Nonselective 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. 

Although the ratios have varied from year to year since 1979, the selective herbicides used in com production have accounted for approximately 21% of herbicide use on a per crop basis (24). Herbicide use in soybean and cotton production combined account for ca 23% of the selective herbicide market. Graminicides, which selectively kill grasses, constitute 40% of the total market, leaving a market share of approximately 16% for the nonselective herbicides. 

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). 

Uses. The largest usage of PCl is to produce phosphonic acid, H PO, which in reaction with iminodiacetic acid and formaldehyde forms a glyphosate intermediate that is decarboxymethylated to glyphosate, an effective nonselective herbicide (see Herbicides). Phosphoms trichloride is also a convenient chlorinating reagent for producing various acyl and alkyl chlorides. 

Ammonium sulfamate is highly effective in nonselective herbicides to control weeds, bmsh, stumps, and trees (58) (see Herbicides). 

Approximately 5% of the U.S. consumption of is in agriculture. Boron is a necessary trace nutrient for plants and is added in small quantities to a number of fertilizers. Borates are also used in crop sprays for fast rehef of boron deficiency. Borates, when apphed at relatively high concentration, act as nonselective herbicides. Small quantities of borates are used in the manufacture of alloys and refractories (qv). Molten borates readily dissolve other metal oxides usage as a flux in metallurgy is an important apphcation. Other important small volume apphcations for borates are in fire retardants for both plastics and ceUulosic materials, in hydrocarbon fuels for fungus control, and in automotive antifreeze for corrosion control (see Corrosion and corrosion inhibitors). Borates are used as neutron absorbers in nuclear reactors. Several borates, which are registered with the Environmental Protection Agency (EPA) can be used for insecticidal purposes, eg, TIM-BOR. 

Nonrepairable components, in reliability modeling, 26 989 Nonruminant feeds, 10 836-847 additives to, 10 846 ingredients of, 10 837-838 swine and poultry nutrient requirements, 10 838-845 Nonselective catalytic reduction (NSCR), 10 101-102 17 184 19 626 Nonselective herbicides, 13 313 Nonselective poisoning, 5 258 Nonself-aligned (NSA) HBT fabrication, 22 167... 

Paraquat and the related chemical diquat are nonselective herbicides that are also toxic to mammals. Occupational or accidental exposure to paraquat can be from oral ingestion, dermal exposure, or inhalation, all of which can cause serious illness or death. While seldom used in the United States, paraquat is still widely used in developing countries. At one time it was used to kill marijuana plants, but a number of fatalities were observed when marijuana contaminated with paraquat was inhaled. 

Glyphosate is a nonselective herbicide that affects a biochemical process common to all plants—the biosynthesis of the amino acids tyrosine and phenylalanine. Glyphosate has low toxicity in animals because most animals do not synthesize these amino acids, obtaining them from food instead. Glyphosate is the active ingredient of the herbicide Round-up. 

Herbicide activity is either selective or nonselective. Selective herbicides are used to kill weeds without significant damage to nearby plants. They are used to reduce weed competition in crops, lawns, and ornamental plantings. Nonselective herbicides are chemicals that kill all plants present if apphed at an adequate rate. They are used where no plant growth is wanted, such as fence rows, ditch banks, driveways, roadsides, parking lots, and recreation areas. 

Herbicide selectivity may vary according to the application rate. High rates of selective herbicides usually will injure all plants at the application site. Some nonselective herbicides can be used selectively by applying them at a lower rate. Other factors that affect selectivity include the time and method of application, environmental conditions, and the stage of plant growth. 

Products are formulated as tablets and powder to kill larvae in livestock confinement areas and cockroaches in residences. Solutions are rarely sprayed as a nonselective herbicide. 

Formnlated as powders and solutions and often mixed with other herbicides they are spread or sprayed as nonselective herbicides. 

The increasing use of nonselective herbicide products on herbicide-tolerant crops accompanied by the concerns on the safety of adjacent nontolerant crops or noncropped environment. 

Amitrole is a nonselective herbicide, readily absorbed by the roots and leaves of the plant, and rapidly translocated in the xylem and phloem (Crafts and... 

Selective herbicides act like hormones, very selective biochemicals that control a particular chemical change in a particular type of organism at a particular stage in its development. Most selective herbicides in use today are growth hormones they cause cells to swell, so that leaves become too thick for chemicals to be transported through them and roots become too thick to absorb needed water and nutrients. Nonselective herbicides usually interfere with photosynthesis and thereby starve the plant to death. On application, the plant quickly loses its green color, withers, and dies. 

Selective herbicides Herbicides that kill only a particular group of plants Nonselective herbicides Herbicides that kill all plant life... 

Which is more likely to be a hormone, a selective or a nonselective herbicide ... 

Nonselective herbicides Herbicides that kill all plant life Nuclear reaction A process in which an isotope of one element is transformed into an isotope of another element Nucleic acids Biomolecules that control heredity (DNA, RNA) polymers of nucleotides that contain deoxyribose or ribose, nitrogen bases, and phosphate groups Nucleons Protons and neutrons... 

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