Finding nematodes

Pacific Northwest soils are chock-full of eel-shaped roundworms so small they’re invisible to the naked eye. Known as nematodes, most of these tiny organisms are beneficial to agriculture because they help decompose organic matter. But a handful are downright destructive, feeding on the roots of wheat, barley, and other crops, and causing more than $50 million in losses in the Pacific Northwest each year.

Leading the way to alert and educate farmers about harmful nematodes is OSU researcher Richard Smiley, who has studied these pests since the late 1990s. Many farmers are unaware that their soils have nematodes; they spread easily, hitchhiking to new locations via the wind, animals, farm equipment, and boots. Smiley has traveled the region testing thousands of plots and documenting the presence of nematodes in 90 percent of soils he’s sampled, and he has spread the latest information to help growers avoid the worst of these microscopic parasites.

[caption caption="Spring wheat roots lightly (left) and heavily (right) affected by nematodes. (Photo by Dick Smiley.)"][/caption]

Farmers are taught to spot telltale signs of the pests’ presence (remember, they’re thinner than a human hair) like stunted crops or yellowed leaves. Applying extra fertilizer, watering strategically, rotating crops on a strict schedule, and planting the least sensitive varieties can stunt the worms’ reproduction and reduce damage. It’s impossible to eradicate the nematodes once they’re established, and since there are no chemicals available for killing them on large wheat fields, OSU’s research-based advice is often growers’ first and last line of defense against these pests.

Smiley has tested hundreds of wheat, barley, and oat cultivars to determine how badly yields are affected by nematodes. This research helps farmers choose which varieties to plant, while crop breeders around the PNW are busy crafting new varieties they hope will free growers from the nematode nuisance.