Postemergent herbicidal activity

Postemergence herbicidal activity has been shown by certain benzodiazepines (76MI1). 

These nicotinic acid intermediates were also converted to their corresponding ethyl esters by reaction with ethyl alcohol in the presence of sulfuric acid. Surprisingly, the alkyl amides had some pre- and postemergent herbicidal activity with bleaching symptomology. The activity was quite weak, less than 50% weed control was observed at 2 lb/acre. The esters, on the other hand, were almost devoid of herbicidal activity. 

Dialkyl- and 2,5,7-trialkylpyrimido[4,5-postemergence herbicidal activity against grassy and broad-leaved plant species.117 2-(5-Nitro-2-furyl)pyrimido[4,5-<7]pyrirnidin-4-amines possess antibacterial activities,118 and some pyri-mido[4,5-ef]pyrimidines exhibit a remarkable diuretic activity.11,119,120 Pyrimido[4,5-t/]-pyrimidine-4-thiol was found to be a weak inhibitor of L. casei.106... 

Biocidal 2-aryl-l,3-diones and their enol esters showing acaricidal and pre-and postemergence herbicidal activity were reported since the mid-1970 s as exemplified by 3-hydroxy-2-arylindones from Union Carbide [1], 3-Aryl-pyrrolidine-... 

Table 2. Postemergence Herbicidal activity at 16 g/Ha of Isomeric Pyrazole Esters.

On the basis of the preliminary bioassay, post-emergence herbicidal activity of most IG was further examined at 150 g ai/ha in the greenhouse. The results of postemergence herbicidal activity against rape, chingma abutilon, common amaranth, and white echpta are hsted in Table 2.41. 

Cyclic phosphonates IVE-7, IVE-9, and IVE-11 stiU exhibited significant postemergence herbicidal activity (70-100 %) against tested broad-leaved weeds even at 18.5 g ai/ha. Especially, IVE-9 with 2-Cl,4-F as Y displayed the best inhibition against all tested broad-leaved weeds, which could be comparable to clacyfos (IC-22, HW02), and exhibited better herbicidal activity against tested broad-leaved weeds than that of 2,4-D and glyphosate at 18.5 g ai/ha. 

Further bioassays were carried out in the greenhouse to confirm the postemergence herbicidal activity of IVF. AU of the compoimds IVF were applied at 150 g ai/ha to evaluate their post-emergence herbicidal activity against chingma abutilon, leaf mustard, common amaranth, and white eclipta. The results are listed in Table 5.23. 

In order to make sure the weed spectrum of cyclic phosphonates IVC-IVE, seven cyclic phosphonates were chosen to test at 150 and 75 g ai/ha for postemergence herbicidal activity against twenty-one species of dicotyledonous plants including fourteen species of weeds and seven species of crops. 

Bioassay for clacyfos was carried out in the greenhouse for its pre- and postemergence herbicidal activity, selectivity, crop safety and biological property at National Pesticide Discovery South Center (Zhejiang) or National Pesticide Engineering Research Center (Nankai University, Tianjin) in Chain. The results are summarized as follows. 

The preemergence and postemergence herbicidal activities of compounds were evaluated at different dosages in a set of greenhouse experiments. 

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