Crops, too, are vulnerable. They are grown over very large areas (e.g., some 75 million acres for soybeans) and there is very little surveillance or monitoring. Likewise, plant diagnostic laboratories are scattered across the country and are underresourced and understaffed. In addition, great variability exists in the capabilities of these laboratories from state to state. This situation means that a long time could elapse from the introduction of a crop pathogen to its detection. Remote sensing, particularly satellite imagery, may have value in monitoring crops for disease outbreaks, including those resulting from bioterrorism.
Other factors heighten the vulnerability of U.S. crops: (1) many hybrid crop species exhibit low levels of genetic diversity; (2) there are few restrictions on trade, and large volumes of agricultural products are imported and exported each year; (3) a substantial proportion of the seed used for growing U.S. crops is produced in other countries, presenting a possible route for the introduction of dangerous plant pathogens as well as contaminated fertilizers and pesticides; (4) fungi, viruses, and bacteria cause more than 50,000 diseases of plants in the United States; (5) for any given crop, there are several pathogens that are not yet found in the United States but that cause major losses elsewhere; and (6) the biological agents that could affect crops are more numerous than the pathogens that affect humans, making it more difficult to focus the research funding available for efforts to counter agricultural bioterrorism.
Threats to crops intersect with threats to livestock in the case of animal feed, and there is a particular concern about the timing of ultimate effects. The delay between the time at which a bioterrorist contaminates animal feed and the time the human food product becomes adulterated would cause more uncertainty about the source of the contamination and could minimize the possibility of apprehending the terrorist. The less obvious and the more natural the source of biological contamination, the greater the likelihood that the contamination of the animal feed will be mistaken as a natural phenomenon. Rapid testing of feed and separation of contaminated feed are important steps, followed by the more specific identification of the contaminant to determine the source of adulteration and the possibility of decontamination. The development of specific antibodies for the production of sensitive and specific test kits is the key to identifying contamination. This would allow one to deal effectively with the disposal or decontamination of the animal feed and, ultimately, to prevent the contamination of animal-derived human food products (Von Bredow et al., 1999).
Rapid containment of agricultural pathogens is dependent on an effective system for diagnosis and the coordinated action of various state and federal agencies. Although these agencies, including USDA’s APHIS, have dealt successfully in the past with the natural introduction of several foreign pathogens of plants and animals, they are not properly organized to deal with the massive, multiple introductions that terrorists are likely to attempt. In essence, the game has changed, and this requires a substantial restructuring of the nation’s agricultural response systems.