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09/01/98

Every plant is susceptible to disease. Narcotic plants such as the cocaine plant and opium poppy are  no exception. In most cases, a single disease causes minimal damage to a plant population, similar to  the effect of a common cold on humans. However, in a few cases such as Dutch Elm Disease and the Great Potato "Famine, the impact of a pathogen on a plant is devastating. Biocontrol research endeavors to find and develop plant pathogens that are capable of destroying unwanted plants such as noxious 
weeds or illicit narcotic crops. These agents have several requirements, including; specificity to a single host, lethality and the ability to be mass cultured and formulated in a laboratory. For example, a biocontrol agent for control of coca must only attack coca, not tomatoes, peas, bananas, etc. In addition, the biological control agent or mycoherbicide must not pose any risk to humans or to the environment.

1 ) Endemic to Andean countries

2) Non-toxic to humans and animals

3) Coca plant specific (does not attack non-host plants)

4) Long lasting (decades)

5) Wide area use will preclude slash and burn destruction of rain forest

6) Environmentally compatible with reclamation and sustainable agriculture

7) Superior alternative to chemical herbicides

In the mid 1980s, large numbers of coca plants were dying on a USDA research station in Kauai, Hawaii.  The fungal pathogen, Fusarium oxysporum f.sp. erythroxyli (FoxyE) was isolated from the diseased plants. It was subsequently found that this same disease was epidemic in many of the coca-producing areas of the Upper Huallaga Valley (UHV) in Peru and had been reported in Colombia and Bolivia. Press reports (LA Times, Miami Herald) estimate that this disease had resulted in coca crop losses of up to 70% in certain areas. Establishment  of this natural pathogen of coca in other cocaine producing areas could significantly reduce the supply of illicit cocaine. Thus, extensive research was undertaken to determine the feasibility of using this pathogen as a biological control agent for control of the cocaine plant.

Land in the Colombian Amazon is cleared for coca production by slashing and burning. It has been estimated that for every acre of coca bushes planted, growers burn four acres of jungle, due to the uncontrolled fire. Native plants that survive the fire are then killed by chemical herbicides eliminating plant competition for water and nutrients. PLANTE, a government program to develop alternative crops for coca and poppy growers, estimates that 200,000 gallons of herbicides are applied to Colombia's soil each year to clear the land for coca production. Many of these herbicides such as paraquat are highly toxic to humans and can cause ground water contamination. Coca growers have destroyed a portion of the Amazon rain forest equivalent to twice the area of Los Angeles in the past five years.

In addition, growers use 17.6 tons of fertilizer on coca fields and 100,000 gallons of insecticides to kill bugs feeding on the coca crop. These chemical pesticides are applied to coca fields by peasants who are unprotected from the toxic effects of the chemicals. Chemical poisonings are seldom reported due to the illicit nature of narcotic production.

After farmers abandon their coca fields, which are rapidly depleted by intensive coca cultivation, they move deeper into the jungle and establish new coca fields. The abandoned land is rapidly taken over by cattle ranchers preventing re-establishment of native species.

Processing coca leaves into the paste that is sold to drug traffickers requires outdoor laboratories where the leaves are mixed with cement, gasoline and sulfuric acid. PLANTE estimates that about a ton of chemical is needed to process the leaves from each acre of coca bushes. After the coca paste is made. the waste is dumped into the nearest river. This resulting water pollution has caused in a sharp decline in fish

The coca pathogen, FoxyE,. could mutate and attack other crops such as tomato, banana and cocoa.

Reality

Fusarium oxysporum is a complicated fungal species. The species is divided into plant pathogens and non-plant pathogens. The pathogens are further divided into forma specialis (or special forms) of F. oxysporum. Each forma specialis of Fusarium oxysporum only attacks a single species of plant or possibly a group of very closely related plant species. Over 100 different forma specialis of F. oxysporum have been described.

Each forma specialis of F. oxysporum is genetically isolated. Fusarium oxysporum is a sterile fungus meaning that it is not capable of sexual reproduction. Therefore, one forma specialis cannot combine with another to create a new pathogen. For example, the tomato strain of F. oxysporum cannot combine with the coca strain of F. oxysporum (FoxyE) to create a pathogen capable of attacking both coca and tomato.

Second, asexual recombination has not been detected between different forma specialis of F. oxysporum. Thus, the tomato strain of F. oxysporum cannot fuse with the coca strain of F. oxysporum to create a new pathogen.

Finally, there are many scientific reports that Fusarium oxysporum rapidly mutates. This statement is true, however, this adaptive process results in a loss of virulence not creation of a super pathogen. In order for a fungus to overcome all of a plant's defenses and cause disease, it must express numerous virulence genes. Without the entire complement of virulence genes, the fungus can not penetrate, survive or cause disease. In addition, these virulence genes are very specific and tightly regulated. Mutations which alter these genes disrupt the interaction between the pathogen and its plant host, impairing virulence or

survival of the pathogen. In other words, most mutations result in organisms that are incapable of competing and surviving in the environment.

