HERBICIDES in Asian Rice: Transitions in Weed Management, Ed
Total Page：16
File Type：pdf, Size：1020Kb
DEDICATION To Keith Moody WEED SCIENTIST As an agronomist and leading weed scientist at two major centers in the CG Sys- tem—the International Rice Research Institute (IRRI) from 1975 to 1995 and the International Institute of Tropical Agriculture (IITA) from 1969 to 1975—Keith Moody has played a critical role in designing strategies for weed management as part of the Green Revolution for rice. He has worked with scientists in nearly all countries of Asia and West Africa where rice is grown, and he has published more than 200 re- search papers in internationally refereed journals. His professional memberships in- clude International Weed Science Society (president, 1984-88), Asian-Pacific Weed Science Society (treasurer, 1984-90), and Weed Science Society of the Philippines (president, 1984-85; vice-president 1983-84, member of the board of directors, 1976- 86 and 1988). His professional service includes Weed Abstracts (editorial advisory board member), Crop Protection (international editorial board member), and Journal of Plant Protection in the Tropics (panel of reviewers-members). He coordinated IRRI’s weed science training short course and guided more than 30 degree candidates and research fellows. Keith Moody has challenged weed scientists throughout Asia and Africa to pay close attention to farmers and their traditional methods of weed control. He has sought to develop an integrated weed management strategy for rice production that is scien- tifically sophisticated, compatible with traditional pest management practices, profit- able for farmers, and nondamaging to the environment. His knowledge of farmers’ behavior and field conditions with respect to weeds is unsurpassed. It is to his excite- ment for weed science and to his deep concern for the welfare of rice farmers and the health of rice-based ecosystems that this volume is dedicated. Herbicides in Asian rice: transitions in weed management EDITED BY ROSAMOND NAYLOR The International Rice Research Institute (IRRI) was established in 1960 by the Ford and Rockefeller Foundations with the help and approval of the Government of the Philippines. Today IRRl is one of 16 nonprofit international research centers supported by the Consultative Group on International Agricultural Research (CGIAR). The CGIAR is sponsored by the Food and Agriculture Organization of the United Nations, the International Bank for Reconstruction and Development (World Bank), and the United Nations Development Programme (UNDP). Its membership comprises donor coun- tries, international and regional organizations, and private foundations. As listed in its most recent Corporate Report, IRRl receives support, through the CGIAR, from a number of donors including UNDP, World Bank, European Union, Asian Development Bank, Rockefeller Foundation, and Ford Foundation, and the interna- tional aid agencies of the following governments: Australia, Belgium, Canada, People's Republic of China, Denmark, France, Germany, India, Indonesia, Islamic Republic of Iran, Japan, Republic of Korea, The Netherlands, Norway, Philippines, Spain, Sweden, Switzerland, United Kingdom, and United States. The responsibility for this publication rests with the lnternational Rice Research Institute. The designations employed in the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of IRRl concerning the legal status of any country, territory, city, or area, or of its authorities, or the delimitation of its frontiers or boundaries. Copyright International Rice Research Institute 1996 Los Baños, Philippines Mailing address: P.O. Box 933, Manila 1099, Philippines Phone: (63-2) 845-0563, 812-7686 Fax: (63-2) 891-1292, 845-0606 Home page: http://www.cgiar.org/irri Riceweb: http://www.riceweb.org Electronic mail: [email protected] Telex: (ITT) 40890 RICE PM (CWI) 14519 IRILB PS (RCA) 22456 IRI PH (CWI) 14861 IRI PS Suggested citation: Naylor R, ed. 1996. Herbicides in Asian rice: transitions in weed management. Palo Alto (California): Institute for International Studies, Stanford University and Manila (Philippines): International Rice Research Institute. 