Herbicides control

In order to estimate the analytical accuracy of the method with a given set of water samples, a certain number of control water samples should be fortified with a known amount of each herbicide. Control water samples are fortified at different analyte levels across the range of anticipated concentrations. For example, 0.010g of analyte is necessary for a 0.05 agL fortification of a 200-mL sample. This would be accomplished by adding 1.0 mL of a 0.010 o.gmL solution to the sample. The deuterated standards are not incorporated in the fortification solutions but may be added to all control and fortified samples for internal correction of recovery. The following solutions are used to fortify control water samples ... 

McCormick, C.L. and M.M. Fooladi, "Synthesis, Characterization, and Release Mechanisms of Polymers Containing Pendant Herbicides," Controlled Release Pesticides, ACS Symposium Series 53, 112-125, H.B. Scher, ed., Washington, D.C., 1977. 

This comprehensive definition makes it elear that a wide number of substances may be eonsidered to be pestieides, and that the eommonality among all pestieides is their ability to provide eontrol over pests. A variety of classifications for pesticides have been developed that are specific for the type of pest controlled. Insecticides, for example, are pesticides that control insects, while herbicides control weeds and fungicides control plant diseases (molds). In addition to these major classifications of pesticides, there are many other classifications. These include nematicides (for nematode control), acaracides (mite control), rodenticides (rodent control), molluscicide (snail and slug control), algacides (algal control), bacteriocides (bacterial control), and defoliants (leaf control). 

Herbicides control weeds and are the most widely used class of pesticides. The latest US EPA data show that some 578 million pounds of herbicides were used in the United States in 1997 and accounts for some 47% of pesticides used. This class of pesticide can be applied to crops using many strategies to eliminate or reduce weed populations. These include preplant incorporation, pre- and postemergent applications. New families of herbicides continue to be developed, and are applied at low doses, are relatively nonphytotoxic to beneficial plants and are environmentally friendly. Some of the newer families such as the imidazolinones inhibit the action of acetohydroxyacid synthase that produces branched-chain amino acids in plants. Because this enzyme is produced only in plants, these herbicides have low toxicities to mammals, fish, insects, and birds. 

Atrazine is the only proven product for control of these six common and economically important broadleaf weed species with ALS-resistant biotypes in com. Product labels for each of the ALS herbicides recommend tank mixtures with atrazine. When used in the corn-soybean rotation, atrazine use in com breaks the continuous use of ALS-inhibitor herbicides and delays the spread of ALS-resistant biotypes. For example, Owen el al., (1995) reported that none of the ALS herbicides controlled ALS-resistant common lambsquarters, but atrazine provided excellent control. Sprague et al. (1997c) reported excellent control with atrazine both preemergence and postemergence on ALS-resistant, cross-resistant, and susceptible biotypes of common waterhemp. 

Tierney, M.J. and R.E. Talbert (1995). Herbicidal controls for ALS-inhibitor resistant common cocklebur. Proceedings South Weed Science Society, p. 257. 

Farmers use cultivation and herbicides in their weed control programs because of their complementary nature in controlling weed species that are missed if exclusive reliance were to be placed on either technique alone. One way to decrease herbicide use with additional cultivation while controlling weeds in the corn row is to band the herbicide over the row of corn plants. Essentially, the herbicide controls the weeds within the row, while the weeds between the rows are effectively controlled with mechanical cultivation. 

Uses insecticide/fungicide/herbicide control of termites as wood preservatives to protect against fungal rots and wood boring insects as a pre-harvest defoliant in cotton and also as a general pre-emergence herbicide. 

Another example found in herbicides is the ALS inhibitor flucarbazone-sodium (Everest ) [87]. This postemergence wheat herbicide controls grass weeds, as well as a number of broadleaf weeds of commercial significance. 

Russell, W.E., The Growth and reproductive characteristics and herbicidal control of Jerusalem artichoke (Helianthus tuberosus), Ph.D. thesis, Ohio State Univ., Columbus, OH, 1979, 86 p. 

Another variation in herbicide control of volunteer Jerusalem artichokes in soybeans is through the use of roller, pipewick, or bobar wick applicators (Coultas and Wyse, 1981) with glyphosate or 2,4-D amine, the former being more effective. At least two applications approximately 2 weeks apart are recommended, and the weeds should be at least 15 cm taller than the soybeans before treatment. Variable results appear to be due to the lack of uniformity in height of the Jerusalem artichokes. At this time, selective application techniques have not proven to be sufficiently effective. 

