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Slugs, Anyone?

April 5, 2002
Not being able to wait for corn to be planted in his area, Matt Montgomery, Sangamon/Menard Extension unit educator in crop systems, has already been out looking for critters lurking in fields that will be planted to crops. In a long-term no-till field in Sangamon County, Matt discovered lots of slugs. We usually don't get overly concerned about slugs in Illinois, but the mild winter and recent wet weather may have set us up for some early-season problems. At least it's worth some attention.

According to the ESA's Handbook of Corn Insects (published in 1999), slugs overwinter as both eggs and adults, and their survival is dependent on the severity of winter conditions (i.e., they survive better when winter conditions are mild). Slugs are particularly problematic in no-till situations; their population densities increase when residues are abundant on undisturbed soil surfaces. Crop injury is most severe in the spring when growing conditions are cool and wet. Injury is particularly bad when seed furrows do not close completely, allowing slugs to injure both seeds and seedlings.

If spring weather remains wet and cool, we'll have to watch for slugs as the seedlings grow. You'll know slugs when you see themthey're shiny and slimy, ranging from gray to pale cream with a light mottled pattern. They are capable of causing stand loss if infestations are heavy.

Slugs from Sangamon County. (Photos courtesy of Matt Montgomery.)

There's really no reason to do anything to try to prevent slug damage, but no-tillers may be wise to be prepared. Deadline Bullets (a toxic bait with metaldehyde as the active ingredient) can be applied to field crops (cereal grains, corn, legumes) to control slugs.--Kevin Steffey

Author: Kevin Steffey

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

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