Economic and social impacts of fusarium head blight: changing farms and rural communities in the northern great plains.

Fusarium head blight, also known as scab, can be a devastating disease on all classes of wheat and barley. Among the species of Fusarium that cause scab, F. graminearum is the predominant pathogen. Wheat and barley are highly susceptible to infection when the crop is in the flowering to soft dough stages and when weather includes frequent precipitation, high humidity, or heavy dews. Multiple symptoms occur: reduced yields, discolored and shriveled kernels (tombstones), depressed seed weights, and reduced seed quality and vigor. The mycotoxin deoxynivalenol (DON, commonly known as vomitoxin) also can be produced by F. graminearum on infected grain. Grain contaminated with DON often is unsuitable for flour, cereals, or malt and is too toxic as feed for nonruminant animals (19). Distribution of Fusarium head blight. In recent years, Fusarium head blight has reemerged worldwide as a disease of economic importance (19). In the United States and Canada, the reemergence of Fusarium head blight in the 1990s has caused epidemics of varying severity on barley and on all classes of wheat. It is documented as causing epidemics in 26 states (19) and the Canadian provinces of Quebec (A. Comeau, Agriculture and Agri-Food Canada, Ste. Foy, Quebec, Canada, personal communication), Ontario (A. W. Schaafsma, University of Guelph, Ridgetown College, Guelph, Ontario, personal communication), and Manitoba and Saskatchewan (R. Clear, Canadian Grain Commission, Winnipeg, Manitoba, personal communication). The United States Department of Agriculture (USDA) ranks Fusarium head blight as the worst plant disease to hit the nation since the stem rust epidemics of the 1950s (35). Wheat and barley losses caused by scab epidemics in the United States during the 1990s are estimated at close to $3 billion. American wheat farmers lost over 500 million bushels of wheat valued at about $2.5 billion (T. Sayler, Prairie Ag Communications, Fargo, ND, personal communication) and Midwestern barley producers lost $400 million on barley (J. Mittleider, North Dakota Barley Council, Fargo, personal communication). Economic losses to wheat producers in Canada in the 1990s are estimated in U.S. dollars at $220 million in Quebec and Ontario (A. Comeau, Agriculture and Agri-Food Canada, Ste. Foy, Quebec, personal communication) and, from 1993 to 1998, at $300 million in Manitoba (A. Tekauz, Agriculture and Agri-Food Canada, Winnipeg, Manitoba, personal communication). Why Fusarium head blight has been so severe. The disease has been favored by a combination of factors including unseasonably wet weather, particularly when plants are most susceptible. The increased practice of conservation tillage has favored inoculum of the pathogen to survive in residues of host crops such as wheat, barley, and corn. A high percentage of land has been planted to small grains, with short intervals between crops. Also, plant resistance to scab has been limited or absent in wheat and barley cultivars. These factors have resulted in the buildup and abundance of inoculum of F. graminearum. “Breadbasket of the World” under siege. The Northern Great Plains has a short growing season, so much of the land is tied to cereal production that includes hard red spring wheat, durum wheat, winter wheat, and barley. Beginning in 1993, northwestern Minnesota, eastern North Dakota, northeastern South Dakota, and southern Manitoba in Canada were particularly hard hit by Fusarium head blight and disease severities reached 20 to 80% (19). Epidemics of Fusarium head blight, however, have continued to reoccur every year from 1993 to 1998 at varying intensities, particularly in northeastern North Dakota, northwestern Minnesota, and southern Manitoba. In the last couple of summers, F. graminearum has spread further westward across North Dakota (M. McMullen, North Dakota State University, Fargo, personal communication) and from western Manitoba into Saskatchewan (R. Clear, Canadian Grain Commission, Winnipeg, Manitoba, personal communication). In the 1999 season, Fusarium head blight was a minor disease problem in Minnesota and North Dakota (although infections occurred as far west as the central portion of the state) and less of a problem in Manitoba compared with previous years. The Red River Valley, which I refer to occasionally in this presentation, is a 40to 60-mile region on each side the Red River that separates North Dakota and Minnesota and flows north into Manitoba. The flatlands of the Red River Valley are the lake bed of the prehistoric Lake Agassiz. It’s black loamy soil is among the richest farmland in the world. This region is the “Breadbasket of the World” and farmers here typically are prosperous. I live and work in northeastern North Dakota and northwestern Minnesota and have witnessed the impact of Fusarium head blight on the region. It has severely crippled the wheat and barley industries, driven producers to financial ruin and human hardship, and resulted in rural communities dwindling away. The epidemic has generated nearly $10 million in new public and private funding to support Fusarium head blight research and education in the United States (T. Sayler, Prairie Ag Communications, Fargo, ND, personal communication) and also has resulted in lobbying to change agricultural policies. In this address, I will focus on the development and impact of this crisis, with an emphasis on northeastern North Dakota and northwestern Minnesota. The summer of 1993 held great promise. Fields of wheat and barley were lush and green, and yield potentials promised to meet or exceed the bumper crops harvested in 1992. At harvest, growers were stunned and distressed when they found severe scab infecContribution No. 9910102 of the Minnesota Agricultural Experiment Station.