WEED ECOLOGY IN NATURAL AND AGRICULTURAL SYSTEMS by B.D. Booth, University of Guelph, Canada, S. D. Murphy, University of Waterloo, Canada and C. J. Swanton, University of Guelph, Canada. This textbook introduces ecological principles to students interested in weed science and weed management. ECOLOGY OF WEEDS AND INVASIVE PLANTS, 3rd Edition The newly revised and updated classic reference, Ecology of Weeds and Invasive Plants: Relationship to Agriculture and Natural Resource Management, 3rd Edition, by S.R. Radosevich, J.S. Holt, and C.M. Ghersa, is available for purchase from John Wiley. HERBICIDE PHYSIOLOGY: PSPP 546 An online graduate course offered through the Department of Plant Sciences & Plant Pathology, Montana State University. WEEDOMETER An online tool used to estimate germination and flowering at various locations within the United States.