Fungi May Be the Newest Recruits in War on Drugs

The next weapon in the arsenal of the war against drugs may well be biological.

Scientists have discovered three microscopic fungi that will cause marijuana plants, opium poppies and coca bushes to turn yellow, drop their leaves and wither.

While opponents believe that use of such fungi could cause an environmental disaster, supporters see it as a benevolent alternative to fumigation, which defoliates all plants--including food crops--underneath the fine mist sprayed by planes.

As President Clinton visits Colombia today to formally initiate a controversial $1.3-billion anti-narcotics aid package, the potential use of fungi is becoming an important part of the debate over the most effective way to halt drug production and trafficking. Colombia is the world’s leading producer of cocaine.

“It was a godsend,” said a U.S. official who saw the effects of an anti-coca fungus in Peru’s Upper Huallaga Valley at the beginning of the 1990s. The fungus wiped out 30% of the coca crop, and the leaves that survived had lower levels of alkaloid, the active ingredient in cocaine, says the official, whose life has been threatened because of his anti-drug work.

The fungus strangles plants by blocking their vascular systems, much like cutting off a person’s blood supply.

But ecologists worry: What happens afterward?

“It could have an impact on other vegetation when it finishes off the coca,” said a Colombian government biologist. “This is a living organism that will transform itself in order to survive. Field tests are a risk for Colombia and the entire Amazon basin.”

With that argument, Colombia--like Florida, which is a significant marijuana producer--has refused to permit field testing of anti-drug fungi. But laboratory testing continues in controlled environments as far flung as Uzbekistan and Hawaii.

Biologists are concerned that the Colombian government, recipient of two-thirds of the funds in the U.S. anti-drug aid package, will not be able to resist pressure to test the anti-coca fungus outside the laboratory. “We say ‘no,’ but then it turns out to be ‘yes,’ ” warned agronomist Pedro Leon Gomez.

The anti-coca and anti-marijuana fungi are cousins in a family that is the plant world’s equivalent of the Jesse James gang. Members of the Fusarium oxysporum clan have ravaged cotton in Australia, muskmelon in California, beans in Spain and even carnations and banana trees in Colombia.

However, each fungus is choosy about its victim, experience indicates, generally preferring to attack only one species of plant. The fungus that destroyed the carnations here did not bother other flowers, and the strangled banana trees were replaced by another variety, an effective but expensive solution.

But scientists are still experimenting to figure out how adaptable each fungus can be in different soils and climates.

Since the fungus lives in the soil, it goes about its deadly work despite rain or wind, a major advantage over pesticides.

The drawbacks of other eradication methods may be one of the factors that will make biological methods more tempting. During the past two years that U.S. Defense Department contractors have been spraying pesticides on Colombian coca fields, production has actually risen by half.

Nor have efforts to persuade coca farmers to grow other crops been particularly successful.

“Gains in establishing alternative crops were modest in the extreme and worse yet when it came to eradication of drug crops,” according to an Inter-American Development Bank, or IDB, evaluation of projects in Colombia from 1991 to 1996.

There are few indications of a major improvement in the past four years, despite the availability of a $90-million IDB credit for such projects. Only $28.5 million of that money has been used, according to Colombian officials, because the credit requires matching funds and the government here has not provided enough.

Still, a Colombian government biologist wary of the fungus insisted: “This should only be considered if it were the last option available. Have we tried all the other options?”

The fungus could undermine a potentially viable option that has not yet been tried, warns agronomist Leon Gomez. Oil palms are among the few cash crops that will grow in the same climate as coca.

Although hardly as profitable as illegal crops, palm oil does have a guaranteed market, says the Cornell-educated Leon Gomez, who heads the oil palm industry’s research institute here. The institute’s main project for the past decade--$8 million worth of research--has been to find a way to protect palm trees from a soil fungus.

Referring to Fusarium oxysporum, he said, “This fungus is much more aggressive than the one we are trying to manage now.”

In fact, among the fungus family’s best-known victims was the palm oil industry in Nigeria and Zaire.

Leon Gomez says he could not in good conscience recommend that oil palm farmers plant in a zone that was known to have been infested with even a distant relative of that fungus. “The risk is just too high,” he said.

Florida officials came to the same conclusion about the anti-marijuana cousin, prohibiting its use there last year. Their main concern was that the fungus might mutate and attack other crops.

As work on the anti-marijuana and anti-coca fungi has stopped short of field testing--U.S. and U.N. officials insist that a naturally occurring strain is at work in Peru--research on an anti-poppy fungus from a different family has begun to catch up.

The Institute of Genetics at Tashkent, the capital of Uzbekistan in Central Asia, has tested Pleospora papaveracea on 150 plants closely related to the opium poppy, from which heroin is derived, and has not yet found another that the fungus harmed.

“The basic science is done or close to being done,” said Howard Stead, chief of the scientific section at the U.N. International Drug Control Program, which sponsors the research.

Native to Uzbekistan, the fungus “has different rates of effectiveness, depending on variables such as climatic conditions,” he said.

The fungus still needs to be tested in areas where illicit crops grow, he says.

Both Colombia and the United States use biological controls against pests that attack commercial crops, he says.

“We’re talking about similar technologies, whether they are opium poppies or coca bushes or weeds,” he said. “When you are killing coca bushes, there are interest groups that want to protect the coca bushes, so questions are raised.”

However, one of the Colombian biologists says experiences with biological controls are exactly what have prompted his government’s objections to introducing a fungus.

“We introduced one ant to control another ant, and now the [new] ant is a worse problem,” he said, citing one example. “They ate the first ants, and now they eat everything those ants ate.

“The fungus would not know why we brought it here or when it had finished its job,” he added. “We are trying to turn responsibility for a problem of [drug] consumption into a biological problem. Since we as humans cannot solve this problem, we want a fungus to solve it for us.”