Colombia: Herbicides versus market forces The Economist 11 April 1998 CSN Home | Environment

BOGOTA -- For the past four years, Colombia's anti-drugs police, backed by the United States, have tried to eradicate coca-growing in its southern jungles. Light aircraft and helicopters have dodged guerrilla bullets to spray nearly 90,000 hectares (350 square miles) of plantations. The result? In 1994 Colombians grew an estimated 45,000 hectares of coca; last year 80,000.

Critics are not surprised. As demand persists, so will supply. Growers simply plant more, to meet the risk--and if, even so, all of one farmer's crop is sprayed, that just means one more Colombian facing poverty and tempted to escape it by joining the local guerrillas. That is what you would expect, and, says a study from the National University in Bogota, it's what happens.

So drop the idea? Not at all. Instead, the sprayers are to try a new chemical. Till this year they have used glyphosate, spraying it as a liquid. This has drawbacks. It cannot usefully be done in strong rain or wind, and it requires pilots to fly very low, making them more vulnerable to sniper fire. Now a granular chemical is being considered, tebuthiuron--a broad-spectrum herbicide particularly effective against woody vegetation such as trees, shrubs and vines.

The environment ministry in 1994 advised against tebuthiuron, saying it might damage forests and contaminate ground-water. The present minister, Eduardo Vera-no, is against it. But he can be overruled. A rumour last week that spraying with tebu-thiuron was about to start set alarm bells ringing. In fact, only a only a trial project is under discussion. But this has opened a fresh debate on the chemical, supplied by Dow Agrosciences under the trade name Spike 20P. Its labelling shows why:

Do not apply Spike 20P near desirable trees or other woody species. Exposure of even a small part of a plant root system may cause severe plant injury or death--and "near", the label suggests, can stretch as far as 80 metres. Given the vagaries of aerial spraying, this would bar the use of tebuthiuron in many coca fields. There is also a lengthy section on the risk to ground-water supplies. The United States Environmental Protection Agency says tebuthiuron is very prone to leach into groundwater.

American officials cite studies done in their country as indicating that the chemical could not damage Colombia's forests. Colombia's vigorous police chief, General Rosso Jose Serrano, argues that the damage caused by farmers clearing land for coca far exceeds any risk from tebuthiuron. Colombia's National Drugs Council is in favour of the new chemical, as is its environmental auditor, Luis Eduardo Parra, who is appointed by the government to ensure that only the coca gets killed.

Dow itself is reluctant to see its product used in the Colombian rainforest. Mr Parra thinks this may reflect Dow's memory of the way the American government left it to pick up the legal fallout from the use of the notorious Agent Orange defoliant during the Vietnam war. But the company readily calls it "very risky" to apply tebuthiuron "where the terrain slopes, rain-fall is significant . . . and the application is made under less-than-ideal circumstances".

Recent talk of "Vietnamisation", based on creeping American involvement in Colombia's wars against both drug-traffickers and (sometimes the same people) guerrillas is far-fetched. But there are many who would argue that spraying coca plantations with herbicide--no matter which one--will prove about as effective a way to reduce cocaine output as defoliating the jungle was to defeat the Vietcong.

©1999 The Economist