Tiny Nematode, Big Losses to Eastern Oregon’s Wheat

Root-lesion nematode
Root-lesion nematode

Researchers at Oregon State University have discovered the cause behind $51 million annual losses in the Northwest’s wheat industry. Five times smaller in diameter than a human hair and half a millimeter long, the root-lesion nematode has been found in 90 percent of fields. In 60 percent of fields in Oregon and Washington, it exists in numbers large enough to reduce crop yields.

The trouble is knowing it’s there. This transparent, microscopic nematode lives in the soil and feeds on the roots of wheat, oats, and other crops. This makes it much harder to spot than fungal pathogens that attack both the roots and the crowns of plants—and it paves the way for other pathogens, too.

“There just aren’t apparent visible symptoms in the plant canopy,” said Dick Smiley, a professor of plant pathology at Oregon State University who has studied the nematode since 1999. “It can only be evaluated by testing the soil at a commercial lab or a university lab.”

In areas with less rainfall—such as eastern Oregon—the problem is exacerbated, as the nematode hinders the plants’ ability to take up water.

“It becomes more important as the rainfall diminishes, particularly in fields that cannot be irrigated—which is a great share of the wheat industry in the Pacific Northwest,” said Smiley.

This makes it a huge problem in the part of the state most dependent upon its wheat crop.

“Winter wheat is still the king crop in all of eastern Oregon,” Smiley said. “That is the major crop that is profitable.”

Getting rid of the nematode poses another quandary. While crops such as barley, flax, and safflower are less susceptible, they are also far less profitable, which makes crop rotation an impractical solution. Pesticides aren’t an option, either, as none are legally available to kill the nematodes.

“We do not know of any way to control these nematodes through chemical means in large-scale agriculture,” commented Smiley.

Instead, researchers at Oregon State University are trying to genetically modify the plants for greater resistance.

For now, the root-lesion nematode will remain the hidden ruler of eastern Oregon’s king crop—until that crop’s genome is changed enough to resist a very stubborn pest.

By Jen Matteis