Alachlor
Encyclopedia
Alachlor is an herbicide
from the chloroacetanilide family. Its mode of action is elongase inhibition
, and inhibition of geranylgeranyl pyrophosphate
(GGPP) cyclisation enzymes, part of the gibberellin
pathway.
s Alanex, Bronco, Cannon, Crop Star, Intrro, Lariat, Lasso, Micro-Tech, and Partner. It mixes well with other herbicides, and is found in mixed formulations with atrazine
, glyphosate, trifluralin
, and imazaquin. It is used mainly to control annual grasses and broadleaf weed
s in corn
(maize
), soybeans, and peanuts.
It is most commonly available as microgranules containing 15% a.i., or emulsifiable concentrate containing 480 g/ litre of a.i. Homologuation in Europe requires a maximum dose of 2,400 g per hectare of a.i., or 5 litres/hectare of emulsifiable concentrate or 17 kg/ha of microgranules. The products are applied as either pre-drilling, soil incorporated, or pre-emergence.
classifies the herbicide as toxicity class III - slightly toxic. The EPA has described the following effects when exposed to levels above the maximum contaminant level (MCL): slight skin
and eye
irritation; at lifetime exposure to levels above the MCL: potential damage to liver
, kidney
, spleen
; lining of nose
and eyelid
s; cancer
. Since 2006, use of alachlor as a herbicide is banned in the European Union
and atrazine
.
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
from the chloroacetanilide family. Its mode of action is elongase inhibition
Enzyme inhibitor
An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
, and inhibition of geranylgeranyl pyrophosphate
Geranylgeranyl pyrophosphate
Geranylgeranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of terpenes and terpenoids. In plants it is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls....
(GGPP) cyclisation enzymes, part of the gibberellin
Gibberellin
Gibberellins are plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence....
pathway.
Uses
It is marketed under the trade nameTrade name
A trade name, also known as a trading name or a business name, is the name which a business trades under for commercial purposes, although its registered, legal name, used for contracts and other formal situations, may be another....
s Alanex, Bronco, Cannon, Crop Star, Intrro, Lariat, Lasso, Micro-Tech, and Partner. It mixes well with other herbicides, and is found in mixed formulations with atrazine
Atrazine
Atrazine, 2-chloro-4--6--s-triazine, an organic compound consisting of an s-triazine-ring is a widely used herbicide. Its use is controversial due to widespread contamination in drinking water and its associations with birth defects and menstrual problems when consumed by humans at concentrations...
, glyphosate, trifluralin
Trifluralin
Trifluralin is a commonly used pre-emergence herbicide. With about 14 million pounds used in the United States in 2001, it is one of the most widely used herbicides. Trifluralin is generally applied to the soil to provide control of a variety of annual grass and broadleaf weed species...
, and imazaquin. It is used mainly to control annual grasses and broadleaf weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s in corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
(maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
), soybeans, and peanuts.
It is most commonly available as microgranules containing 15% a.i., or emulsifiable concentrate containing 480 g/ litre of a.i. Homologuation in Europe requires a maximum dose of 2,400 g per hectare of a.i., or 5 litres/hectare of emulsifiable concentrate or 17 kg/ha of microgranules. The products are applied as either pre-drilling, soil incorporated, or pre-emergence.
Safety
The United States Environmental Protection AgencyUnited States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
classifies the herbicide as toxicity class III - slightly toxic. The EPA has described the following effects when exposed to levels above the maximum contaminant level (MCL): slight skin
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...
and eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
irritation; at lifetime exposure to levels above the MCL: potential damage to liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
, kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
, spleen
Spleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
; lining of nose
Human nose
The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...
and eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
s; cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
. Since 2006, use of alachlor as a herbicide is banned in the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
Environmental Properties
Alachlor exhibits moderate sorption in soil, ranging from 43-209 mL/g. Photodegradation is a minor contributor to alachlor fate. Degradation in soil appears to be largely biologically mediated, and produces a number of metabolites. The half life in aerobic soil ranges from about 6 to 15 days, and is considerably shorter under anaerobic conditions. One possible explanation for the short anaerobic half life is the observation that alachlor is rapidly transformed under anoxia to up to 14 degradation products in the presence of iron-bearing ferruginous smectites. The iron in such minerals can be used by certain soil bacteria as an electron acceptor when soils are flooded, thus the process of herbicide transformation by reduced clay is thought to be microbially mediated. Similar observations have been reported for the herbicides trifluralinTrifluralin
Trifluralin is a commonly used pre-emergence herbicide. With about 14 million pounds used in the United States in 2001, it is one of the most widely used herbicides. Trifluralin is generally applied to the soil to provide control of a variety of annual grass and broadleaf weed species...
and atrazine
Atrazine
Atrazine, 2-chloro-4--6--s-triazine, an organic compound consisting of an s-triazine-ring is a widely used herbicide. Its use is controversial due to widespread contamination in drinking water and its associations with birth defects and menstrual problems when consumed by humans at concentrations...
.