Idaho works to stay ahead of zebra chip disease

10/30/2012 12:24:00 PM
Vicky Boyd

Zebra chip disease doesn’t pose a serious threat to the Idaho potato crop, but the industry is focusing efforts on it since it has been found in scattered Idaho potato fields this season.

It’s just another pest, such as late blight or Colorado potato beetle, growers will have to learn to manage, said Erik Wenninger, assistant professor of entomology at University of Idaho Kimberly Research and Extension Center.

“Growers have been hit with one problem after another over the years, and this is just another issue that we’ll have to learn to live with,” he said.

Wenninger said he didn’t believe zebra chip in Idaho would be as serious a threat as it is in Texas, where potato psyllids — the insects that spread the disease — are present most of the growing season. As a result, the plants can be infected at a much younger age, increasing damage.

Still, Wenninger said he and fellow researchers have a lot to learn about the pest’s behavior in Idaho.

zebra chip in baked potatoes Joseph Munyaneza, Agricultural Research ServiceZebra chip disease affects the way potatoes store sugars and starches, creating discoloration when the tubers are baked.Until last year, for example, they believed potato psyllids didn’t overwinter in the Pacific Northwest, instead migrating into the region during late summer.

Whether because of last year’s mild weather or another factor, potato psyllids overwintered from 2011 to 2012, he said.

Zebra chip 101

Potato psyllids — insects about the size of green peach aphids — spread zebra chip when they feed on an infected potato plant, pick up the bacterium and then feed on a healthy one.

The zebra chip organism, known scientifically as Liberibacter solanacearum, changes the way the potato plant stores starches and sugars in tubers. It is harmless to humans or other animals.

When potatoes are cooked at high temperatures, such as during frying, the sugars caramelize, causing brown stripes.

The disease also affects plant growth and reduces overall tuber yield.

When the disease was first confirmed in Texas in 2000, many considered it a chipping problem or a Texas problem.

Since then, both the disease and the potato psyllid have spread to most potato-producing states and have been found in fresh-market, processing, chipping and seed potatoes.

Research conducted by Texas A&M University also has shown that no potato variety is resistant to the disease, although some varieties are mores susceptible than others.

The University of Idaho received a $109,000 grant this fall from the U.S. Department of Agriculture to help monitor potato fields for psyllids.

The grant also will help fund research led by Nora Olsen, director of the Potato Storage Research Facility, Kimberly, about how zebra chip affects tubers in storage.

Knowing University of Idaho researchers as he does, Gary Garnand, owner of Garnand Marketing LLC, Twin Falls, Idaho, said he’s confident of their ability to find solutions.

“They’re on it like a wet blanket,” Garnand said. “They will find a way of helping slow this down or stopping it.”

Despite the isolated psyllid and disease incidence, the Idaho potato industry is taking the threat seriously, said Frank Muir, president and chief executive officer of the Eagle-based Idaho Potato Commission.

“Zebra chip is a big challenge, and we’re working with the University of Idaho to try to determine the best way to control it,” he said. “We’ve tried to be ahead of this because we saw it come into Texas and the Southwestern states. We knew there was a chance that the critters would find their way up here, and they did.”

Trade issues

As a result of zebra chip, the South Korean government has banned the import of tablestock potatoes from the Pacific Northwest. Fresh potatoes shipped for processing have beek approved again.

The tablestock ban has a minimal effect on Idaho, since the state had just begun shipping fresh potatoes to South Korea after being out of that market for some time, Muir said.

Nevertheless, he said Idaho is working with Washington and Oregon to help the South Korean government understand the steps the states are taking to prevent the spread of zebra chip.

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Peter McClure    
Florida  |  November, 10, 2012 at 12:58 PM

In this article, potato growers echo the same "normalcy bias" (google that term) citrus growers have repeatedly made everywhere with citrus greening, also caused by a psyllid/liberibacter disease complex. Potatoes have the huge advantage of not being a perennial, but this pest/disease complex is always far worse than growers can imagine. The fact that the potato psyllid is overwintering when it was expected not to is an example of that. Potato growers need to fully fund and self-manage the research to get ahead of this and solve the disease problem, not play catch up after its too late. USDA and University research institutions are not designed to provide timely solutions without stakeholder oversight. California citrus growers, with full blown normalcy bias in play, are going to suffer the fate of Florida citrus growers by not seriously ramping up their R&D to solve this problem. Wake up spud farmers, this is bad stuff!

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