Herbicide growth inhibitor

The inhibitors of amino acid synthesis, sulfonylureas, imidazolinones, and glyphosate, were first recognized as general growth inhibitors that prevent mitotic entry (188,189). Whatever the mode of action, herbicides that inhibit amino acid synthesis also cause a rapid inhibition of cell growth, usually through inhibition of mitotic entry. 

Chlorthal-methyl. 2,3,5,6-Tetrachloro-l,4-benzenedicarboxylic acid dimethyl ester [1861-32-1] (chlorthal-methyl) (48) belongs to the class of chlorinated benzene compounds. It has very limited use on an experimental basis as an axillary shoot growth inhibitor in tobacco. Like many sucker control agents the compound is probably a contact one with its mode of action being most probably by plasmolysis. Each axillary shoot must be contacted and wetted by the spray solution in order to be killed (23). The compound, an old one, was originally called Dacthal, Rid, and DCPA. It was first developed and patented as a pre-emeigence herbicide (60). 

This method can be used to compensate for inhibition of a biochemical pathway which results in a deficiency of an essential metabolic product. Detailed variations of the method are provided by Dayan et al.7 and Amagasa et al.1 The inhibitor concentration should be no higher than that required for strong herbicidal effect. Metabolite concentrations should be below that which is phytotoxic. For example, certain amino acids such at methionine, are growth inhibitors at relatively low concentrations. So, in preliminary work, dose-response studies should be done with amino acids to find the maximum concentrations that do not inhibit growth. Then, seeds of test plants should be imbibed in solutions of the phytotoxin with and without metabolite solutions. Amino acids, tricarboxylic acid cycle intermediates, vitamins, nucleotides, and reducing agents have all been used in complementation studies to elucidate modes of action of a variety of phytotoxins. Examples of each of these is provided by Dayan et al.7... 

In considering whether MFO-catalyzed metabolism of herbicides is associated with cross-resistance in Lolium rigidum we have taken, initially, an indirect approach. Growth experiments with wheat showed that the MFO inhibitors aminobenzotriazole (ABT) and PBO synergized chlortoluron when the herbicide and inhibitors were added as a soil drench (34). This synergism was presumed to be due to the inhibition of MFO-catalysed metabolism of chlortoluron (27-29). Significantly, Kemp and Caseley (2) have shown that cross-resistant Alopecurus are relatively more susceptible to chlortoluron in the presence of ABT and other... 

Most commonly, growth is considered an irreversible increase in size, A more useful definition for discussing growth inhibitor herbicides would be "a combination of cell division and cell enlargement which leads to an irreversible increase in size". An inhibition of either one of these processes will result in an eventual inhibition of growth. 

Figure 1. Scheme for categorizing the mode of action of growth inhibitor herbicides. 

Herbicides and plant growth inhibitor The example compound is claimed to have exhibited complete control of Echinochloa crus-galli. 

The alkanolamines are used as neutralizers for acidic herbicides in agricultural applications. Their use in herbicide formulations also increases water solubility, reduces volatility, and improves the compatibility of other formulation components. The alkanolamines are intermediates in the preparation of growth inhibitors, herbicides, algaeicides, and fungicides. 

Cell Division Inhibitors. The most common mode of action of soil-appHed herbicides is growth inhibition, primarily through dkect or indkect interference with cell division (163). Such growth inhibitory activity is the basis for most pre- or post-emergent herbicides intended to control germinating weed seeds. In germinating seeds, cell division occurs in the meristems of the root and the shoot. Meristematic cells go through a cycle... 

Other auxin-like herbicides (2,48) include the chlorobenzoic acids, eg, dicamba and chloramben, and miscellaneous compounds such as picloram, a substituted picolinic acid, and naptalam (see Table 1). Naptalam is not halogenated and is reported to function as an antiauxin, competitively blocking lAA action (199). TIBA is an antiauxin used in receptor site and other plant growth studies at the molecular level (201). Diclofop-methyl and diclofop are also potent, rapid inhibitors of auxin-stimulated response in monocots (93,94). Diclofop is reported to act as a proton ionophore, dissipating cell membrane potential and perturbing membrane functions. 

Arsonic and arsinic acids have found a number of industrial uses. They have been used as corrosion inhibitors for iron and steel, additives to motor fuel, agricultural bactericides, herbicides, and fungicides. 3-Nitro-4-hydroxyphenylarsonic acid (roxarsone) [121 -19-7] C H AsNOg, has found widespread use as an additive to poultry feed for the control of coccidiosis and other poultry diseases (122,123). Arsanilic acid [98-50-0] C HgAsNO, has also been used for this purpose (124) and for growth promotion in swine. It is manufactured and suppHed by Duphar Nutrition Co., Inc., Fleming Laboratories, Inc., Dr. Mayfield Laboratories, Inc., and Whitmoyer Laboratories, Inc. 4-Nitrophenylarsonic acid [98-72-6] C H AsNO and... 

Nonmedical uses claimed for pyridopyrimidines include uses as growth promoters, cytokinins, herbicides, agricultural fungicides, coccidiostats, dyestuffs intermediates, UV absorbants and corrosion inhibitors. 

Results presented in Table VII show that sufficient light is needed for new shoot formation on explants and that the herbicide fluridone causes chlorosis in new growth just as in whole plants (12,13). These data also confirm that the apical explant, which contains the terminal meristem, is a poor system for assaying inhibitors of new shoot production. 

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