Massive Efforts Halt an Airborne Enemy

When you buy a spud at the grocery store, you might not think about where it came from. Chances are, however, you're purchasing a product of Colorado. Colorado ranks second in the nation for fresh market potato production.

Most of those potatoes come from the ground of the San Luis Valley–they're big business there. Approximately 90 percent of the Colorado crop is grown in this south central part of the state, making potatoes the number-one agricultural industry–and providing the majority of jobs–in the Valley. Potato fields cover 77,000 acres and produce 30 million 100-pound bags each year with a market value of $117 million.

"Until recent years, potatoes have been relatively painless to grow in the San Luis Valley," said Richard Zink, Colorado State University Extension potato specialist.

Because of its arid, isolated conditions, the San Luis Valley had the distinction of being the only potato production area in the United States free of late blight. But during the 1998 growing season this distinction and the competitive advantage it afforded local growers was swept away in August when late blight was detected. Potato late blight is a disease that, without the proper response, can potentially destroy all the Valley's potato crop within a few days. That threat now looms each season.

Phil Smartt, owner of Blue Sky Farms near Monta Vista, had raised potatoes in the Valley since 1977, before the late blight was a concern. When symptoms of the blight showed up in the area two years ago, Smartt, and every potato farmer there, had to make drastic adjustments in their production methods. Extension helped develop an educational campaign in an effort to slow the spread of the disease from field to field and from vine to tubers.

Now, potato farmers, scientists and professional crop consultants scour fields daily during the summer and early fall, when the blight begins to show. When they aren't painstakingly searching for the tell-tale dead spots on a leaf, they're undertaking preventative methods to avoid a breakout. Once the blight starts, it can spread on a breeze for several miles, infecting every acre of potatoes in its path within a short time.

Because the blight spreads so quickly, daily reports are critical to every farmer's success. What was once a relatively low-maintenance crop to grow has become expensive and exhausting. Potato farmers have always sprayed their Crops with fungicides, but, before, the applications were minimal–about once or twice a season. Now, from July until September's harvest, farmers undertake an aggressive program of preventive fungicide applications, spraying as often as every week to protect their Crops from an outbreak of late blight. When it does appear--and it will make annual calls--the fungicide will make the disease spread less quickly and less densely, causing less damage.

Valley farmers like Smartt turned to Extension for help in keeping ahead of the devastating disease.

"There are other sources to turn to for information about the blight," said Smartt. "But Extension has a lot to give to the community, and they make information very available. They have the educational background, expertise and experience to help us fight the blight. I enjoy working with them...and I trust them."

Zink has a community-wide communication system in place to alert farmers about a blight outbreak and its severity. The blight can't be prevented or treated; it can only be controlled by timely fungicide applications. Quick and accurate communication about the general location and extent of an outbreak can mean the difference between a profit and a total loss for a farmer.

Zink is also working in the community to start a composting service to give farmers a safe place to dispose of blight-infected potatoes. Composting destroys the fungus that causes late blight.

"When you look across the whole industry in Colorado, you see that producers are spending about $15 million each year to prevent a late-blight disaster," said Zink. "Extension has put together a late-blight management plan for Colorado, which includes disease scenarios, management techniques, workshops and grower meetings."

Zink has been instrumental in putting together laws for potato disposal, imports and exports. He's among researchers in the Valley who continuously search for additional controls for late blight, trying combinations of fungicides and new products on trial Crops. He works with producers in the other areas of the state, near Greeley and the Kansas border, who also struggle with the blight.

Smartt said he attends workshops, classes and meetings that Zink and other professionals hold regularly to keep farmer's updated about the blight. "The teamwork between Extension, consultants, chemical companies and farmers is apparent--and critical," said Smartt. "I wish there were more resources available to Extension, because they'd be available to us when we need them. I appreciate their knowledge, experience and dedication to our business and our success."

Photo Cutline: Phil Smartt (center), potato producer, along with every potato farmer in the San Luis Valley, had to make drastic adjustments in their production methods when symptoms of late blight showed up in the area two years ago. A team effort between Extension Agent Richard Zink (left), area consultants, chemical companies and producers was critical to the effort to slow the spread of the disease.

For more information, contact your local Colorado State University Extension office.

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