Herbicide spraying of cannabis

Herbicide spraying of cannabis is the destruction of growing cannabis by spraying it with herbicides, from aircraft or by hand, as a method of cannabis eradication. Governments took it up in the 1970s, when Mexico began spraying cannabis fields with paraquat from helicopters in late 1975. The large campaigns of the following decades were in Mexico, the United States, Colombia, Belize and South Africa. The herbicides were paraquat, 2,4-D and, increasingly, glyphosate. The United States government urged, equipped and in part paid for spraying in other countries, while at home courts stopped the federal spraying of paraquat in 1983.^: 20

Marijuana sprayed with paraquat in Mexico reached smokers in the United States. Congress barred American aid for such spraying from 1979 to 1981. Villagers in South Africa and Hawaii complained of sickness; Colombia's environmental agency objected to spraying in the national parks. Growers answered the spraying by moving their fields, making them smaller, hiding them among food crops or giving up cannabis for other crops.

Herbicides

Paraquat, a contact herbicide, killed a plant faster than any other then available. Mexico chose it in 1975 from a list of herbicides licensed in the United States for domestic commercial use. Mexico's poppy eradication, begun early in 1975, used 2,4-D; its helicopter campaign from late 1975 sprayed both herbicides.^: 8 Glyphosate, a systemic herbicide, acts through the leaves and roots and lacks paraquat's fast knockdown;^: 53 Colombia chose it over paraquat in 1984. South Africa used it after banning paraquat from aerial spraying in 1990.

In trials at the Newe Ya'ar experiment station in Israel, published by the United Nations in 1977, Menashe Horowitz sprayed commercial herbicides on young plants in glasshouses and in field plots; many killed or badly injured young plants, but only glyphosate, ioxynil and bentazon destroyed developed plants. A 1979 report of the United Nations Narcotics Laboratory on methods of destroying illicit crops rated glyphosate best of five herbicides tested and paraquat second. It recommended paraquat because glyphosate took longest to kill. Additives were also proposed: the 1978 American law exempted spraying done with a substance that warned users that marijuana had been sprayed. The 1981 law urged the President to spend at least $100,000 developing one. In Hawaii in 1990 the DEA mixed glyphosate with soap as a sticking agent and a red dye.

The United States and spraying abroad

Main article: United States and cannabis eradication abroad

From 1969, when a presidential task force urged that Mexico make the eradication of marijuana a national priority, the United States pressed producing countries to destroy their crops. From the mid-1970s it backed spraying from the air.^: 20 The State Department's Bureau of International Narcotics Matters told Congress in October 1983 that an American environmental impact statement published in December 1982 allowed it to support Western Hemisphere governments in using paraquat against cannabis. It hoped Colombia would adopt herbicides, which it had found "the most effective means of controlling narcotics throughout the world".^: 18 By 1987 the bureau supported more than 150 aircraft in Mexico, Colombia, Bolivia and Burma. It flew Thrush spray aircraft of its own in Belize, Colombia and Guatemala. It planned to urge Asian governments to use herbicides in their eradication campaigns.^{: 19–20, 26} The paraquat ban of 1978 to 1981, known as the Percy amendment, is described at Herbicide spraying in Mexico.

Campaigns

Main articles: Herbicide spraying in Mexico, Herbicide spraying in the United States, Herbicide spraying in Colombia, Herbicide spraying in Belize and Herbicide spraying in South Africa

Mexico

The Mexican attorney general's office and army sprayed cannabis and opium poppy with paraquat and 2,4-D from helicopters from late 1975, under the campaigns the DEA called Trizo and the Mexican government named Condor from 1977. DEA agents took part until 1978. United States appropriations for the aerial programme exceeded $150 million between 1977 and 1987; whether its money paid for spraying marijuana, or only poppy, is disputed.^: 8–9: 1

United States

Florida sprayed a marijuana field with paraquat at Red Bay on 28 August 1982. The DEA sprayed paraquat in national forests in Georgia and Kentucky in August 1983, until court orders and a consent judgment of November 1983 barred paraquat on federal land pending an environmental impact statement. Later federal spraying used glyphosate, among other places in Hawaii in 1990.

Colombia

The airwing of the Colombian National Police sprayed marijuana with glyphosate from July 1984, mainly in the Sierra Nevada de Santa Marta and the Serranía del Perijá, from helicopters supplied by the United States. By 1989 the traditional growing areas of northern Colombia were judged virtually free of cannabis.^: 32: 68

Belize

Two helicopters hired from Mexico sprayed paraquat over four districts of Belize in October 1983. Belize then stopped spraying, decided in 1985 against paraquat and resumed aerial spraying that October; from 1987 a regular programme assisted by the United States destroyed most of the crop.^: 35: 35

South Africa

The South African Police turned from hand cutting to herbicides in 1980 and to helicopters by the end of the decade, spraying the cannabis fields of the former Transkei, among other districts. Paraquat was banned from aerial spraying in 1990 and glyphosate used thereafter. The United States donated a helicopter and spraying equipment in 2004. The spraying of Mpondoland stopped in 2016.

