07/10/06 Root-lesion nematode and winter wheat

Farm and Ranch July 10, 2006 When researchers at the at the Columbia Basin Agricultural Research Center near Pendleton did soil samples looking for the root-lesion nematode a few years ago, they found the largest populations in spring wheat in annual cropping systems. So they thought spring wheat had the most at risk from the yield robbing nematode, not winter wheat in a summer fallow system. In fact, researchers showed that spring wheat yields in annual crop systems were reduced up to 36 and 60 percent. But plant pathologist Richard Smiley says a scientist from Australia hired this past year, told the Oregon researchers they weren't sampling deep enough in the soil profile. Smiley: "We have then started to adopt his practice of using cores to four or five feet depth and we have found that the peak populations under some of our winter wheat fallow fields that we thought were free of root-lesion nematodes, actually have the peak populations down at two and three foot depth in the profile. And we are finding now that we are finding responses to root-lesion nematodes in our winter wheat as well as the spring wheat." Smiley says the economic threshold is considered to be 900 root-lesion nematodes per pound of soil and at the Pendleton Station they found two-thousand per pound all the way down to the third foot. He says about the only practical way to manage this pest in summer fallow systems is going to be through the development of resistant wheat varieties and genes for resistance have been identified. I'm Bob Hoff and that's the Northwest Farm and Ranch Report on the Northwest Ag Information Network.