Thus, there are many documented cases where a pathogenic F. oxysporum mutated and became a non-pathogen. There are not any known cases where a non-pathogen mutated and became a plant pathogen. In addition, there are no cases where the host range of F. oxysporum was greatly altered. For example, the tomato pathogen can not mutate into a banana pathogen, nor can a banana pathogen mutate into a tomato pathogen. This holds true of all the various forma specialis of Fusarium.

Most plant pathogens do not cause severe disease because it is not in their best interest to wipe out their host.

Genetic studies of plant pathogens have been undertaken by many laboratories in the United States and in the World to better understand the interaction of plant pathogens and their target hosts. All of these studies are done in strict containment in environmental growth chambers or laboratories.

Different isolates of the same pathogen frequently differ in pathogenicity.

Genetic studies frequently involve the comparison of these isolates in order to determine what genes are important for pathogenicity.

FoxyE strain En4 is an isolate from a dead coca plant in Hawaii. This strain is highly pathogenic to coca and will naturally wipe out coca plantations . As with most plant disease epidemics, they target cultivated crops, which are a relatively similar, or mono-cultures. Natural pathogens are going to be extremely effective on fields of cultivated coca, while native stands will likely be unaffected. There Genetic modification of this strain to enhance pathogenicity is not necessary.

Researchers hint that they took their cue for the development of a mycoherbicide for control of coca from a naturally occurring outbreak of the Fusarium wilt destroying crops in Peru's upper Huallaga Valley. However, press accounts allege a direct link between the DEA and the Peruvian epidemic.

Reality

The Peruvian epidemic of coca wilt is a naturally occurring event similar to other plant epidemics such as the Irish potato famine and Dutch elm disease.

Fusarium oxysporum was reported to have caused wilt of coca in South America as early as 1932. The incidence of the wilt increased sharply in the 1980's, coincident with the boom in coca production. This disease increase was most probably a result of intensive cultivation and establishment of large plantations of coca plants. As with all agronomic crops, the genetic diversity of the coca was rapidly minimized as growers only select certain plants for propagation creating a coca mono-culture. Historically, mono-cultures tend to be uniformly susceptible to a plant disease.

This recent wilt epidemic appears to have originated in a small area of the UHV of Peru and has rapidly radiated out to nearby coca fields. The disease has continued to spread throughout the UHV and has been reported in Colombia and Bolivia. This disease is spread by movement of infected plant material, infested soil, or infested water. The epidemic in Hawaii may have resulted from the importation of South American plants into the Kauai Research Station.

Allegations that this pathogen was deployed by the US government onto Peruvian coca fields are not consistent with the biology of the epidemic. The genetic diversity of the FoxyE isolates from diseased plants in Peru indicate that the epidemic is natural. There are at least two distinct sub-populations or vegetative compatibility groups of FoxyE in the UHV. The ratio of these two sub-populations varies widely from region to region. If this pathogen was introduced, there would not be multiple sub-populations and the ratio of the two groups would not vary from region to region. In contrast, all of the isolates from Hawaii belong to sub-population II, indicating this pathogen was introduced from infested plants, soil, or water.

Press reports (Miami Herald, LA Times, Covert Action Quarterly) state that Peruvian campesinos observed US helicopters dropping pellets of the fungus onto their fields and two-three days later, the coca plants wilted and died. This disease takes several months to develop and eventually kill coca plants. In addition, the epidemic is gradually moving outward from a few infection foci rather than occurring simultaneously within a large treated area.

The U.S. government will force South American governments to deploy FoxyE for eradication of coca.

The following national and international policies would effect deployment of this mycoherbicide:

UN Convention Against Drug Abuse & Trafficking obligates member states to eradicate illicit narcotic crops

Executive Order 12114 requires environmental review of US overseas pesticide application

All US research coordinated with technical division of UNDCP DOS/White House Scientific Policy Advisor requires foreign government consent to deploy herbicides

In accordance with the proceeding, FoxyE will not be applied without the agreement and cooperation of the governments of the producing nations.

This mycoherbicide will first be registered with the US EPA Office of Pesticide Programs. Requirements for this registration include tier one toxicity testing as well as, environmental risk assessment. In addition to the US EPA registration, the mycoherbicide will be registered with the government of the producing nation. Any additional testing requirements will be done prior to deployment.

The scarcity of registered mycoherbicides is not reflective of the magnitude of biocontrol research. There are numerous research laboratories, worldwide, with highly developed and effective biocontrol agents. Few biologicals are registered for control of weeds because they are often too host specific, development and registration is expensive, the potential markets for these products are limited, and the products must compete with broad-spectrum chemical herbicides. In addition, many of these products are-not attractive as commercial products because they are host specific and they work too well. Because a single application is effective for several years, if not decades, -it is more difficult to make the products economical. The biological control product for strangler vine, DeVine, was the victim of these exact circumstances. It simply worked too well