Capital Press

Two adult potato psyllids were found on yellow sticky cards that were collected June 19 from a Twin Falls County potato field, according to an alert issued Tuesday by University of Idaho Extension staff.

The psyllids can spread zebra chip, a crop disease that hurts potato yields and leaves bands in tuber flesh that darken when fried. The disease first arrived in the Pacific Northwest last season, and growers have utilized an intensive monitoring program to locate the psyllids this year.

The insects -- which were the first psyllids found in an Idaho field this year -- are now being tested to determine if they harbor the Liberibacter bacteria that causes zebra chip. Andy Jensen, a research entomologist who works for the Idaho, Washington and Oregon potato commissions, said Alex Karasev with the U of I in Moscow is conducting the tests, and he hopes results will be available later this week.

Jensen said a U of I team funded by the Idaho Potato Commission and led by Erik Wenninger, with the U of I Research and Extension Center in Kimberly, made the discovery from surveys of growers' fields.

Psyllids were found more than two weeks ago in Columbia Basin potatoes. In addition to Oregon fields, adult psyllids, eggs and nymphs been found in Washington research plots, Jensen said.

"It means psyllids have been there long enough and successfully enough to start reproducing," Jensen said.

Preliminary testing of some of the psyllids discovered so far concludes they're a resident population that overwintered, Jensen said.

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