Russell, W.E. and Stroube, E.W., Herbicidal control of Jerusalem artichoke, North Central Weed Control Conference, 34, 48 49, 1979. 

Broad spectrum Animals. Rapidly excreted by rat, goat, and herbicide controlling hen. Metabolism via cleavage of the molecule grasses followed by conjugation of flurophenyl... 

Herbicide Weeds, plants Total herbicide kills all plants Selective herbicide controls weeds... 

A computer survey of the patent literature made a year ago came up with 515 recent patents claiming herbicidal synergies. A perusal of the abstracts of 45 of them, chosen as a sample, showed that the patent community uses a broader definition of synergy than used here they believe that there is a synergism when two herbicides control more weed species than each separately. This would better be termed "complementarity. The overlap of control range allows a lowering of herbicidal rates, which may or may not be due to a metabolic... 

In 1982, American Cyanamid began commercial development of the imidazolinone class of herbicides. These herbicides control a broad spectrum of economically important weeds in corn and soybeans. Although differences in tolerance of corn hybrids for imidazolinone herbicides exist (5), no hybrids with sufficient tolerance to allow application of current imidazolinone herbicides to corn fields have yet been identified. Other methods to supplement the inadequate levels of natural tolerance have likewise been ineffective. 

Butisan . [BASF AG] Metazachlor systemic herbicide controlling annual grasses, broadleaf weeds. 

Meturon . [Griffin] Fluometurai herbicide controlling annual grasses and bioadleaf weeds in cotton and sugarcane. 

MAJOR USES Used for herbicide control on broadleaf plants, grasses, wheat, com, sugarcane, barley, oats, rice, lawns and turf, non-crop areas pasture and jungle defoliation plant growth regulator. 

OTHER COMMENTS used as a selective weed killer and defoliant used for herbicide control useful in forest management (e.g., bush control, tree injection, increases latex output of old rubber tress) basic material from which the soluble esters and salts are produced. 

Dose/response curves were developed from traces such as those shown in Figure 2 for dinoseb. For comparative purposes, the concentration of compound required to induce an increase in the swelling rate of 0,02 A in 1 min relative to the no-herbicide controls is shown in Table V for chloroplasts, thylakoids, and mitochondria, Thylakoids did not swell as extensively as the other two organelles, consequently, the values are for a change of 0,01 A, The relative order of activity shown by the compounds is similar to that given in Table IV for inhibition of valinomycin-induced swelling in the three organelles. 

Concentration (yM) required to induce an increase in the swelling rate of 0,02 A in 1 min, relative to the no-herbicide controls. 

Concentration (yM) required to induce efflux of K at a rate of 100 nmoles/mg chlorophyll 2 min above the no-herbicide control rate. 

Concentration (yM) required to increase the rate of ferri-cyanide reduction to 80 nmoles/min. The no-herbicide control rate was about 40 nmoles/min. c /... 

Dose/response curves were developed from traces such as shown in Figure 3B for dinoseb. For comparative purposes, the concentration of compound required to increase the rate of ferricyanide reduction to twice that of the no-herbicide control rate are shown in the last column of Table VI. Uncouplers such as FCCP accelerate the rate of ferricyanide reduction, presumably by shuttling protons across the membrane in response to the electrical potential generated by the reduction of ferricyanide by ferrocene (28). In this study, FCCP was the most effective compound. The two phenolic herbicides (dinoseb and ioxynil) were more active than propanil and chlorpropham. Among the carbanilates, 3-CHPC and... 

Dextran mixed with PVP and poly(vinyl acetate) was crosslinked with epichlorohydrin to fonn beads containing herbicides. Controlled release of herbicnles. Rehab et at., 1991... 

Remarkable selectivity of action has now been achieved in some cases, such as the herbicides controlling the pest wild oats in cereal crops, and insecticides like Menazon attacking aphids but not bees and ladybirds. The increasing attention to selectiveness in activity also promises to reduce problems of resistance and cross-resistance which have been encountered with broad-spectrum pesticides like DDT and the organophosphates. 

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