New test can curb losses of potatoes in storage

Zahi K. Atallah has seen it happen so many times before. "Year in and year out, we look at the fields and they look beautiful. We harvest the spuds, and they look outstanding," says Atallah, a University of Wisconsin–Madison postdoctoral researcher in the plant pathology department. "Then we store them, and they turn into mush."

For potato growers, a good harvest doesn’t automatically mean a good year. Every year, about 8 to 9 percent of the nation’s potato crop goes bad sitting in storage lockers while waiting to go to a chip or fry factory. That’s a loss of about $16 million worth of potatoes in Wisconsin alone.

In an effort to curb this type of loss, Atallah developed a test that will enable farmers to better separate potatoes fit for long-term storage from those that are not. The test, which will be offered through a Wisconsin company specializing in plant disease diagnostics, involves collecting healthy-looking tubers from the field before harvest, cleaning and juicing them, and then extracting their genetic material.

Using a technique known as polymerase chain reaction, or PCR, a technician can look at the DNA contained in each sample and detect foreign microbial agents that cause storage losses, including late blight, pink rot and fusarium. The results will tell farmers, on a field-by-field basis, which potatoes have high levels of these microbes.

"So, instead of storing the good with the bad, now growers can do triage," says Atallah. The potatoes that have a high risk of spoiling in storage can be sent for processing immediately or stored for a short amount of time. The ones that look good, on the other hand, can be put into long-term storage, he explains.

Early on, Atallah’s project — which was funded by the Wisconsin Potato and Vegetable Growers Association and the U.S. Department of Agriculture — attracted the interest of Randy Van Haren, co-founder of Pest Pros, Inc., a crop consulting firm and plant disease diagnostic laboratory located in Plainfield, Wis. "I’ve always been interested in the power of PCR technology, and have kept my eye on it. After hearing [about Atallah’s project], I thought to myself, ‘It’s time to start investing in this technology,’" says Van Haren.

The company worked with Atallah and Walter Stevenson, a UW–Madison plant pathologist who specializes in potatoes, to help speed commercialization of the test. Now with the capacity to run the test in-house, Pest Pros will begin promoting the potato pathogen assay next year.

This assay is the first of many PCR-based diagnostic tests that Van Haren plans to offer. "PCR is very fast and very sensitive," he says. "The future of growth in our business is going to be in PCR technology."