A few months after the biological attacks of small pox and anthrax through the mail system, the agricultural supplies into America comes under attack. Spinach from California becomes contaminated with E-coli. Apples from Washington State become contaminated with E-coli. Beef from Texas becomes contaminated with Mad Cow.
America does not detect this as a form of form of agricultural terrorism since it is occurring with US boarders and in different locations throughout the US. It is actually caused from the migrant workers that are in America illegally working in the fields. Some of these workers are actually associated with Hezbollah and not Mexican and spread the viruses on the crops unknowingly to their supervisors.
It is assumed that it is just a coincidence that is occurring at this time. Moreover, there are no deaths associated with these attacks. More so, these attacks backfire on the intentions of the terrorists. Since it damaged the spinach crops from California, the Apples from Washington and the Beef from Texas and did not kill anyone. Americans just bought their food supply from elsewhere. Americans purchased beef from Chile, Spinach from Mexico, and Apples from Russia. This in turn shortened the food supply from countries that needed it more. Therefore the less developed countries that needed the food could not afford to stay in a bidding war for food against America. It did not hurt the American economy or food supply.