. Mike Gray, University of Illinois Extension entomologist looked at rootworm winter survivability while at Iowa State University. Gray along with Jon Tollefson conducted the study during the winters of 1983-1985 which were uncharacteristically cold and had limited snow cover. The study examined the influence of different tillage methods and winter weather on rootworm egg survival.

From this study Dr. Marlin Rice (former Iowa State Entomologist) gave the following summary;

If a rootworm population reduction was to occur, then three conditions would have to be met:

  1. severe cold
  2. absence of an insulating snow cover, and
  3. para-plow or mold-board tillage in the field.
Dr. Rice went on to suggest "I would anticipate that fields that were plowed will have greatly reduced populations of corn rootworms, whereas fields with minimum tillage or no tillage should not expect a significant reduction in rootworms." While these suggestions were made in Iowa I would expect them to be true for northern Illinois as well. The full ISU Integrated Crop Management article authored by Dr. Rice can be accessed here.

Rootworms will be addressed in both upcoming Extension meetings in Northern Illinois

Northern Illinois Crop Management Conference February 12th & 13th, Kishwaukee College

Rootworm management and biology meeting February 19th, 9:30 - Noon, Northern Illinois Agronomy Research Center

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