Fusarium graminearum is the causal agent of head blight (scab) of wheat and barley, a plant disease with great impact on U.S. agriculture and society during the past decade. Approximately $3 billion were lost in the U.S. during wheat scab epidemics in the 1990s, resulting in devastating effects on farm communities in the upper Midwest and elsewhere. Moreover, the disease is becoming a threat to the world's food supply due to recent head blight outbreaks in Asia, Canada, Europe and South America. The fungus also infects and causes disease on corn and rice. The pathogen poses a two-fold threat: first, infested cereals are significantly reduced in seed quality and yield, and secondly, scabby grain is contaminated with trichothecene and estrogenic mycotoxins, making it unsuitable for food or feed. As a food safety issue, trichothecene toxins such as "vomitoxin" (deoxynivalenol) pose a serious hazard to human and animal health because these sesquiterpenoids are potent inhibitors of eukaryotic protein biosynthesis. Vomitoxin causes weight loss and feeding refusal in non-ruminant livestock, and human ingestion of grain contaminated with F. graminearum has been associated with alimentary toxic aleukia as well as illness characterized by nausea, vomiting, anorexia, and convulsions. Trichothecenes also are powerful modulators of human immune function and may promote neoplasms, cause autoimmune disease, or have long-term effects on resistance to infectious disease by altering immune response.