The primary purpose of the American Phytopathological Society (APS), with approximately 5000 members, is to promote the discovery and diffusion of scientific information on plant diseases and their control in the United States and world-wide. This purpose includes the dissemination of scientific information needed to make and implement sound national and international policies on plant diseases and their control. This statement has been developed and approved by the APS Council in August, 1996.
Virtually every smut or bunt disease once important on cereal grains (wheat, barley, rice, corn, sorghum, oats) is or can be effectively managed today by 1) seed-treatment chemicals, 2) resistant varieties, and/or 3) the use of cultural practices such as change in planting date or lengthening the crop rotation. Even where seed treatments have been ineffective against soilborne spores, it has still been possible to manage these diseases through the use of cultural practices and resistant varieties. These management options are in addition to the use of clean, high-quality seed. Thus, the scientific information available does not support a "zero tolerance" requirement for spores in seed lots as the standard for smut and bunt diseases of cereals, including for Karnal bunt of wheat. In the specific case of Karnal bunt, experience from countries where this disease has occurred would suggest further that this is a minor disease, and what little risk does exist can be effectively managed without the use of quarantines.
Although quarantines may delay introductions of pathogens into new areas, they are unlikely to absolutely prevent such introductions and subsequent establishment. This conclusion has been confirmed repeatedly, most recently by the occurrence of Karnal bunt in the United States despite quarantines imposed on wheat from countries where this disease has been known to occur. Considering the flow of agricultural goods and products of international commerce, and the ability of the Karnal bunt fungus to travel considerable distances as airborne spores, the opportunities for movement of these fungi are enormous. Moreover, in regions where bunts and smuts occur, there is no evidence or experience to suggest that a smut or bunt fungus can be eradicated once established in soil. In the specific case of Karnal bunt in the United States, new soil infestations can be expected in the future because the causal fungus is both widespread in Mexico in areas adjacent to wheat-growing areas in the United States and because it spreads as airborne spores.
The smut and bunt diseases of wheat and other cereals were among the first plant diseases recognized by the early botanists in the 18th century, and these diseases played a major role in the origin of plant pathology (the study of plant diseases) as a discipline separate from both botany (the study of plants) and mycology (the study of fungi). Today, specimens of the smut and bunt diseases serve as prime material for teaching students about the fundamentals of plant pathology. In addition, several of the cereal smuts have become valuable model systems for fundamental studies needed to understand fungi and fungal diseases of plants at the molecular level. However, because of the success in their control, and in spite of their widespread and still- expanding distribution, none of the species or strains of smut or bunt fungi currently known to affect cereals represent an unmanageable threat to agriculture in the world today. The investments of the United States and many other nations for most of this century in research on these diseases has resulted in successful disease control. Accordingly, and appropriately, work on these diseases has been mostly phased out over the past 20-30 years and the resources redirected towards development of the knowledge base and technology needed to control the many plant diseases still important or threatening to agriculture.
Cereal smuts and bunts, including Karnal bunt, require vigilance and justify continued research at some appropriate level like any disease of a food, feed, fiber or other crop. It should also be recognized that certain smuts or bunts continue to cause damage to cereals grown in some regions of the world as part of subsistence agriculture. While different countries may have different concerns for the potential of smuts and bunts to affect their cereal crops, nevertheless, the conclusions outlined above are based on fundamental principles developed from knowledge of the biology, epidemiology, and ecology of diseases that recognize no national borders.
Based on this information, the APS recommends that the U.S. Department of agriculture
For its role, APS will work through the International Society for Plant Pathology to enlist the international community of plant pathologists to