By JOHN O'CONNELL
TWIN FALLS, Idaho -- Researchers say two adult potato psyllids, vectors of the crop disease zebra chip, were recently caught on sticky traps in the Magic Valley.
The aphid-like, winged insects were found in late March on traps near Shoshone Falls, according to a recent posting of the University of Idaho-run Idaho Pest Alert Network. The psyllids will soon be tested for the liberibacter bacterium that causes zebra chip.
Zebra chip, which creates bands in tuber flesh that darken when fried, first arrived in the Pacific Northwest in 2011. The traps were set by U of I zebra chip researchers.
Andy Jensen, regional research director for the Idaho, Washington and Oregon potato commissions, said no psyllids have been found in Magic Valley by direct inspection of bitter nightshade plants, which provide an alternative host for the insects, so it's still conceivable they may have migrated from elsewhere. However, he said the evidence suggests the psyllids most likely overwintered here.
Prior to the discovery in Twin Falls, Jensen found psyllids on bitter nightshade in the Boise area in early February and again in March. The initial detection in Boise surprised Jensen, as the region experienced one of its coldest winters on record. Now it seems likely that they also survived in a slightly colder environment farther east, he said.
Because bitter nightshade grows along waterways, Jensen said fields near rivers and water may be more at risk. Bitter nightshade sprouts from above-ground vines that lose their leaves in fall, Jensen said.
"The bitter nightshade is now out of dormancy and growing. It means as far as psyllids are concerned, the winter is over," Jensen said. "They've got green plant material to live on."