ABSTRACT
Since the first organic herbicides were developed for weed control in the late 1940s and early 1950s, we have seen the emergence of a vast arsenal of ever more specific and more active organic herbicides. Starting with the auxinic phenoxy acids and then sequentially adding photosynthesis-inhibiting phenylurea and s-triazine compounds, the bleacher amitrole, and an ever growing number of new structures, about 400-500 organic herbicide compounds are known to have been commercialized. These are divided into ca. 70 chemical structure groups. Of these, however, only 272 are presently registered (1). In this chapter, 148 herbicidal compounds acting at 23 different primary (molecular) targets are presented, including some new targets that have not yet led to commercial products (Table 1). This selection may be compared to the classification of herbicides according to their modes of action and to the structures that the Herbicide Resistance Action Committee (HRAC) has presented at its Internet site (2). Common and chemical names and further details on the chemical and physical properties of herbicides and pesticides in general may be found in ‘‘The Pesticide Manual’’ (3). A compilation of the scientific and common names of all main weed and crop plants known worldwide together with approved five-letter computer codes is available (4). The herbicide modes of action have been summarized in several sources (5-11).
