June 23, 2010
Contacts: See list at end of release

Northern NY is Eastern U.S. Center for Brown Root Rot Research

Northern New York has become a significant center for research on brown root rot, the soil-borne fungus causing root and crown rot of alfalfa, other perennial legumes, and overwintering grasses. The fungus Phoma sclerotioides, associated with yield loss, winterkill, slow crop emergence after winter dormancy, and stand decline, was first detected in the eastern U.S. in a Clinton County (Northern NY) alfalfa field in 2003.

With small grants funding from the farmer-driven Northern New York Agricultural Development Program, Cornell University established research trials and a BRR-resistant alfalfa nursery program at the W.H. Miner Agricultural Research Institute at Chazy, NY.

“Because the Cornell-managed BRR test plots at the Miner Institute contain natural populations of all five subtypes of the BRR fungus that occur in eastern North America, the Northern New York site is an ideal location for evaluating alfalfa germplasm for BRR resistance,” says BRR project leader Gary C. Bergstrom, a Cornell Plant Pathologist.

“I believe the research plots at Chazy are the only ones in the eastern U.S. that have been inoculated with the BRR fungus,” he adds. “The research being conducted in Northern New York is critical to helping farmers manage brown root rot by identifying resistant varieties.”

Preliminary research suggests that alfalfa cultivars resistant to one subtype of the fungus may be susceptible to other subtypes.

At least seven genetically distinct subtypes of the BRR fungus occur in North America and five of the subtypes are found in eastern North America. Identifying varieties that will show BRR resistance across New York and the Northeast requires screening against all major subtypes of the fungus.

“Identification of varieties with resistance to multiple subtypes is important,” Bergstrom adds.

The Northern New York Agricultural Development Program, which receives funding from the New York State Senate, underwrote a 6-county survey to determine if BRR is affecting forage crops in Clinton, Essex, Franklin, Jefferson, Lewis, and St. Lawrence counties.

“The good news is that while we found BRR present in the forage grasses in Northern New York, it does not appear to be causing much, if any, damage to bromegrass, tall fescue, orchardgrass, reed canarygrass, perennial rye or timothy, or in winter wheat crops evaluated in southern New York State,” Bergstrom says.

“The bad news is that alfalfa appears to a primary host for the fungus, and it survives in a number of weeds making it a broad-host organism that will not allow control by crop rotation practices,” Bergstrom adds. “The long-term solution to BRR is in identifying, breeding and planting resistant varieties.”

As a Cornell graduate student Michael Wunsch, now a plant pathologist at North Dakota State University, conducted foundational research to characterize BRR in the Northeast and he began the work to identify the more BRR-resistant varieties of alfalfa growing under Northern New York conditions. He also collected BRR research data from Western Canada where farmers have seen success with BRR-resistance varieties.

“A multi-year, two-location field study conducted in Saskatchewan fields with high brown root rot pressure showed that in the second and third production years, alfalfa varieties with elevated BRR resistance yielded 40 to 65 percent higher than varieties highly susceptible to BRR. Alfalfa varieties with moderate BRR resistance yielded 23 to 43 percent higher than alfalfa varieties highly susceptible to the fungus,” Wunsch says.

“Peace” and other BRR-resistant alfalfa cultivars grown in Saskatchewan and Alberta, however, perform poorly in New York.

“Northern New York provides a perfect screening laboratory for testing varieties in the harshest environment where brown root rot exists, and the nursery program at Chazy dedicated to identifying the alfalfa varieties that will best tolerate BRR is creating a foundation for selective breeding of BRR-resistance alfalfa,” Bergstrom adds.

Cornell Plant Breeding & Genetics researchers Julie L. Hansen and Donald R. Viands are spearheading the continuing BRR nursery at Chazy and will conduct yield evaluations. An analysis of plants that have been through one winter of BRR-resistance testing is currently underway at the Cornell plant pathology lab at Ithaca, NY.

BRR research, photos and analyses are posted on the Northern New York Agricultural Development Program website at www.nnyagdev.org in the Alfalfa section.

In the Northeast, BRR is currently found in New York, Vermont, New Hampshire, Pennsylvania and Maine, as well as in areas of eastern Canada.

Click to enlarge photo

CONTACTS
Northern New York Agricultural Development Program Co-Chairs: Eastern NNY: Joe Giroux, 518-565-4730 (work); Western NNY: Jon Greenwood, 315-386-3231 (farm)

Cornell Researchers
• Gary C. Bergstrom, Plant Pathology, 607-255-7840, gcb3@cornell.edu
• Donald R. Viands, Plant Breeding & Genetics: analyzing alfalfa samples for BRR resistance and possible selective breeding, 607-255-3081, drv3@cornell.edu
• Julie L. Hansen, Plant Breeding & Genetics: managing research plots at Chazy, NY, 607-255-5043, jlh17@cornell.edu

Associates: Michael Wunsch, North Dakota State University Plant Pathology, 701-652-2951