News section
home news forum careers events suppliers solutions markets resources directories advertise contacts search site plan
 
.
Zebra chip affecting tubers used to make potato chips

.

Welasco, Texas
February 19, 2007

Federal and state agricultural research scientists in South Texas have teamed up to combat a disorder in potatoes that affects the production of potato chips. So far, its cause is unknown.

The disorder, called Zebra chip for the dark stripes it leaves in the flesh of raw potatoes, is not harmful to human health, but causes serious and expensive reductions in crop yields and quality, the scientists said.

Crops have been affected in Guatemala, Mexico, Texas and as far north as Colorado. Symptoms are especially pronounced when potatoes are sliced and fried to make potato chips, causing frying plants to reject entire loads of affected potatoes. It also affects fresh market potatoes.

"Zebra chip defies typical diagnostic techniques that would point to a known bacteria or a virus causing this disorder, so we suspect it's something more complex," said Dr. John Goolsby, a research entomologist at the U.S. Department of Agriculture Kika de la Garza Subtropical Research Center at Weslaco.

Goolsby, who began studying the disorder in 2005, suspects whatever is causing Zebra chip is transmitted by insects.

"It appears to be vectored by an insect because when we place a cage over potato plants to exclude insects, the plants don't get Zebra chip,"

he said. "And of the insects we've evaluated, we believe it is vectored by the potato psyllid, an insect native to this part of the world. But we're not sure what the pathogen is."

Potato psyllids migrate north and south through the Great Plains of North America, overwinter in native vegetation in South Texas, but have never been a problem in the Rio Grande Valley, Goolsby said.

"What caused the change? We don't know," he said. "This happens often in insects. A different genotype emerges or a different pathogen becomes associated with the insect, but we suspect this is all caused by a native insect, not an exotic that has come in."

While USDA scientists continue basic research on the disorder and the vector insect, Texas A&M University System researchers are evaluating economic impacts of the disorder and ways to help growers deal with the issue.

An economic impact study by Texas A&M's department of agricultural economics showed that, left unabated, losses from Zebra chip would reach $100 million in lost business in Texas and almost 1,000 jobs.

"These economic impacts represent what could occur in Texas if Zebra chip is not controlled and eventually eliminated," the study said. "It appears likely that the condition could become more prevalent in the southern parts of Texas and in some regions may result in a complete loss of potato acreage. If this occurs, the economic impacts would be more severe, leading to greater losses in business activity, income and employment."

Jack Wallace Jr. grows about one-third of the Rio Grande Valley's 3,000 acre potato crop, located mostly in the McCook area. He and his family have been growing potatoes since 1964 and had no major problems until Zebra chip showed up in 2000.

"It's first noticeable as the plants are growing," he said. "You get foliar symptoms, usually after flowering. You see leaf curl, the upper leaves die off and a there's a yellowing effect."

Severity of Zebra chip varies from year to year and within a field, Wallace said.

"Last year was tough," he said. "This year the crop looks nice and pressures seem to be low, which could be attributable to the cool, wet winter we've had. But it's important to find out what's causing this Zebra chip because the livelihood of a lot of families depends on potato production. We've expressed this problem to our state senator, Juan ‘Chuy'

Hinojosa, who was very receptive, concerned and supportive of our plight."

To help growers in the short-term, Dr. T-X Liu, a Texas Agricultural Experiment Station entomologist in Weslaco, is evaluating 20 insecticides for their ability to control potato psyllid.

The tiny insects feed on juices of leaves using their piercing-sucking mouthparts and may be injecting some pathogens or toxins in the process, Liu said.

"We'll be evaluating 20 insecticides that were developed by five different companies for use on other pests," Liu said. "Hopefully, one or more will be effective against potato psyllid. We should start seeing results in April or May and have data a few months later."

Like growers, his research field plots of potatoes were planted at the Texas A&M Agricultural Research and Extension Center in Weslaco in December and will be harvested in the spring, Liu said. He is currently rearing populations of potato psyllids to be released into those field plots.

Dr. Boris Castro, a Texas Cooperative Extension entomologist, will be involved in developing long-term, integrated pest management solutions to control Zebra chip and potato psyllids, which can also affect tomato crops.

Goolsby said solutions developed here will be applied to other potato production regions.

"Zebra chip is not limited to Texas," he said. "But South Texas is where the problem first showed up in the U.S. in 2000, so this is where we've assembled the research team to combat this problem. We're investigating every possible aspect, and once we figure out how to manage Zebra chip, those solutions will be shared with potato production zones farther north."

Writer: Rod Santa Ana III

 

 

 

 

The news item on this page is copyright by the organization where it originated - Fair use notice

Other news from this source


Copyright © SeedQuest - All rights reserved