Chemistry of the Pesticides

Description

The advancing centuries brought about gradual but fundamental changes in man’s mode of living. From a predatory animal he became a cultivator of crops; later he banded together with his fellows to form small communities and villages. As his mode of life changed, man’s relationships toward insects and diseases assumed a more important place in his life. His first cultivated plants were native species which supplied him with food, clothing, or some other daily need. Cultivation at first consisted of clearing away the competitive vegetation and freeing the chosen plants from the natural competition to which they had previously been subjected. When such encouragement was given the selected plants, other difficulties appeared. The plants, now grown larger and probably more fruitful than in their original environment, became more at- tractive to man, and to insects and diseases as well. This occurred not only because of the increased size and vigor of the plant, but mainly because the natural vegetation, which had formerly grown in close proximity to the cultivated plants, was now removed.