Postemergent activity

A variety of herbicides have been used in combination with simazine and other triazines. These herbicides have preemergence and postemergence activity and are primarily effective on grass and perennial weeds. The preemergence herbicides used in combinations with simazine include oryzalin, pendimethalin, prodiamine, norflurazon, oxy-fluorfen, and diuron. Glyphosate, oxyfluorfen, paraquat, and amino triazole (used in some parts of the world) are... 

DSMA is an organic arsenical having contact, postemergence activity. It was first utilized for crab-grass control in turf. It is an effective herbicide in cotton and in citrus trees, but must be used as a directed spray to avoid contact with the crop foliage. 

Platinum complexes, 161 Polarographic studies, 153, 154 of 2-aminothiazoles, 29 of 2-anilinothiazoles, 30 of 2-azothiazoles, 107, 108 Polyacrylonitrile, 105, 163, 164, 167 Polyamines, 156-168 Polycaprolactam, 156-168 Polyesters, 163, 165, 166, 167 Polyhalogenothiazole. reactivity of, 408-409 Polymers, e-caprolactam, butadiene, 438 Polymorphism, of sulfathiazole, 116 Positive colored image, 440 Postemergence activity, 134 Potassium salts, of acetamido thiazoles, 90 Potentiometric measurements, and amido-imido equilibrium, 116 and amino-imino equilibrium, 21 P.P.P. approximation, charge diagrams calculations by, 17... 

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 the case of analogous dialkyl derivatives, the postemergence activity of the 4-methyl derivative is stronger than that of the 4-trifluoromethyl derivative, while the opposite is true of their preemergence activity. 

Iwataki and Hirono (1978) found that the substituents of the cyclohexane ring and of the side-chain strongly influence herbicidal activity and selectivity. The cyclohexane ring is responsible for the postemergence activity of the molecule, the Rj-Rg alkyl substituents for its selectivity. 

TABLE 1. Postemergence Activity at 16 g/Ha of Harmony and Various Isomers. 

The heterocyclic analogs of EL-107 showed interesting herbicidal activity as preplant incorporated (PPI) and surface applied (SA) materials (Table). At high rates (8 Ib/acre) they showed postemergence activity. When preplant incorporated and surface applied, these compounds were best described as broadleaf herbicides most effective on redroot pigweed, jimsonweed, nightshade, and mustard. Some degree of foxtail millet control was seen at 0.5 to 1.0 Ib/acre. Crop safety was seen on the cereals and corn. 

Replacement of one or more of the thiophene rings of a-T by phenyl, pyridine, pyridiniun pyrimidine, triazine led to noticeable decrease in postemergence activity. 

The herbicidal activity and corp selectivity of IG-21 (code number for development HWS) were further examined at 1,200-50 g ai/ha. IG-21 was tested for postemergence activity against a range of plant species including purslane (Portulaca oleracea), slender amaranth (Amaranthus ascendens), goosefoot (Chenopodium album), spiny amaranth Amaranthus spinosus), sugarbeet Beta vulgaris), maize Zea mays) and rice Oryza sativa). Results are shown in Table 2.50. 

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