TWIN FALLS • Two more samples from Twin Falls County farm fields have tested positive for the bacterium that causes zebra chip, a disease that damages potatoes by causing flecking in their flesh.
Zebra chip reached severe levels in the Southwest, resulting in millions of dollars worth of crop loss.
The first potato psyllid sample to test positive here was found June 19 in a grower’s field. Samples taken the following week from the same field and the Kimberly Research and Extension Center also contained the bacterium known as liberibacter.
A few more adult potato psyllids collected July 3 were found in two other commercial fields in Twin Falls County and are being tested for liberibacter this week, according to an update on the Pacific Northwest Pest Alert website.
Erik Wenninger, an entomologist with the University of Idaho’s Kimberly center, urged growers not to be unduly alarmed.
“We don’t want people to panic,” he said. “We definitely want people to be aware of this issue. They should stay vigilant and keep a close eye on what is going on in their fields.”
So far, the adult psyllids that could carry liberibacter were found in only three of 15 fields being monitored statewide, he said. Even in those three fields, Wenninger said, the number of psyllids discovered were low — anywhere from one to four.
Growers who find psyllids may bring them to the Kimberly center — 3793 N. 3600 E. near the city of Kimberly — for examination.
Wenninger said 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.
South-central Idaho’s recent hot weather may be an ally for farmers in staving off zebra chip. Wenninger said it isn’t certain that high temperatures will stop the disease, but there’s some evidence that could be the case.
“Both the psyllids and the bacterium tend to not do well with high temperatures,” he said.
Wenninger added that close inspection of fields is the best strategy growers can take at this point.