Fusarium head blight, a plant disease also known as wheat scab, has taken aim at America's breadbasket and threatens New York's $30 million wheat-growing industry, according to Cornell plant pathologists. The scientists will be speaking at the American Phytopathological Society's annual meeting, Aug. 9-13, in Rochester, N.Y.

"Wheat is an important crop in New York state. As in most of the Midwestern states, epidemics of scab disease threaten New York's wheat industry," said Gary Bergstrom, Cornell professor of plant pathology.

In New York, winter wheat is grown on 120,000 to 150,000 acres annually, primarily in the western and central parts of the state, he said. The wheat grain, with a New York grower cash receipt value of approximately $30 million annually, also is milled and processed by several New York food companies into flour for crackers and other pastry products for human consumption.

But, the scab is increasing as a threat to sustainable wheat production. In 1996, New York wheat farmers lost more than $12 million due to the widespread occurrence of scab, Bergstrom said. "All of our adapted pastry wheat varieties are susceptible to scab, which is most severe when wet weather occurs while the crop flowers in late May-early June," he said.

Fortunately, wet weather was not encountered during wheat flowering this year in New York, and preliminary estimates call for excellent yields of New York winter wheat in 1997.

In the Midwest -- North Dakota, South Dakota and Minnesota -- yield and grain quality losses amounted to nearly $1 billion in 1993 and ranged from $200 million to $400 million annually since then. In Ohio, Michigan, Indiana and Illinois, losses from wheat scab exceeded $300 million in 1995 and 1996. Food safety is also an issue with the scab, as products made from the infected grain could be contaminated by a mold by-product, a poison known as vomitoxin.

Cornell researchers are collaborating with colleagues at the Brazilian Wheat Research Center (EMBRAPA Trigo) in Passo Fundo, Brazil, to examine the potential for using naturally occurring microorganisms to fight fungal infections of wheat and corn plants in both the United States and Brazil.

Wilmar da Luz, Cornell Ph.D. '86, directs the project in Brazil and is working with Bergstrom. Brazilian scientists have isolated thousands of strains of bacteria and yeast growing naturally on plant leaves, roots and soil that exhibit anti-fungal activity. The researchers also are examining some promising microbial strains and assessing them in greenhouse experiments for their ability to control a range of diseases caused by fungi in corn and wheat.

Bergstrom and da Luz report promising results in greenhouse studies with bioprotectant bacteria sprayed on wheat heads before they sprayed the wheat heads with Fusarium spores. Bio-protected plants showed fewer diseased grains with significantly lower levels of contamination by vomitoxin than did non-protected plants.

Bergstrom, da Luz and Christine Stockwell, Cornell postdoctoral plant pathologist, will make two presentations at the APS convention. The first, a paper, "Biocontrol of wheat scab with microbial antagonists" will be presented Aug. 10 at 10:15 a.m. The second, "Seed microbiolization for control of Fusarium species in cereals," will be presented as a poster Aug. 12-13.

Application of the bioprotectant strains to cereal crop seeds promoted the germination of seeds in soil to the same extent as did treatment with chemical fungicides. Initial tests in Brazil indicate that the biocontrol strains are also effective in controlling disease under field conditions. The research team will test biocontrol strains in field plots in New York in 1998.

"Biological control may become an important component in controlling wheat scab and other cereal diseases, while at the same time increasing the quality of wheat grain for human consumption," Bergstrom said.

"There is no quick solution to the wheat scab problem. It requires extensive basic and adaptive research and testing of new approaches under localized wheat production conditions," Bergstrom added. "Researcher efforts are already under way for investigating new avenues for the management of wheat scab, and we are cooperating with researchers in other states. Unfortunately, these efforts are proceeding very slowly due to limited funding available for this research."