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College of Food, Agricultural, and Environmental Sciences


Slugs Feasting on Slow-Growing Crops

June 2, 2003

WOOSTER, Ohio€” Continued cool temperatures and moist conditions have slowed down crop growth enough that gray garden slugs are beginning to make a meal of no-till corn and soybeans. Some growers throughout east and east central Ohio are being forced to replant their soybean crop partly due to the pest€™s contributions. €œWe have had lousy growing conditions and there are many things that can cause poor stands. Slugs are just one of those causes,€ said Ron Hammond, an Ohio State University entomologist with the Ohio Agricultural Research and Development Center. We are at the point in time where slugs have hatched or are hatching and becoming more numerous in fields. We are starting to get reports from growers and consultants that certain fields need to be treated. Hammond, a professor in the Department of Entomology, said that monitoring over the next two to four weeks should reveal how serious of a problem slug feeding will become. The best thing growers can do now is to scout fields with a history of slug problems and determine whether or not treatment is warranted. €œWe have two situations that are contributing to slug feeding,€ said Hammond. €œOne problem is that a lot of the crops got planted in late April, but the weather has been so cool and wet that the crops aren€™t growing and they are unable to outgrow any slug damage. The other problem is that because of the weather, remaining soybean plants may be planted late. In those fields where slugs are present, they are just sitting there, getting bigger, waiting for their next meal.” The juvenile stage of the slug creates the most damage to crops, and its voracious appetite and large densities can be devastating for farmers who have had a history of slug problems. Upon hatching in early to mid-May, the slug will begin feeding on anything that is planted in the field, whether it€™s corn, soybeans or alfalfa. Slug feeding can cause significant reductions in corn yields and total stand loss in soybeans. Growers who have had a history of slug problems should keep a close eye on their fields when the weather begins warming up. Finding two to four slugs per trap could indicate a potential problem and top priority should be given to those fields in regards to treatment options. With corn its a defoliation issue and if feeding is heavy enough, slugs can take the corn out, said Hammond. With soybeans you start seeing defoliation on the leaves, but if slugs are heavily active they can take the plant out before you even see it. Ohio State and U.S. Department of Agriculture researchers plan to conduct studies on alternative slug control methods: everything from at-planting-time treatments to tillage practices that still meet no-till requirements to testing the relationship between slug populations and soil pH.

Candace Pollock
Ron Hammond