He is investigating the gray garden slug and its effects on the grass seed industry in the Willamette Valley. These voracious molluscs cause significant damage to newly planted grass seed and wheat fields in western Oregon, costing growers millions of dollars in lost yields, replanting and pest control. Gray garden slugs are also a common garden pest west of the Cascades. The gray garden slug is native to Europe and Asia. It spends most of its time underground in the soil, especially in the heat of the summer.
Slugs come to the surface at night to feed on grass seeds, rootlets and young seedlings.
We find up to 40 slugs in one crown of perennial ryegrass. Studies have shown that in the summer, only 5 percent of the slug population is above ground at any one time. The rest are underground digesting food, laying eggs and feeding on rootlets and endosperm of seeds. Grass and wheat farmers lose acres of seedlings to these slugs. One mature slug can take out five to 10 wheat seeds in a night.