ABSTRACT
The intensive and continuous use of herbicides over the last five decades has resulted in the development and evolution of weeds resistant to the normally phytotoxic chemicals. Since the first reports of triazine resistance in the mid-1960s, over 150 weed species have been identified as having developed biotypes resistant to at least one or more herbicide classes. Resistance to at least 15 classes of herbicides have been noted [82,153]. Moreover, the area of land infested w i t h resistant weeds is increasing rapidly. Reports of evolution of newly resistant biotypes continue to emanate from all over the wor ld , including developing countries, e.g., India [90], where extensive use of herbicides in grain crops began only in the late 1970s. These reports indicate that herbicide resistance problems are accelerating and, consequently, management of weeds is becoming increasingly more difficult and complex.
