Sunday, June 7, 2015

Have you Seen Slugs in Your Corn and Soybeans?

Some recent field visits within the Burrus footprint have shown indications of slug damage to soybean and corn fields. Slugs are very delicate animals that can desiccate rather easily. They actually are little more than moist flesh folded over itself. 
Moisture and cool temperatures are therefore essential for slug populations to thrive.  Temperatures ranging from the 60s to the 70s with high relative humidity create the ideal environment for these members of the mollusk family. The need for moist conditions also explains why slugs prefer fields with abundant residue. Residue provides a moist microenvironment which once again allows adult slugs and their eggs to persist. 
Slugs grind long streaks or holes in leaf tissue giving that tissue a “ragged” appearance. They are usually deemed the culprit because they leave slime trails on ragged plants and on the ground surrounding ragged plants.

Wlug feeding on corn in Southern Wisconsin,  Brad Kufalk, Hughes Seed
Slug trails on corn in Missouri, Seth Link, Burrus Sales Manager

Slug feeding on lower leaves in Missouri not a major problem on lower leaves, Seth Link, Burrus Sales Manager
If soil moisture keeps seed slots open, this may allow high slug populations to inflict more stand-reducing injury, especially in young emerging corn and soybeans.  Slugs do their damage with a tongue-like appendage that is very abrasive. Slugs may be able to reach the seed and/or growing point. Both are usually below ground with the growing point, moving above ground only later. 

Slug feeding found on soybeans in Central Illinois, Evan Weyant, Burrus Intern
Slugs found at dusk in Central Illinois, Stephanie Porter, Burrus Sales Agronomist

The heat should stop slugs.  When conditions become unfavorable, many slugs will die and others will go into an inactive state. 

Where stand reduction does occur and a replant is necessary due to slug damage, consider disking the field before planting to disturb environmental conditions that promote slug injury. Pesticide options are available and may provide one more avenue to reduce slug pressure when corn is replanted. There is some evidence that seed treatments such as PowerShield® help deter slugs from damaging the seed.

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