270 p. Editor: LaRue Pollard Copy editor: Teresita Rola Layout artists: Ariel Paelmo, Millet Magsino Illustrator: Doris Rifareal ISBN 971-22-0093-0 CONTENTS FOREWORD vii Effect of herbicide use Kenneth S. Fischer on soil microbiology 69 Deputy Director General, IRRl PA. Roger and I. Simpson PREFACE ix Impact of herbicide use Rosamond Naylor, llS on the environment 95 D.G. Crosby ACKNOWLEDGMENTS xii Effect of herbicide use OVERVIEW on aquaculture 109 K.M. Li and P.Z. Li Herbicide use in Asian rice production: perspectives from economics, ecology, Ecological forces influencing and the agricultural sciences 3 crop-weed competition 121 R. Naylor S.E. Weaver Weed community dynamics Ecological forces influencing in ricefields 27 weed competition and K. Moody herbicide resistance 129 K.U. Kim Herbicides in United States rice production: lessons for Asia 37 INTEGRATED WEED MANAGEMENT J.E. Hill and L.S. Hawkins Integrated weed management IMPACTS OF HERBICIDES in rice in Asia 145 S.K. De Datta and A.M. Baltazar Herbicides and rice farmer health: a Philippine study 55 Introducing integrated weed P.L. Pingali and C.B. Marquez management in Malaysia 167 N.K. Ho Bioherbicides and weed management USE OF HERBICIDES IN ASIAN RICE in Asian ricefields 183 E.J. Cother Economic and technological influences on herbicide use in the less developed Genetic improvement of rice countries of Asia 233 for weed management 201 K. Moody G.S. Khush Experience with rice herbicides Using biotechnology in genetic in Japan 243 improvement of rice for weed H. Shibayama management 209 G.H. Toenniessen Developing a weed management strategy for Asian rice production 255 Identifying allelopathy R. Naylor, W. Falcon, and D. Kennedy in rice germplasm 219 R.H. Dilday, W. Yan, and J. Lin Participants 267 vi Contents FOREWORD Weeds have been a persistent problem in rice since the beginning of settled agricul- ture. For Asia as a whole, weeds cause an estimated 10-15% reduction in rice yields- equivalent to about 50 million tons of rough rice annually. Traditionally, rice farmers have managed weeds primarily through water control and by hand labor. Now, rice farming is undergoing rapid change. Labor costs are increasing as labor supplies in the rural sector dwindle, and the availability of water for agriculture is decreasing. Farmers are turning to new rice culture techniques- direct seeding instead of transplanting and reduced use of water for early weed sup- pression. With these new ways of growing rice, weed control relies heavily on herbi- cides. The increasing use of herbicides, while lowering production costs, also poses risks to the environment and human health. Perhaps most worrisome for the future stability of rice agriculture is the potential buildup of herbicide resistance in weeds where herbicides are overused or used inappropriately. Research on weed ecology and management in Asian rice systems is at a water- shed. Ensuring the sustainability of rice production systems calls for much broader, more integrated weed management strategies. The challenge for IRRI and national rice research programs in Asia is to increase the cultural, chemical, and biological methods available for weed management; to expand knowledge and understanding of weed ecology; and to integrate knowledge, understanding, and new methodology into realistic weed management systems for farmers. This effort requires the cooperation of both private and public sectors, and the participation of policy makers, national and international research communities, and, of course, rice farmers themselves. Immediate attention needs to be directed to the benefits and risks of herbicide use and misuse in rice, without repeating the shortcomings of Asia’s 20-yr-old experience with insecticides. Two decades ago, the intensification of rice production to increase the food supply for an additional 600 million people in Asia pressured changes in rice insect pest populations. Over reliance on pesticides to control the new levels of harm- ful insects caused adverse responses in insect communities. These responses, charac- terized by repeated cases of pesticide resistance, generated new areas of research, which led to a better understanding of the rice-refuge-pest-predator relationships. That understanding makes it possible to manipulate and reestablish the natural resil- ience of rice ecosystems at higher levels of productivity. While most herbicides are much less toxic and persistent than the majority of the insecticides applied in Asian rice production, widespread use of herbicides in densely populated areas—especially when the chemicals are misused—is cause for concern. It is time for researchers and their farmer partners to undertake work to better under- stand the changing ecology of weed pests as a basis for developing tactics for envi- ronmentally sound weed management. New weed management is needed that allows farmers to profit from rice farming in our changing world. The question of how to manage rice herbicides appropriately in Asia was ad- dressed by a conference held at Stanford University in 1994. Scientists from several national research programs in Asia, science and policy researchers from academic institutions and private agrochemical industries, and scientists from IRRI presented discussion papers. The conference was an outstanding forum for these knowledge- able individuals to discuss