Herbal Herbicides
Weed killers manufactured by Mother Nature
By Janet Raloff
Certain plants are picky about the company they keep. Once established, walnuts and some sandy shrubs, for instance, create a virtually barren border of ground around them. Many other plants aren’t quite so antisocial. They permit numerous species into their neighborhoods, while barring a few plant types.
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Chemical defenses play a major role in determining which plants flourish in woodlands, meadows, farms—or even in suburban lawns. Although this herbal warfare has been recognized since Biblical times, its study is “still regarded as a relatively young and immature field of science,” notes Yoshiharu Fujii of Japan’s National Institute for Agro-Environmental Sciences in Tsukuba.