Pubdate: Sat, 11 Sep 1999
Source: New Scientist (UK)
Copyright: New Scientist, RBI Limited 1999
Section: This Week: Focus, Pg. 20
Contact:  http://www.newscientist.com/
Author: Kurt Kleiner

OPERATION ERADICATE

The US Is Turning To Biological Controls To Win The Drugs War. But They
Could Destroy Legal Crops As Well As Illegal Ones

FLORIDA'S law enforcement agents destroy about 100 000 marijuana plants
every year. And that's just 20 per cent of the estimated total grown there.
Many of the crops lie deep in the Everglades, where there is dense
vegetation to camouflage them and alligators to deter inquisitive state
officials. But last April, Jim McDonough, director of Florida's drug
control policy, decided to get tough. He suggested spraying the Everglades
with a fungus that would kill off the marijuana but leave other plants
untouched.

When the story appeared in newspapers in July, it enraged environmentalists
and provoked a lawsuit from a pro-marijuana group. Some critics described
it as a form of biological warfare. The "St Petersburg Times" urged that
the "killer fungus" should not be released. And several months before the
story broke, David Struhs, secretary of the Florida Department of
Environmental Protection (DEP), had expressed fears that the fungus would
mutate and attack other plant species.

McDonough's suggestion was based on research into biocontrol funded by the
US Department of Agriculture (USDA), aimed at finding a cheap and
environmentally friendly alternative to herbicides. The Florida office of
drug control policy now says both the media and the DEP had misunderstood
McDonough's proposal. He never suggested actually spraying the fungus over
the swamps, the office maintains, but merely wanted to test it in a
quarantine facility in Gainesville. Indeed, the DEP has since sanctioned
this proposal, but according to Albert Wollermann, the office's lawyer,
there are no immediate plans to go ahead with the tests.

Selective Killers

The Florida eradication scheme may have been shelved, at least temporarily,
but the USDA continues to spend dollar 23 million a year on research into
biocontrol agents that would selectively kill coca plants, from which
cocaine is derived, and opium poppies. And some of those are poised to move
out of the greenhouse and into the open.

Biocontrol of weeds is certainly not a new idea, but in the past it has
usually involved insects. The use of a fungus is not, however,
unprecedented. For the last 25 years, researchers have had varying degrees
of success in trying to control rush skeletonweed ("Chondrilla juncea"),
which affects wheat, with a fungus called skeletonweed rust ("Puccinia
chondrillina").

The fungus at the centre of the Florida row is a variety of "Fusarium
oxysporum". "Fusarium" species infect the vascular system of a number of
plants, from bananas to wheat, causing them to whither and die. The Florida
scheme was based on work carried out by a researcher at Montana State
University, Bozeman, called David Sands, who suggested that this particular
variant would be lethal only to cannabis.

Sands did initially have a grant from the USDA to look at using " Fusarium"
to control marijuana. But when he approached the Florida state government
it was as head of his own company, Ag/Bio Con. The USDA says it stopped
funding his research a few years ago, when lab tests showed the fungus was
only marginally effective against cannabis. "The results were mediocre,"
says Eric Rosenquist, leader of the USDA's international programmes, who
oversees the agency's funding for narcotics biocontrol, "If it's that
mediocre in the greenhouse, it's unlikely to work in the field."

Sands would not speak to "New Scientist". But his company continues its
research in this area. And recent evidence suggests that he has improved
the technology. Before the story broke in July, John Masterson, director of
the Montana office of the National Organization for the Reform of Marijuana
Laws (NORML), received an anonymous e-mail informing him of the Florida
proposal and the Montana research. He promptly phoned the university, which
confirmed that the research was taking place. But it refused to say more,
explaining that its policy was not to disclose results before publication.
NORML sued, and in August, before any judgment was handed down, the
university began to release documents relating to the research. In some,
Sands discusses patent applications he has made on a process for "virulence
enhancement" of bioherbicides. It's not clear what this enhancement
consists of, but in a letter he says that he developed it after USDA
funding stopped.

In the meantime, the USDA is collaborating with the UN on a programme at
the Institute of Genetics in Tashkent, Uzbekistan. They hope to use the
"Pleospora papaveracea" fungus to control opium poppies. But its main
effort is concentrated on another variety of "Fusarium oxysporum" that
attacks coca plants.

This fungus was discovered accidentally when it wiped out a test plot of
coca being grown in Hawaii. Since then, USDA researchers have worked on
manufacturing large amounts of the fungus in a form that is easy to store.
More importantly, they have assured themselves that it will attack only
coca plants. Since most pathogens evolve with their hosts, they can often
survive only in that host. This selectivity can be confirmed in the lab by
trying to persuade a fungus to infect first close relatives of the target
plant, then progressively more distant relatives, until researchers are
convinced no other plants will be affected. "We've done host specificity
studies," says Rosenquist of the anti-coca fungus. "We're convinced of its
safety. We're actually at the point now where we couldn't go any further in
the greenhouse."

In the case of cannabis, even the most rigorous host specificity studies
will not reassure some people. If the anti-cannabis fungus is now more
effective, it could spell disaster for farmers who grow industrial hemp.
These varieties of "Cannabis sativa" end up as vegetable oil or fibre and
can be grown legally because they are low in delta-9-tetrahydrocannabinol
(THC), the active component of cannabis.

Masterson points out that Montana, where some of the work on the fungus has
been done, borders the Canadian province of Alberta, where hemp has been
grown industrially since 1998. If the fungus somehow spreads to fields in
Alberta, it could damage the legal crop.

"For the hemp industry, it would be devastating for the fungus to get out,"
says Douglas Brown, a director of the WestHemp Cooperative in Vancouver,
British Columbia. "There would be millions of dollars of losses. If this
fungus is looking for "Cannabis sativa", it's not going to differentiate
between high-THC and low-THC varieties."

And even if the fungus stays put, it could destroy wild cannabis that has
adapted to conditions in the areas where it is released. Losing the wild
plants could make it harder to breed hemp with the traits future farmers
will need, says Brown.

But Rosenquist says the real question is not whether a fungus will spread
uncontrollably, but whether it will work at all. "The biggest problem with
classic biocontrol is when you release it into a complex ecology," he says.
"What may work well in one place may not work in another."

So the next step for the USDA will be to convince the government of one of
the coca-producing nations - such as Peru, Bolivia or Colombia - to let
field experiments take place there. But Pat Mooney, executive director of
the Rural Advancement Foundation International in Winnipeg, says using
biocontrol agents against narcotics crops is "agricultural terrorism,"
especially if it is done without the consent of the target country.

And according to "The Miami Herald", some Peruvian farmers think that this
has already happened. They have accused the US of testing an anti-coca
fungus that has since spread to bananas, yucca and tangerine crops.

Rosenquist denies this. And he stresses that work won't start without
permission from the country concerned. But even with the country's consent,
says Mooney, it's dangerous. "The solution to narcotics is not just to
destroy the crops. It's a fundamental social problem, and it's not going to
be solved by a silver bullet from an airplane."
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