Slug Management Case Study

Mika J. Hunter
Decision Case Study-
Agroecology Internship 2003

Farm Description
Cedar Meadow Farm is located in Lancaster County, Pennsylvania. Lancaster County is characterized by very hilly farmland. The major management techniques used on Cedar Meadow Farm are no-till and permanent cover cropping. Permanent cover cropping involves maintaining a living crop in the soil at all times. In addition, cover crops act as a source of organic residue that covers the soil.

Spring 2003 Weather
The weather of this spring was characterized by a long period of unseasonably cool and rainy weather.

Identification of Slug Problem
Slug damage was identified on emerging corn plants. This damaged is characterized by holes ‘chewed’ in plant vegetation and trails of slug slime on plants and soil. Slugs were observed at night feeding on plant material.

Management Options
A consistent option for slug control is to disperse a pesticide on a bait item. Pellets containing material that acts as an attractant to slugs is combined with a pesticide. Most spray pesticides are not effective because they fail to cause consistent slug mortality. Slug problems are greatest when the soil remains in large aggregates, which act as shelter. Finely tilled or compacted soil reduces the amount of shelter available to slugs. Field settings that are free of weeds, stones, and other debris help contribute to a reduced slug problem, by eliminating shelter. Field systems containing residual organic matter contribute to slug problems. Reduced tillage and mulching practices worsen slug problems. Another method that has been used to control slugs is applying liquid nitrogen fertilizer to fields. On direct contact, liquid nitrogen will damage and/or kill a slug. This method of control is most effective when the nitrogen is applied at night, when slugs are most active. The crops might show superficial damage in the form of ‘burned’ looking vegetation when the spray is applied. This method has an added benefit of adding nitrogen to the soil while controlling pests.

Method of Control Employed at Cedar Meadow Farm
Initially, slug bait pellets were applied to fields where slug damage was evident. Due to excessive rain, many of the pellets were washed away. Liquid nitrogen was sprayed on many cornfields and did show positive results. In fields where there remained living cover crops at the time of corn planting as much living material was left between each row in order to provide alternative food for the slugs. This method was very effective.