Comparison of herbicidal activity with

Soybean Herbicide tolerant 27.8 million pounds less herbicide active ingredients in 2001 (50.016 million acres) Comparison of glyphosate use with a theoretical alternative herbicide mix for each US state based on experts views... 

Cotton Herbicide tolerant 6.2 million pounds less herbicide active ingredients in 2000 (15.402 million acres) Comparison of herbicide use per acre in 2000 with herbicide use in same US state in year preceding introduction of herbicide tolerant cotton... 

Schop RN, Hardy MH, Goldberg MT (1990) Comparison of the activity of topically applied pesticides and the herbicide 2,4-D in short term in vivo assays of the genotoxicity in the mouse. Fundam Appl Toxicol 15 666-675 Selden R, Sasahara AA (1967) Central nervous system toxicity induced by lidocaine. Report of a case in a patient with liver disease. JAMA 202 908-909... 

The tetrahydroquinolylimidazolinone 4 (AC 263,754) was also found to be an active herbicide. It was anticipated that fusion of a heterocycle such as a pyran to pyridylimidazolinone 1 might also afford interesting herbicidal activity. With this background in mind, investigations directed toward the synthesis of isomeric pyranopyridine analogs were undertaken. This paper will focus on the synthesis and herbicidal activity of imidazolinyldihydropyrano[2,3-b]pyridinecarboxylic acid 5 and its derivatives. However, for comparison of the herbicidal activity, the other pyranopyridylimidazolinones such as 6, 7, and 8 will also be included. The syntheses of these compounds (i.e. 6, 7, and 8) have been reported elsewhere (8). 

The compounds described were tested in the greenhouse pre- and postemergence on various weeds and crops. We found that these pyranopyridylimidazolinones showed herbicidal activity with soybean selectivity comparable to 3, the commercial product imazaquin. Because of the soybean selectivity, the comparison of the herbicidal activity is focused on the control of common weeds found in soybeans. These weeds are crabgrass, foxtail, johnsongrass, cocklebur, morningglory and velvetleaf. The data is summarized in Table I. 

Canola Herbicide tolerant 0.531 million pounds less of active ingredient per year (0.871 million acres) Comparison of estimated glyphosate use per acre with that of theoretical alternative mixes of three herbicides... 

Although the synthesis program did not result in any commercial herbicides, two types of pyridazines were discovered which produced unexpected results, both in the level and the type of activity. The first series, which includes the 3-methoxy- and the 3-dimethylaminopyridazines, resulted in a high level of postemergence activity not observed in the lead or in the other 3-sub-stituted-pyridazines. Secondly, based on a comparison with the N-oxides of other pyridazines, the N-oxide of the 3-hydropyridazine resulted in unexpectedly high preemergence activity, yet without phytotoxicity to cotton. 

In comparison with the unsubstituted compound (Ri = R2 = H), it was, consequently, revealed that the introduction of substituents into 4 and 6 positions of the pyrimidine was favorable for improving rice safety without decreasing herbicidal activity. In particular, the 4,6-dimethoxy compound, being a bis-pyrimidinyl compound, showed both a remarkable improvement in rice safety and excellent activity against Echinochloa spp. and broad-leave weeds. Finally, the sodium salt of 2,6-bis[(4,6-dimethoxypyrimidin-2-yl)oxy]benzoic acid (14, bispyribac-sodium) was selected to be commercialized as a herbicide on direct-seeded rice [22]. 

Herbicidal Activity. Table I summarizes herbicide data for two representative o-butyrolactone sulfonylureas of formula 4 and provides a comparison with their open-chain counterparts. These data were obtained from greenhouse tests in both pre-and postemergence applications on a variety of weeds and crops. For the sake of clarity, results are presented only for three or four grass weeds, three broadleaf weeds and wheat. The numbers reported in Table I represent percent injury of the particular plant species tested relative to an untreated check (0% injury). 

Comparison of the preemergence data at 0.25 kg/Ha for 2 (imazapyr), 3 (imazaquin), 4 (AC 263,754) and 5 reveals that the pyrano[2,3-b]pyridylimidazolinone 5 had excellent control of weeds with complete safety on soybeans at this rate. Its soybean safety was even better than that of 3, although its control of weeds was not as effective. However, at the rate of 0.50 kg/Ha this compound showed 95% control of the weeds while retaining complete safety on soybeans. The tetrahydroquinolyl-imidazolinone, 4, also had excellent herbicidal activity but caused more injury to soybeans. Similar results were observed for these compounds in the postemergence tests, but the selectivity in soybeans was lower in all cases than in the preemergence screens. 

Figure 4 shows the synthesis of 15 in which the phenyl group in the chloro carboxamide series was replaced with a t-butyl group. Compound 15 was herbicidal at 1 Ib/acre in the greenhouse. A comparison of the herbicidal activity of compounds 5, 11 and 15 showed that 11 was two times as active as 15, and four times as active as 5 (data not shown). It was determined that the analogue that best fit the structural requirements for herbicidal activity was the 5-cyano-l-(1,1-dimethylethyl)-N-methyl-lIi-pyrazole-4-carboxamide 1. However, in contrast to the phenyl series the chlorine atom of 13 was inert towards displacement by cyanide ion under a variety of conditions, apparently due to a combination of steric and electronic effects. 

Comparison of Acetyl-CoA-Carboxylase (ACC) Inhibitors with Acetolactate Synthase (ALS) Inhibitors The response patterns from four chemically-unrelated herbicides are compared in Figure 4 The structural formulas of the compounds are given in Figure 6 These treatments have been carried out with different amounts of the active ingredients Therefore, one should not look at the bars too quantitatively the increase or decrease of metabolites is what is important ... 

Recent general spectral studies of such nitriles include the vibration spectra of 2-pyrazinecarbonitrile and a (> 99%)15N-isotopic version 1172 the mass spectra of 2,3-pyrazinedicarbonitrile, its 5,6-diphenyl derivative, and 2,3,5,6-pyrazinetetracarboni-trile for comparison with those of analogous heterocyclic nitriles 1406 and the 15C NMR spectra of 2-pyrazinecarbonitrile and the like for correlation with their reactivities toward acetone enolate anions.251 The structure-activity relationship of pyrazinecarbonitriles as herbicides has been reported.1048... 

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