Wisconsin Potato and Vegetable Growers Association: 68,000 acres of Wisconsin potatoes and all is well despite late blight fungus

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Growers’ Preventative Steps Ensure Hearty Harvest and Plentiful Seed Potatoes for Next Year

Antigo, WI — September 8, 2009 — “Worst case scenario — if no preventative steps had been taken, then yes, we could have had 100% crop loss of 68,000 acres of potatoes,” notes Amanda Gevens, plant pathologist with University of Wisconsin-Madison and the University of Wisconsin Extension, in reference to the spread of the late blight fungus from the eastern seaboard to the Midwest. “But Wisconsin potato growers have been very vigilant — taking preventative measures such as applying fungicides and having professional scouts inspect their fields. Because of the late blight outbreaks in the late 1990s and early 2000s, we had the experience and knowledge to contain late blight and limit the risk to the current crop and next year’s seed potatoes.”

Adds AJ Bussan, Associate Professor in the Department of Horticulture at the University of Wisconsin- Madison, “At this point, the volume of stored potatoes does not appear to be in jeopardy. All the growers have been taking preventative action for the last six to eight weeks, and we’ve only had a single case in which late blight was found in a production field.” The field, located in Portage County, had one small sector of blight located in a far corner of the field. The plants were immediately destroyed, as were those in a buffer zone surrounding the infested plants. Fungicides were used to stop subsequent lesions on plants that were found by scouts. The lesions were not active — thus preventing the spores from spreading by air. No potatoes were harvested from the infected plants.

Late blight, responsible for the great famine in Ireland in the 1840s and 1850s, has the potential to destroy crops around the nation because the spores can travel long distances via air. “But this isn’t the nineteenth-century,” notes Gevens. “We have the know-how and the tools to contain infestations. Preventative measures, including those of commercial growers and home gardeners, have been key. We were able to get the word out across the state and home gardeners did an excellent job of reporting suspected cases of blight on tomatoes and potatoes, and destroying suspicious plants. Believe it or not, that’s key to containing the infestation as well — monitoring one’s personal garden. In fact, the current late blight infestation has been traced back to tomato plants purchased by unwitting consumers in New York. The spores spread to farmers from eastern South Carolina to Maine then headed westward through New Jersey, Pennsylvania, Ohio and Michigan. We all have the same strain of blight.”

There are several factors that have helped contain the spread of late blight in Wisconsin. “This summer has been unseasonably cool and wet — very favorable conditions for blight — so we were on the alert,” notes Gevens. “Once we were made aware of the breakout of late blight on the East coast, we sent notices to Wisconsin growers. Growers also follow our disease forecasting which is based on weather data, temperature, rainfall and humidity. The unusual summer weather was an indicator of risk, so growers began spraying fungicides for late blight many weeks in advance of the finds in Dane County.”

Another factor that helped prevent a widespread outbreak is timing. “We’ve gotten the tail end of this — it started in June on the east coast. Now, in September, growers are already performing vine kill, which helps the potato skin ‘set up’ — or thicken. This makes the potato more resistant to disease.” By killing the green foliage, growers not only prepare their crop for harvest, but eliminate the green plant material that late blight needs to survive.”

Continues Gevens, “Infected plant materials can be left atop the soil where the brutal Wisconsin winters destroy any further traces of the blight. In spring, the plants or potatoes are tilled into the top soil to ensure they fully biodegrade.”

As for seed production, a strict certification regimen is in place to ensure infected tubers are removed from seed lots.

“Did we get lucky?” asks Gevens. “Yes and no. Certainly having the spores reach our area at the tail-end of summer has been key. But the growers and gardeners throughout the state were very proactive and vigilant — and that, ultimately, has been the key to ensuring a healthy harvest.”

Ranked third in the nation for potato production, Wisconsin harvested 2.3 billion pounds of potatoes in 2008, generating over $300 million in product dollars for farmers and shippers. Agribusiness in Wisconsin generated $51.5 billion in economic activity and provided jobs for 420,000 people — about one out of every eight residents works in a job related to farming.

About Wisconsin Potato and Vegetable Growers Association (WPVGA)

Established in 1948, the WPVGA is headquartered in Antigo, Wisconsin. WPVGA provides grower education, government support, environmentally sound research and consumer education for 150 grower organizations across the state. WPVGA is responsible for expanding the Wisconsin potato markets through advertising, promotion and research. WPVGA also supports the Wisconsin Healthy Grown® initiative — reduced crop protection inputs, integrated pest management, sustainable farming practices overseen by Protected Harvest, an independent oversight organization. http://www.wisconsinpotatoes.com.