The Farm Offensive: The Vulnerability of America’s Food Sources

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By Evan Thompson, Columnist

Typically when referring to biological weapons security, experts mean any organic agent with the capacity to harm or kill humans, but some target plants or animals instead. While these would not directly cause human casualties, an adversary could use these weapons to target a nation’s food supply, causing untold economic damage and food shortages. Foot and mouth disease and Karnal bunt are two examples of animal and plant bioweapons. While they do not harm humans, they have the capacity to cripple US agriculture if used by a hostile actor.

Foot and Mouth Disease (FMD)

FMD is a viral disease that targets cloven-hoofed animals and is endemic to most of the world. Foot-and-mouth disease virus (FMDV) is an RNA Aphthovirus with a high level of genetic diversity. As an RNA virus, strains and serotypes of FMDV are constantly mutating, making it very difficult to achieve any level of long-standing immunity. Even with vaccination, animals can only attain immunity for several months to a few years at best.[1]

FMDV is the most infectious disease known to man. It primarily affects cloven-hoofed animals such as cows, pigs, or sheep. FMDV resides in all secretions and excretions of infected animals, but is also exceptionally adept at aerosol transmission. Pigs are ideal hosts for producing this aerosolized form of the virus. A single pig can create and exhale enough virus particles per day to infect 100 million cattle.[2] A single virus can travel as far as 170 miles on the air in cool, humid environments.[3] In addition to its highly infectious nature, FMDV can replicate and transmit to a large degree before initial symptoms begin to appear on the infected animal. Due to these factors, the rate of infection is often 100%.[4]

When an outbreak occurs, the only solution is the quarantine and eradication of all infected animals as well as any that FMDV could have infected. This means ring culling, or the systematic eradication of animals in a given area. Some veterinarians advocate ring vaccination as a potential solution, but countries labeled FMD-free without vaccine have the greatest access to markets. Given the high genetic diversity and mutability of the disease, any immunity from vaccination would only be temporary, so the risk of infection often outweighs the perceived benefits. Eradication and carcass disposal carries its own risk, however, because any disposal sites would create toxic waste “superfund” sites for years to come.[5]

Karnal Bunt

Karnal bunt is a fungal disease that affects most kinds of wheat. Tilletia indica causes the disease, a fungus that infects the kernels of the wheat causing decreased productivity and lower quality. The hallmark symptoms of Karnal bunt are the unpalatable taste and the fishy odor from the kernels, which outwardly display a black and shriveled husk from the seed’s rupture during the spread of the teliospores. This generally happens during the harvest and handling of the wheat. As it is a fungus, there are no vaccines or preventative treatments.[6]

The fungus is highly survivable, resistant to both natural environmental factors and most fungicides. Once the fungus enters the soil, it persists for at least five years and longer in the seed. It can also survive the digestive tract of animals meaning growers cannot use the infected wheat as animal feed without extensive treatment. It thrives in temperate climates, and cool and wet conditions will catalyze the creation and spread of its spores. Once the plant is infected, it is extremely difficult to detect. Aside from the decrease in yield, the outward appearance of the plant is indistinguishable from a healthy plant. Furthermore, Karnal bunt is similar to other crop diseases, especially other bunt diseases.[7]

Karnal bunt is on most international quarantine lists. In the United States, the United States Department of Agriculture (USDA) regularly surveys grain at collection and co-mingling locations such as county elevators or feed mills. If the USDA detects the bunt, they quarantine the area until they no longer detect it in the soil. The government provides compensation to farmers in the area for every year under quarantine.[8]

The Threat

The use of non-human biological weapons is not operationally useful for terrorists since these diseases do not cause direct human casualties. Causing economic damage is a strategy that has never proven successful for terrorists.[9] What is more likely is a threat from an aggressive state with an interest in damaging an adversary’s economy.[10] While terrorist organizations would find the difficulty of credit claiming a problem, most states would appreciate the anonymity this weapon afforded as a way to protect against retaliation.

