ABSTRACT
Chromolaena odorata is considered a noxious weed in many parts of the world (Olaoye 1986; Torres and Paller 1989; Waterhouse 1994). It is a major colonizer in slash-and-burn agriculture and is particularly widespread in Africa (de Rouw 1991) and Asia (Nakano 1978; Kushwaha et al. 1981). C. odorata was introduced to India in the 1840s (McFadyen 1989) and, by 1920, was regarded as a serious, rapidly spreading weed in Burma (Rao 1920). It reached Thailand in about 1924 and spread to Laos in the late 1920s (Chevalier 1949; Vidal 1960). Although it failed to rate a mention in a 1942 description of upland agricultural systems in Indochina by Gourou, which was based on observations made in the late 1930s (Gourou 1942), Izikowitz (1951) described the invasion of C. odorata into what is now Luang Namtha Province during the 1940s.
