A potato pest from points south has reached Idaho, University of Idaho Extension specialists confirmed in early October.
Zebra chip, named for dark bands that develop in potatoes infected by the bacteria carried by the phyllids, are normally found in warmer regions than in 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 processed product. It particularly affects processed products such as French fries and potato chips creating darker colors than is desired in these products.
The discoloration 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.
Presence of zebra chip in Idaho was confirmed by the USDA Agricultural Research Service from tests from a potato processor. The affected potatoes were tracked to a field in Jerome County. Several confirmed reports were also recently made in Twin Falls County.
Although the pest was found in several fields, the number of infected plants appeared to be low.
Intensive sampling at the Kimberly Research and Extension Center showed the insects had infected several varieties, reports UI Extension potato specialist and storage researcher Nora Olsen.
"The question is whether this is an artifact of unusual weather we had earlier this year, or whether it is going to be a long-term problem," says Olsen.
Because of its quality impact, zebra chip can be a serious problem for the industry. Potatoes are Idaho's top crop, generating $915 million in 2010, and reductions in that income could have profound results in the state's economy.
Zebra chip also provides a threat to fresh potato markets, although homeowners will probably not notice the stripping problem once the product is mashed or baked. There are no known health safety or nutritional problems associated with the pest.