defoliant


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Related to defoliant: paraquat, Agent Orange

defoliant,

any one of several chemical compounds that, when applied to plants, can alter their metabolism, causing the leaves to drop off. In agriculture defoliants are used to eliminate the leaves of a crop plant so they will not interfere with the harvesting machinery. Their main military objective is to deprive the enemy of cover. In addition they have been used on food crops that have been considered potential sustenance for the enemy. Unfortunately, defoliants are not discriminating chemical weapons. Normally applied from the air, they are difficult to confine to a desired area and may thus contaminate watercourses, with disastrous effects on fish and other aquatic life. Human beings are also known to suffer toxic effects from them. Further, indigenous populations have suffered severe malnutrition when their food crops have been defoliated to prevent their use by the enemy. Possibly the severest and most long-lasting side effect of military defoliation is the disruption of the fragile jungle ecosystem. Contrary to appearances, the soils that underlie rain forests are not abundant in plant nutrients. Therefore, the ecosystem generally conserves and recycles the nutrients that do exist. Any massive disruption, such as killing or interfering with the metabolism of large numbers of plants, inevitably causes large amounts of nutrients to be washed away by rainfall. Also, when sunlight, which would normally be blocked by the leaves, falls on the claylike soil of the jungle, the soil bakes and becomes very hard. These conditions operate against reestablishment of normal vegetation. During the Vietnam War, U.S. forces used the defoliant Agent OrangeAgent Orange,
herbicide used by U.S. forces during the Vietnam War to expose enemy guerrilla forces in forested areas. Agent Orange contains varying amounts of dioxin. Exposure to the defoliant has been linked with chemical acne, non-Hodgkin's lymphoma, Hodgkin's disease,
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, which is widely thought to have led to cancer and other side effects among military personnel and civilians.

defoliant

[dē′fō·lē·ənt]
(materials)
A chemical sprayed on plants that causes leaves to fall off prematurely.
References in periodicals archive ?
There is still a considerable amount of soil contaminated by the dioxin-containing defoliants sprayed by the US Army during the Vietnam War.
Defoliants that contain horticultural vinegar can be used in place of agricultural chemicals--some of them confirmed carcinogens--that harm wildlife, pets, and people.
Like Hung Duc, Khanh is believed to be a victim of Operation Ranch Hand, the United States military's effort during the Vietnam War to deprive the enemy of cover and food by spraying defoliants.
Jon Mitchell, 39, from Sand-fields, Swansea, has for many years covered the alleged existence of the toxic defoliant on Japan's Okinawa island and issues surrounding US military bases there.
Swansea-born Jon Mitchell, pictured, has made allegations on Japanese TV and in publications including the Japan Times that defoliants including Agent Orange were buried in Okinawa following the conflict and that they continue to pose a massive threat to health.
American planes sprayed millions of gallons of the toxic defoliant over jungle areas to destroy enemy cover.
The base was a key site in the US defoliant program during the Vietnam War, and much of the 80 million litres (21 million gallons) of Agent Orange used during "Operation Ranch Hand" was mixed, stored and loaded onto planes there.
The incumbent will develop an imaging system that can perform remote sensing operations on the agricultural aircraft and the ground on-the-go platform, which will fuse the information from visible and near infrared (VNIR) imagery, thermal imagery and measurements of field variables such as soil texture, crop water stress, the effects of plant damage from off-target herbicide drift, and plant vigor to determine where to apply growth regulators and cotton defoliant. Knowledge of remote sensing and geographic information system (GIS) methods for spatial and spectral analysis of crop stress caused by multiple factors are desirable.
Agent Orange is a defoliant containing dioxin that the US used during the Vietnam war.
Introduced by French colonists, and soon exploited by international businesses including the French tire company Michelin, Vietnamese rubber trees were decimated by Agent Orange, a substance used by the American military as a defoliant in an attempt to deprive the Vietcong of ground cover.
My ephemeral office was a former war zone and our camp had no trees because some 40 years earlier it had been stripped bare by that destructive defoliant, Agent Orange.
Almost 2.6 million men and women serving during the Vietnam conflict were exposed to Agent Orange, a chemical defoliant. After they began to experience a wide variety of medical problems, including type 2 diabetes, prostate cancer, multiple myeloma, and chronic lymphocytic leukemia, it was presumed that Agent Orange exposure was the cause.