The weaponization of these diseases is simple and often as easy as spreading spores or freeze-dried infected meat.[11] Only a small number of states could perform this attack without harming themselves, however. Any attack on the US food supply would cause massive shocks in the food market, as The United States is the world’s largest producer of beef, second largest exporter of beef, and the second largest producer of pork.[12] It is also the world’s largest exporter of wheat, accounting for nearly a third of all wheat exports every year.[13] States, such as China, that have high levels of food independence also have insulation from such shocks, making agriculture bioweapons suitable tools.[14]

Conclusion and Recommendations

The effects of an outbreak of one or both of these disease would be devastating, with low estimates of approximately $33 billion, but more realistic estimates reach $800 billion.[15] To counter these threats, the government must develop rapid detection tests. Currently, outbreak detection is slower than necessary; a devastating fact considering the USDA estimates the cost of containing FMD would cost $3 million more for every hour undetected.[16] Likewise, the difficulty in detecting Karnal bunt makes it a priority, but the government should also put resources toward developing and approving a fungicide that is effective against Karnal bunt. With these developments, the United States would not be able to stop an attack, but the damage would be far lower.


Evan Thompson is a second year Master’s student of Security Studies at Georgetown University where he concentrates in Unconventional Weapons and Nonproliferation. He began his career in nonproliferation while an undergrad studying International Affairs at the University of Georgia. In his senior year, he worked with the Center for International Trade and Security as a Security Leadership Fellow. The research he conducted at CITS on strategic trade control violations led to his next fellowship with the Bulletin of the Atomic Scientists as a Leonard M. Rieser Fellow. He continued his work in nonproliferation this summer at the State Department’s Office of Export Control Cooperation, and he transitioned to the non-profit CRDF Global in September. He will graduate from Georgetown in Spring 2015 and hopes to continue in the field of nonproliferation and international security in the future.


[1] “Foot-and-Mouth Disease: Fiebre Aftosa Technical Factsheet (Foot and Mouth Technical Factsheet).” Center for Food Security and Public Health, Iowa State University. (2007), p. 1.

[2] Frank Barnaby, How to Build a Nuclear Bomb and Other Weapons of Mass Destruction, New York: Nation Books (2004), p 47.

[3] “Foot-and-Mouth Disease.” Center for Infectious Disease Research Policy (CIDRAP), (2012).

[4] “Foot and Mouth Technical Factsheet,” 2.


[6] “Karnal Bunt: A Fungal Disease of Wheat,” Animal Plant Health Inspection Service Industry Alert (APHIS), (July 2001), p.1.

[7] “Karnal Bunt,” Department of Environment Food and Rural Affairs (DEFRA), pp.2-3.

[8] APHIS 2

[9] Benjamin Cole, The Changing Face of Terrorism: How Real is the Threat from Biological, Chemical and Nuclear Weapons? London: I. B. Tauris (2011), pp. 75-80.

[10] Elizabeth L. Stone Bahr, “Biological Weapons Attribution: A Primer,” Naval Postgraduate School, June 2007, p. 4.

[11] O.N. Fellowes, “Freeze-Drying of Foot-and-Mouth Disease Virus and Storage Stability of the Infectivity of Dried Virus at 4 C,” Applied Microbiology, May 1965; 13(3): 496–499.

[12] “Animal Production,” United States Department of Agriculture, June 16, 2014.

[13] “Wheat- Trade,” USDA Economic Research Service, January 24, 2013.

[14] David Stanway, “China Needs to Import More Food to Ease Water, Energy Shortages: Official,” Reuters, July 28, 2014.

[15] Robert A. Heckert and Joseph P. Kozlovac. “Biosafety Levels for Animal Agriculture Pathogens.” Applied Biosafety. (2007). 169.

[16] Steve Wampler, “Scientists develop rapid diagnostic test for foot-and-mouth and six other livestock diseases,” Lawrence Livermore National Lab, May 25, 2005.

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