Zebra chip found in two southern Idaho counties

The University of Idaho reports that zebra chip has been confirmed in Idaho by USDA Agricultural Research Service tests of samples from a potato processor. The affected potatoes were tracked to a field in Jerome County. Several confirmed reports also recently were made in Twin Falls County. Although the pest was found in several fields, the number of plants infected initially appeared low.

Intensive sampling at the Kimberly Research and Extension Center showed the insects had infected several varieties, said University of Idaho Extension potato specialist and storage researcher Nora Olsen.

“The question is whether this is an artifact of the unusual weather we had earlier this year or whether this is going to be a long-term problem,” Olsen said.

Zebra chip is named for the dark bands that develop in potatoes infected by the bacteria that are carried by psyllids. The tiny cicada-like insects related to aphids are normally found in warmer regions than the Inland Northwest’s prime potato country.

A threat to potato quality for growers and processors, zebra chip can reduce the value of both fresh and process potatoes. It particularly affects processed products such as French fries and potato chips by creating darker chips and fries.

The dark coloration results from changes in stored sugars that caramelize when the potatoes are processed. Potato products showing signs of zebra chip are removed before packaging due to their appearance.

Zebra chip had been reported last month in the southern Columbia Basin region bordering Oregon and Washington.