Other spraying

• Guatemala. In May and June 1987 the State Department's aircraft and personnel carried out their first eradication campaign with the Guatemalan authorities against opium poppy and marijuana; the marijuana, perhaps 325 hectares that year, was "destroyed through chemical spraying".^{: 20, 38}
• Jamaica. The Jamaican government said in March 1985 that it would not spray marijuana fields with paraquat. In 1987 it destroyed about 60 per cent of its marijuana by hand and with backpack sprayers. The State Department planned to press it to begin aerial spraying.^: 28 In 1989 Jamaica used both manual and herbicidal methods.^: 69
• Morocco. Tom Blickman of the Transnational Institute writes that the Moroccan government increased eradication after 2003 with slash-and-burn campaigns and herbicide spraying, and that reports mention the use of Gramoxone, a brand of paraquat; one photograph shows young plants being sprayed in Taounate.
• Philippines. In September 2022 the Drug Enforcement Group of the Philippine National Police said that it had renewed the use of herbicides, spraying overrun plantation sites in Maguindanao so that fallen seed would not grow. It also sprayed in Maguing, Lanao del Sur, after a crop had been burned.
• Russia. Police in Primorsky Krai treated about one hectare of wild cannabis near the village of Romny with agrochemicals in 2017. In the Mak-2026 operation of 2026 they used herbicides sprayed from drones on wild cannabis in several districts.
• India. On 20 December 2024 police and the horticulture department in West Kameng, Arunachal Pradesh, destroyed about 0.7 acre of wild cannabis at Balemu with herbicide sprayed from a drone.

Health and the environment

Carlton E. Turner and his colleagues found paraquat in 20 of 160 samples of confiscated marijuana. In March 1978, 13 of 61 samples from the south-western United States were contaminated. Early in 1978 news stories alleged that the federal government was poisoning marijuana smokers on purpose. In the growing countries the complaints were about people, crops and water. In Belize in 1983 the Toledo Star reported paraquat on corn, beans and coconut trees and fear for the creeks people drank from.^: 36 In South Africa villagers told reporters that the spray drifted into their homes, made them ill and killed their maize. A toxicologist who monitored the police programme in the late 1990s said it had done no harm. Hawaii residents complained of nausea and breathing trouble in 1996, which a state official called "erroneous". Colombia's environmental agency, INDERENA, opposed paraquat and objected to spraying glyphosate in the national parks.^: 6 In March 2015 the International Agency for Research on Cancer classified glyphosate as a probable carcinogen. Colombia suspended its aerial spraying of coca after the finding. South African campaigners cited it in their challenge to the police spraying.

Effects on growing

The fall in Mexican marijuana after 1977, which American officials put down both to eradication and to American smokers' fear of paraquat, left a gap that Colombian growers filled; by 1981 Colombia supplied 79 per cent of the marijuana smoked in the United States.^: 30 A NORML organiser in California told Family Weekly in 1982 that the paraquat scare had been "the immediate impetus" for growing marijuana in the United States.^: 140 Within the growing countries, growers responded to spraying in several ways:

• fields moved higher and onto steeper ground, as in the Sierra Nevada de Santa Marta, or into the lower reaches of canyons;^: 32
• smaller fields, many of them, in place of a few large ones, in Colombia and in the American national forests;^: 32: 140
• cannabis planted among legitimate crops, moved to new regions or grown indoors, as in Colombia and Hawaii;^: 32: 6
• fields better hidden, as in Belize;^: 70
• harvesting before the spray could kill the crop, as in Mexico, which sent sprayed marijuana to market;
• bribes, in the Mexican Golden Triangle, for the helicopters to spray a grower's fields with water;^: 26
• and the abandonment of cannabis for other crops or trades: legitimate crops and coca in Colombia, cocaine trafficking in Belize.^: 68

In South Africa the spraying fell on poor growers of cheap, seedy dagga, which the journalist Kimon de Greef contrasted with the high-grade cannabis that police reports cited to justify it.

See also

• Herbicide spraying in Belize
• Herbicide spraying in Colombia
• Herbicide spraying in Mexico
• Herbicide spraying in South Africa
• Herbicide spraying in the United States
• United States and cannabis eradication abroad
• Yukthiya (eradication campaign)