ABSTRACT
The concept of systemic control of weeds through absorption by roots and top growth of the plant and translocation in the plant body and the use of organic chemicals for weed control took root wi th the introduction of nitrophenols as selective herbicides in 1935. The discovery of 2,4-D in the early 1940s, however, revolutionized the chemical method of weed control. It was in 1941 that Pokorny reported synthesis of 2,4-D which, interestingly, was first tried and found ineffective as a fungicide and insecticide. In 1942, Zimmerman and Hitchcock tested 2,4-D as a growth regulator. The credit for introducing it as a herbicide goes to Marth and Mitchell of the USA, who in 1944 reported selective weed control by 2,4-D in a bluegrass lawn and Hammer and Tukey, also of the USA, who in the same year used 2,4-D successfully in field weed control. Thus, demonstration of the herbicidal properties of 2,4-D in field weed control represented a technological breakthrough that heralded the modern era of weed management.
