Historically, many herbicides have been tested for control of purple and yellow nutsedge, (Cyperus rotundus L. # CYPRO and (C. esculentus L. # CYPES). However, most chemicals provide only poor or temporary control. Reasons for failure include marginal translocation of herbicides to sites of action, temporary inhibition of tuber sprouting, and control of new tuber formation or inconsistent control when applied at different stages of growth and under various environmental conditions. Evaluation criteria that emphasize control of new plants and foliage rather than inhibition of tuber sprouting or new tuber production also contribute to erratic results. Progress toward solving these research problems is evident in studies of the influence of herbicides relative to nutsedge growth stages, new tuber development, and tuber recovery following treatment. In this review, nutsedge response to herbicides grouped by their mode of action within plants will be summarized.

Extension workers often identify production, marketing, managerial, or educational constraints that reduce agricultural efficiencies. The preceding papers documented that both yellow and purple nutsedge (Cyperus esculentus L. # CYPES and C. rotundus L. # CYPRO) are serious weeds in many worldwide agricultural cropping systems. Detailed literature reviews and suggested directions for future research also were presented. As a partial summary of the symposium, this paper attempts to condense the information regarding yellow nutsedge into several options or strategies for consideration by year-round weed management practitioners.

Dr. James D. (Jim) Riggleman of Wilmington, DE, is Manager of Licensing for Du Pont's Agricultural Products Dep. He is responsible for identifying new herbicides, insecticides, fungicides, growth regulators and life science materials for Du Pont's development and marketing. Prior to this assignment, he was Manager, New Products Development.

Dr. Mercado is Professor, Department of Agronomy, University of the Philippines at Los Baños. Her undergraduate and Master's degrees are from the University of the Phillippines, and her Ph.D. from the University of Iowa. She has been active in weed science since the early 1970's and has trained some 27 M.S. and 8 Ph.D. students. In addition, she and her husband have raised a family of five children. Mercado is a well-recognized weed scientist in her part of the world, having lectured in Indonesia, Thailand, Korea, and Japan. Her weed science textbook, “Introduction to Weed Science,” is widely used in Asian countries. Among her many honors, perhaps those most prized would be three awards for outstanding achievement from her own University of the Philippines.

Johnsongrass [Sorghum halepense (L.) Pers. # SORHA], native to the Mediterranean region, is one of the worst weeds ever introduced into the United States. While the precise date of its introduction is unknown, johnsongrass probably was present early in the 19th century. Before 1874, johnsongrass, described under eight botanical names and identified by over 40 common names in the literature, was most commonly called guinea grass and Means grass.

Chlorimuron-ethyl is a highly effective postemergence herbicide for control of economically important broadleaf weeds in soybean. It has been developed by E. I. du Pont de Nemours & Co., Wilmington, DE, under the code DPX-F6025 and is marketed in the United States under the trade name of Classic. Chlorimuron-ethyl is a member of a new class of herbicides called sulfonylureas. It is active at extremely low use rates, and soybeans have good tolerance.