Chemical herbicides are without question the most effective immediate solution to most weed problems. They are not, however, the only option or necessarily the best for all weed control situations (23, 24, 34). Recent commercialization of two biological herbicides illustrates another weed control technology with potential (24, 27, 44, 50). Abbott Laboratories marketed the fungus Phytophthora palmivora Butler in 1981 for control of strangler vine (Morrenia odorata Lindl.) in Florida citrus groves. The Upjohn Company will market the fungus (Colletotrichum gloeosporioides f. sp. aeschynomene (c.g.a.) in 1982 for control of northern jointvetch [Aeschynomene virginica (L.) B.S.P.] in Arkansas rice (Oryza sativa L.) and soybean [Glycine max (L.) Merr.] fields (45).

Thomas Karp Pavlychenko's pioneering investigations on the root systems of crops and weeds and the results of his research on weed biology and ecology at the University of Saskatchewan in the 1930's and 1940's provided the foundation for many of the principles of modern weed science. His classical studies in which he quantified the distribution and length of roots of many plant species continue to be regarded as being of unsurpassed caliber. In addition to his work in the areas of crop ecology and plant competition, Pavlychenko is also noted for his many contributions relating to the cultural and chemical control of weeds. In this paper, a brief chronicle of Pavlychenko's life and major accomplishments during his remarkable career at the University of Saskatchewan and later with the American Chemical and Paint Company is presented.