Vegetation control, herbicides

The intensive chemical synthesis program on the pyridylimid-azolinone herbicides at the Agricultural Research Division of American Cyanamid resulted in the discovery of several important crop protection products (1-7). Among them are 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid 1 (AC 243,997, imazapyr) and its isopropylamine salt 2 (AC 252,925) registered by American Cyanamid as ARSENAL, ASSAULT and CHOPPER total vegetation control herbicides. 

Herbicide Glasses and Databases. Herbicides can be classified as selective and nonselective. Selective herbicides, like 2,4-D (2,4-dichlorophenoxyacetic acid), metolachlor [51218-45-2] and EPTC [759-94 ] are more effective against some types of plants than others, eg, broadleaved plants vs grasses. Glyphosate [1071 -83-6] is representative of the nonselective herbicides used for total vegetable control. 

Bromacil is a uracil herbicide introduced by du Pont in 1963 (Fig. 4). It controls a broad spectrum of weeds in citrus and pineapple crops. The chemical is also used for general vegetation control on noncrop areas such as railroads and industrial areas. 

The herbicide paraquat (l,l -dimethyl-4,4 -bipyridinium ion) is used widely in vegetation control programs. It is estimated that paraquat has been used in the United States on 10-12 million acres annually and is registered on 63 crops. Recommended rates vary from 0.25 to 1.5 Ib/acre. Human exposure should be limited during application, due to the toxic nature of paraquat. Most worker exposure studies (1-3) have addressed the issue of occupational body burden idien engaged in paraquat application with conventional spray equipment. Precautions taken to reduce respiratory and dermal routes of entry substantially lower the risk of potential adverse health effects. 

Class C turf is mowed two to three times per year, usually never fertilized but control of certain broadleaf weeds may occasionally occur when infestations become severe. The key objective with this mowing frequency is to cut down seedheads (which result in brown color) and excessive vegetation which may harbor unwanted animals. An example of this type of turf area would be highway roadsides and remote industrial sites. Type I, herbicide Type I and Type II PGRs can be used effectively all be used effectively. One pass of the spray boom along each side of the highway provides sufficient vegetation control without the possibility of overlap injury. 

AG) is used for weed control in grapes, nut crops, pome and stone fruits and also as a cotton defoliant [259], It was registered in Australia and approved by U. S. enviromnental protection agency. Benzfendizone (developed by FMC Corporation) is a post-emergence herbicide that provides good control of grass and broadleaf weeds in tree fruits and vines, as a cotton defoliant, and in total vegetation control [256], Flufenpyr-ethyl (developed by Sumitomo Chemical... 

Triazines. Triazine herbicides are one of several herbicide groups that are heterocycHc nitrogen derivatives. Triazine herbicides include the chloro-, methylthio-, and methoxytriazines. They are used for the selective pre-emergence control and early post-emergence control of seedling grass and broadleaved weeds in cropland (299). In addition, some of the triazines, particularly atrazine, prometon [1610-18-0] and simazine [122-34-9] are used for the nonselective control of vegetation in noncropland (2). Simazine may be used for selective control of aquatic weeds (2). 

Plants can also be pests that need to be controlled, particulady noxious weeds infesting food crops. Prior to 1900, inorganic compounds such as sulfuric acid, copper nitrate, sodium nitrate, ammonium sulfate, and potassium salts were used to selectively control mustards and other broadleaved weeds in cereal grains. By the early 1900s, Kainite and calcium cyanamid were also used in monocotyledenous crops, as well as iron sulfate, copper sulfate, and sodium arsenate. Prom 1915 to 1925, acid arsenical sprays, carbon bisulfate, sodium chlorate, and others were introduced for weed control use. Total or nonselective herbicides kill all vegetation, whereas selective compounds control weeds without adversely affecting the growth of the crop (see Herbicides). 

Each insecticide, fungicide, rodenticide, herbicide, or other pest control product must be registered with the State Bureau of Chemistry as an economic poison before being offered for sale in California. Registration may be refused, after hearing, for a product that is of little or no value for the purpose intended, or that is detrimental to vegetation (except weeds), to domestic animals, or to the public health and safety, when properly used. 

The major crops for agrochemical use are cotton, rice, maize, vegetables and top fruit for insecticides small grain cereals, rice, vines and top fruit for fungicides, and maize, soybeans, small grain cereals, rice, industrial weed control, plantations and orchards for herbicides. Other crops that may be of interest include sugar beet, oil-seed rape, potatoes and citrus dependent upon your company s presence in these crops. 

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