Slugs in Soybeans
Crop Damage: Two main groups of slugs (Deroceras spp. and Arion spp.) have been identified as soybean pests the U.S., Canada, and Mexico. Gray garden slugs (Deroceras reticulatum) are often associated with damage to soybean seeds and seedlings. Stand loss occurs when slugs destroy seeds, hypocotyls, or cotyledons. Feeding causes ragged holes on unifoliate and trifoliate leaves.
Pest Description: Slugs are not insects. They belong to same class as snails, but lack shells. Slugs are ¼ to 2 inches long with soft, gray to gray-brown bodies. They have four tentacle-like appendages on the head. Slugs produce slime and use a specialized muscle to glide along surfaces. This slime trail can help confirm the presence of slugs.
Gray garden slug.
Joseph Berger, Bugwood.org
Slug on leaf.
Laura Iles, Iowa State University
Scouting: There are no established sampling or management protocols for slugs in soybean. Gray garden slugs are most commonly a problem in late planted fields and fields with high levels of organic residue, including no-tillage or reduced tillage fields and fields with cover crops. Slugs are more prevalent in cool, wet environments. Because slugs are active at night, scouting should occur at dusk or in the early evenings in areas with poor emergence or dead plants. Examine the soil surface, sift through soil and crop residue, and search for slime trails on nearby plants. If slugs are present, scout the entire field.
Management: No rescue treatments are available for slugs in soybean. If replanting is necessary, consider tillage practices to reduce residue. Plant when seeds can quickly emerge and reach growth stage V2 to minimize slug impact. Insecticides are ineffective against slugs.
Developed and reviewed by Carol Pilcher, Iowa State University and Robert Wright, University of Nebraska-Lincoln, with support from the United Soybean Board.
Slug on a leaf. Photo by Laura Iles, Iowa State University.
Gray garden slug on a grass blade. Photo by Joseph Berger, Bugwood.org.
Gallery images courtesy Laura Iles, Iowa State University and Joseph Berger, Bugwood.org.
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