ABERDEEN, Idaho — Researchers with the local potato breeding program harvested a special block of first-year clones on Sept. 29, screened for their ability to help the industry cope with a quarantined pest.

The block contained a half dozen plants from each of 223 breeding clones resulting from crosses of Western Russet and Eden, a round Scottish variety with known resistance to potato cyst nematode.

Material in the block has been screened for the presence of two genetic markers associated with resistance to the microscopic but highly destructive pest. Joe Kuhl, a University of Idaho associate professor of plant genetics, will also use clones from the plot in genetic mapping research to identify new genes associated with PCN resistance.

Kuhl said he’s midway through a five-year project focused on breeding PCN-resistant russets, funded by USDA’s National Institute of Food and Agriculture. Several fields within a 7-mile radius of Bingham and Bonneville counties in Eastern Idaho have been under quarantine since a type of PCN, called pale cyst nematode, was discovered for the first time in the U.S. in 2006. Affected growers have been calling for PCN-resistant russet varieties.

“The idea is to look for that long russet type,” Kuhl said. “That is a huge problem in the U.S. now because the long russet types don’t have good resistance to PCN.”

Louise-Marie Dandurand, director of UI’s pale cyst nematode program, has evaluated the crosses in a greenhouse to determine how they affect the viability of PCN cysts and eggs.

Rich Novy, the USDA Agricultural Research Service breeder who made the crosses for Kuhl’s project, plans to immediately use the best breeding clones from the PCN-resistant population as parents in his program.

Novy explained the Aberdeen staff plants about 125,000 first-year clones each spring, crossed to target a host of industry needs, ranging from high doses of vitamin C and iron to resistance to several diseases.

He makes crosses from about 200 different parents, sourced from throughout the world. For example, he was pleased by crosses made with a late blight-resistant Irish spud, called Slaney, and an Aberdeen breeding clone.

Only about 2 percent of first-year clones are retained. Novy typically plants a single seedling tuber for each first-year variety. In the second year, he plants 12 seeds for each clone. Further on in the evaluation process, clones are tested for processing qualities, yields and performance in Washington and Oregon.

Washington State University agronomist Mark Pavek, who assisted in the field selections, wrote the word “Basin” on the tag of one bag of spuds he saved, explaining his program encourages Aberdeen to keep clones that may appear too skinny for Idaho but could have the ideal shape when grown under Columbia Basin conditions.

Potato industry representatives also help with field selections — and conduct their own parallel evaluations of certain promising clones.

Last season, USDA plant pathologist Jon Whitworth started testing tubers in the breeding program for diseases and viruses — starting with tubers selected from the single-hill trials — to rid the program of disease-susceptible clones.

“We’re selecting in a commercial growing area, so there’s higher virus pressure,” Whitworth said.