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Study: Alfalfa disease hits Northeast
2007-11-09
A fungus that attacks alfalfa, leaving rotting brown lesions, has been detected in farm fields in New York and four other Northeastern states, scientists said. The so-called "brown root rot" was detected in eight of 10 fields sampled in New York, six of seven fields in Vermont and five of six fields in New Hampshire, Cornell University researchers reported in the October 2007 issue of the journal Plant Disease. The samplings were conducted in 2005. Since then, the disease has also been found in Pennsylvania and Maine, the scientists said. "It appears widespread. These were arbitrarily chosen fields spread out across each state," said Gary Bergstrom, a professor of plant pathology at Cornell. "Not only was it found in a high percentage of plants in many fields, most lesions had advanced to the internal tissues of roots and crowns," Bergstrom said in a phone interview. There are no effective treatments or controls for brown root rot, he said. Feed stock is an important crop for dairy farmers. There are approximately 700,000 acres of alfalfa and alfalfa mixes grown across New York state, according to the Northern New York Agricultural Development Program. "The numbers are alarming," said Peter Gregg, a spokesman for the New York Farm Bureau, a 30,000-member statewide advocacy group for farmers and agriculture. "The past couple of years it has grabbed our attention and suddenly it's become a big problem. To the extent Cornell is reporting it, we did not realize it was that bad," Gregg said. Last year, the Farm Bureau persuaded state lawmakers to spend $300,000 for research on the fungus, which can also infect vegetables and Christmas trees, he said. "It's a fungal disease that has a lot of mystery to it. We are encouraging more research to find ways to eradicate it from New York fields," Gregg said. Neither the Farm Bureau nor the state Agriculture and Markets Department have kept track of the number of infected acres in New York. "We aren't hearing about any significant crop losses, but we are finding that the disease is quite prevalent," said Jessica Chittenden, an agriculture department spokeswoman. Brown root rot started out as a problem in Alaska and in the prairie provinces of western Canada -- Alberta, Saskatchewan, Manitoba and the Yukon Territory. In eastern Canada, it has been reported only in Nova Scotia. The disease was first observed in the contiguous United States in 1996 in Wyoming and then in Idaho, Montana, Minnesota and Wisconsin. The fungus first appeared in New York in 2004 in Clinton County, Bergstrom said. The disease's lesions first appear as reddish-brown to dark brown areas of external discoloration, eventually progressing into the roots, said Michael Wunsch, a Cornell graduate student in plant pathology and the report's lead author. The fungus prefers cooler soils, between 30 and 60 degrees. Infection and decay occur primarily in the late fall through early spring. Infected plants grow normally in the spring but die in mid-May to mid-June. Bergstrom said the widespread detection of brown root rot in the testing indicates most fields already have the pathogen. He said the best thing farmers can do at this point is to buy stronger, disease-resistant alfalfa in the future. "Once it's in the soil, it's not realistic to think about eradicating it," Bergstrom said.
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