Farmers in Oregon's Willamette Valley hate slugs, slimy mollusks that munch their way through crops.

But as familiar as farmers are with the mollusks, they acknowledge they're often baffled. And answers to their questions have come, shall we say, sluggishly.

Growers and researchers at a recent Oregon State University "Slug Summit" in Salem agreed that the pests are causing more problems these days. But they have no good explanation why that's so.

And the agricultural publication The Capital Press (http://bit.ly/1xCNiLT) reports that they came down from the summit with an unanswered question: What to do?

Some farmers say the decline of field burning and the rise of reduced-tillage farming in recent decades has left more vegetative shelter for slugs in fields.

But other farmers report persistent slug problems despite tilling heavily and burning fields.

Growers say a crop may sometimes be devastated by slugs despite the use of poison bait, but the same field will do well with the bait in other years,

Slugs that survive one commonly used chemical quickly develop an aversion to it, Oregon State University researcher George Hoffman said.

The summit was told it's unlikely more toxic pesticides will enter the market because of harmful consequences for other species.

Disrupting the pest's reproduction with pheromones or releasing natural predators are viable options, but these measures must be employed in concert to be effective, said Paul Jepson, director of Oregon State's Integrated Plant Protection Center.

"There are plenty of things that eat slugs and really love them. But the problem is they're not sufficient," Jepson said.

Bottom line: More research needed.

But Dan Arp, dean of Oregon State's College of Agricultural Sciences, said that appropriations for extension agents have barely kept up with inflation. The school may be able to establish a slug-fighting position as faculty members retire, or perhaps put together a "strike team" of existing professors and agents, he said.

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Information from: Capital Press, http://www.capitalpress.com/washington