TWIN FALLS • A bacterium that agriculture officials say could devastate Idaho’s potato crop has been found in a Twin Falls County farmer’s field.
Tests at the University of Idaho showed positive results for Liberibacter, the bacterium that causes zebra chip, said Erik Wenninger, assistant professor of entomology for the University of Idaho’s Kimberly Research and Extension Center.
The substance was found on adult psyllids adhering to a sticky card put in a commercial plot as part of testing for potential diseases in 14 south-central Idaho fields. Wenninger posted a warning to farmers and others Monday on the Pacific Northwest Pest Alert Network.
“The presence of zebra chip in the region has the potential to be economically devastating,” Wenninger and colleague Nora Olsen wrote in a report published by the Oregon State University Extension Service.
Wenninger emphasized that the positive test is a “tentative confirmation.” Another test is being conducted this week to see if similar results are found.
“It would be awfully surprising to have it come back negative,” Wenninger said, adding that officials are proceeding cautiously at this point.
“I don’t want to get people panicked, but I also don’t want to withhold information,” he said.
Wenninger suggests that farmers intensify their monitoring programs for the zebra chip pathogen. Samples can be taken to the Research and Extension Center in Kimberly for confirmation.
Zebra chip causes flecking in potatoes’ flesh. When affected potatoes are fried, there is severe darkening of the chip or fry, according to the OSU article. The defect is severe enough that there’s concern for fresh and process potatoes, it said.
“The disease has been very costly to manage in potato crops and has caused millions of dollars in losses in the southwest U.S., particularly Texas,” according to the article.
The solution in areas where zebra chip is a problem involves season-long, weekly insecticide applications.
Wenninger noted that psyllids have been in Idaho for decades. However, it wasn’t until late in the 2011 growing season that the bacterium for zebra chip was found in low levels in Idaho, Oregon and Washington.
The bacterium was present in Twin Falls and Jerome counties and the Treasure Valley, but not in eastern Idaho, Wenninger said.
“If concentrations are heavy enough, you can definitely see damage during the (growing) season on the above-ground portion of the plants,” he said.
This week’s follow-up tests of Magic Valley psyllids are being conducted by Alex Karasev in his University of Idaho lab. Wenninger said results could be available by Friday.