Abstract

That growth-regulating substances have found wide use in the field of agriculture as weedkillers in recent years, revolutionising the method of eradication of weeds is too well known to need emphasis. Among the synthetic hormones, derivatives of phenoxyacetic acid such as 2, 4-D (2, 4-Dichloro-phenoxy acetic acid), MCPA (2-methyl 4-chloro phenoxyacetic acid) and 2,4,5-T (2,4,5-Trichloro phenoxy acetic acid) have proved to be the most effective. Commercial preparations of these are available in various forms such as acids, mineral salts, organic salts or amines and esters under different trade names. Against broad-leaved weeds 2, 4-D and MCPA are the most commonly used hormone weedicides. There is no great difference between these two chemicals in their biological activity. 2, 4, 5-T is also closely allied to 2, 4-D and has been found very effective in killing shrubby weeds and woody plants. It finds use also as an arboricide for killing trees and tree stumps.

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