Bogota, Colombia — Can you reduce world supplies of drugs by simply digging up, or spraying with chemicals, the plants that produce them - opium poppies, coca bushes, and marijuana?
Yes, you can. But. . . .
Producing countries need persuading - and help. Some do not control all the growing areas within their borders. And they are reluctant to upset their own farmers and their traditional ways of earning a living.
Not even the United States government has been able to start what has been regarded as the most effective eradication of all, widespread aerial spraying. And what works in one country will not necessarily work in another. Close one gate, and others open.
For all the efforts so far, vast acres of poppies and coca plants remain untouched, far more than necessary to meet legal world demands.
The Reagan administration remains convinced, however, that eradication is an essential tool in the overall struggle against drugs, no matter how many obstacles stand in the way.
The most promising new development is a November 1983 pledge by Italy to provide $40 million over the next five years to tackle coca cultivation in the Andes. Details are not yet worked out, but the pledge will almost double the $9 million a year budget of the United Nations Fund for Drug Abuse Control (UNFDAC).
Some United Nations drug officials in Vienna would like the US to use its Landsat infrared earth satellites to map all poppy-growing areas. US Assistant Secretary of State Dominick L. Dicarlo refused to comment on grounds of national security.
''We know where [the poppy] is,'' he added tersely. ''The problem is to get rid of it.''
In the late 1970s, Mexico showed what could be done. It sprayed more than 20, 000 acres of poppy fields with the herbicide paraquat and with aid from the US that reached $94 million in a decade. The US is increasing its commitment to destroying poppy growing in Mexican fields. In just two years, US annual aid to Mexico jumped from $1.3 million (1973) to $16 million (1975).
As a result, Mexico's share of heroin illegally smuggled into the US dropped from 87 percent in 1975 to 36 percent by 1981. US officials note, however, that poppies are being grown in smaller fields in and among rows of corn and other crops in the hope of avoiding aerial spray.
The Mexican government controls all of its own territory. By no means all producing countries can say the same. And none of them have all the planes and chemicals they would need to do the job.
Colombia, for example, claims it dug up 8.5 million marijuana plants in 1982, and 19.7 million coca bushes. Facing guerrilla insurgents in the north and east, and a powerful drug lobby, it has barely scratched the surface of its marijuana and coca cultivation. It has managed no aerial spraying of marijuana at all.
Peru's coca leaves provide almost half the cocaine consumed in the US. But Peru has yet to start significant eradication in the huge upper Huallaga Valley in the Andes. Some 7,000 farmers raise one-quarter of the world's supply there.
All its eradication programs so far have been voluntary. The US wants them to be compulsory, but faces farmers unwillingness to reduce their income and a government desire to find new legitimate markets for the coca leaf as a way of earning hard currency.
Bolivia has just agreed to a US-supported program for the first time, but little significant action has taken place.
''In the Andes regions of South America, it would take $100 million every year for the rest of the century to make a tiny dent on the huge coca-bush areas ,'' a Mexican official says gloomily .
In fact, Peru and Bolivia are already in violation of the 1961 international convention on narcotics. Under its provisions, both governments should by now have reduced coca-bush cultivation to traditional, native usage. By 1989, all cultivation is supposed to cease - something that the briefest glimpse of the Andean forests indicates cannot be done.
UN officials are aware of the situation. They keep a low profile in order to retain some leverage over the two countries.
In Thailand, the US is openly disappointed that, as Assistant Secretary Dicarlo put it, the Thais have so far ''failed to control the opium poppy. . . .''
One way Washington could encourage other countries to eradicate is to set a better example itself. But it has run into a series of problems.
In the very country that urges others to spray and dig up, marijuana was illegally grown in 1982 on 6,200 separate plots on 1,534,000 acres of national forest land. Illegal growers in the US guard their plots with guns, dogs, and hand grenades activated by trip wires, according to Drug Enforcement Administration (DEA) officials. Growers choose federal land because they cannot be made to forfeit land they do not own as a punishment. Unless they are caught on the land they can claim they have no connection to it.
But no sooner had agents sprayed small areas in Georgia and in Kentucky with the herbicide paraquat in August 1983 than a pro-marijuana lobby group, together with the Sierra Club, asked for a federal court order against it. The protesting groups claimed environmental damage and health hazards to anyone who smoked sprayed cannabis leaves.
The DEA replied that in 1982, 10.7 million acres of US farmland were sprayed with it, including crops of fruit, asparagus, alfalfa, corn (maize), lettuce, melons, peppers, sorghum, sugar beets, tomatoes, barley, and wheat.
Federal Judge June Green ruled in November this year that the federal government must submit an environmental impact statement before spraying with paraquat could resume.
Kevin Zeese of the National Organization for the Normaliztion of Marijuana Laws said, ''This kills spraying for at least two years.''
Robert Feldkamp of the DEA disagreed, saying the impact statement could be filed by next spring or summer.