Herbicide-resistant weed species have become widespread in recent years. Fifty-five weed species, including 40 dicots and 15 grasses, are known to have biotypes resistant to the triazine herbicides. One or more resistant species have arisen in 31 states of the United States, four provinces of Canada, 18 countries in Europe, and Israel, Japan, Australia, and New Zealand. Resistance to other classes of herbicides is more restricted in distribution and recent in detection but is becoming more widespread. Trifluralin resistance has spread in the southeastern United States and has been detected in Canada, while 11 species with biotypes resistant to paraquat have been reported around the world. Diclofop-methyl-resistant weed species are problems in cereal production in Australia and have been found in Oregon, South Africa, and the United Kingdom. Resistance to the substituted ureas also is present in the United Kingdom, West Germany, and Hungary. Within the last 2 yr, biotypes of at least four weed species resistant to the sulfonylurea herbicides have arisen following several annual applications of these herbicides in wheat. Some resistant biotypes have multiple resistance to different classes of herbicides, which greatly exacerbates the threat of resistance. Herbicide resistance has reached the level where more concerted efforts are needed in research, education, and development of effective management strategies to preserve herbicides as essential tools of agricultural technology.

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This book focuses on the recent progress made in understanding the genetic and evolutionary mechanisms underlying herbicide resistance in weeds. Current controversies on key aspects of resistance evolution are discussed. The authors of Herbicide Resistance in Weeds and Crops highlight crucial present and future research directions and challenges connected with understanding of weed resistance development and the importance and impact of herbicide-resistant crops.The information provided in this book serves as a beneficial device to illustrate current herbicide resistance research touching agriculture and environment, as well. Herbicide Resistance in Weeds and Crops should be principally valuable for scientists and researchers interested in advancing research strategies concentrated on accepting weed resistance as a global problem and proactive, evolutionary-based weed management options for agriculture today. I hope that this book will provide the scientific community with a source of crucial research knowledge to assist format prospective research and understanding weed and crop herbicide resistance.

Transformation of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-methylethyl)-acetamide] was studied with an actinomycete strain isolated from metolachlor-contaminated soil. Eight metabolites were obtained and identified by mass and NMR spectral analysis. Benzylic hydroxylation of the aralkyl side chains and/or demethylation a t the N-alkyl substituent appeared to be the only transformations involved. All metabolites had a monochlorine isotopic pattern, indicating that no dehalogenation of the chloroacetyl moiety occurred.

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