Zebra chip discovery in Pacific Northwest spuds raises questions

11/18/2011 05:58:00 PM
Vicky Boyd

Most of the samples have come from fields in the Magic Valley region of Idaho near Twin Falls, but a few have come from the Treasure Valley nearer Boise.

The disease has been found in several varieties, including Russet Burbank, Ranger Russet, Ranger Norkotah, Yukon Gold and one for chipping, Olsen says.

In the coming weeks, she says she and her colleagues hope to get a better handle on the number of infected fields and the disease’s distribution in the state.

Idaho grower group concerned

The discovery of zebra chip in Idaho has that state’s growers concerned both from a pest management and a public relations standpoint, says Todd Cornelison, industry relations manager for the Eagle-based Idaho Potato Commission.

“The first thing that everybody needs to know is [zebra chip] isn’t a health issue for humans. It’s strictly a potato quality issue,” he says.

The good news, at least from what Cornelison has learned from researchers, is the psyllids don’t overwinter in Idaho because of the cold temperatures. Instead, they migrate into the fields late in the season.

Even if zebra chip eventually becomes an issue, he says it would probably be limited to a late-season problem.

Growers and consultants already walk fields to monitor aphid populations, which can spread PVY, or potato virus Y.

Now they’ll have to add psyllids to the list of pests for which they scout.

“We set out traps and if aphid numbers get too high, we treat with insecticide,” Cornelison says. “That’s exactly what we’re going to do with zebra chip—trap psyllids to see how much pressure there is. We’ve learned this from Texas, and Texas has shown us quite a bit.”

Zebra chip discovery wasn’t unexpected

The discovery of zebra chip in the Pacific Northwest wasn’t totally unexpected, says Joe Munyaneza, a research entomologist with the Agricultural Research Service in Wapato, Wash.

From 2005 through 2008, Munyaneza began catching potato psyllids about mid-July in potato fields near Moxee and Prosser, Wash. Caged field experiments conducted in Texas with psyllids collected in Washington showed the insects could produce zebra chip.

If the insects were to arrive in Washington fields early enough in the season, he says they could cause potentially serious damage.



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