International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
Prevention and Management of Herbicide-Resistant Weeds in Rice
Experiences from Central America with Echinochloa colona
Bernal E. Valverde, Charles R. Riches, and John C. Caseley.

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You can download the full book in PDF format for free All that is asked is that you read the information provided by the authors (below), then fill out some information about yourself that will be e-mailed directly to the senior author (Bernal Valverde).  NOTE: ENGLISH AND SPANISH VERSIONS

Rice farmers in many parts of the world, particularly those establishing the crop by direct seeding in Latin America and USA, rely heavily on herbicides. With the repeated and intensive use of products with the same mode of action, resistance to a wide array of useful herbicides has appeared in many key weed species of rice. The introduction and almost universal adoption of propanil, from the early 1960s provided growers with a relatively inexpensive and reliable tool for controlling Echinochloa species and a number of other important weeds. Following the regular use of this herbicide for 10-15 years, farmers experienced the evolution of propanil-resistant populations of E. colona in many areas of Central America, Colombia, Mexico and Venezuela, and of resistant populations of E. crus-galli in USA. We estimate that 80% of the rice producing area of Central America is infested with E. colona and about 75% of farms have propanil-resistant populations. In addition, fenoxaprop-resistant populations of the weed have also been found where this has been used for as little as four seasons in an attempt to control propanil-resistant E. colona.

The Crop Protection Programme of the UK Department for International Development, ( has funded collaborative research on herbicide-resistant rice weeds involving the Tropical Agriculture Centre for Research and Higher Education (CATIE, Costa Rica,, the Natural Resources Institute, University of Greenwich, UK ( and the Institute of Arable Crops Research Long Ashton Research Station, UK ( The research team has described the extent of the propanil-resistance problem in Central America, determined the mechanism of resistance, developed and validated integrated weed management strategies for the prevention and control of resistant E. colona.

A summary of this research has been published in book form, a copy of which is available here. Single copies may be downloaded on the understanding that these are intended for educational use or private study only and not for commercial reproduction. The copyright to this electronic copy is retained by the authors whose permission must be sought before any of the material is used in a different form. We thank the DFID Crop Protection Programme for generously funding the preparation of the book. DFID, however, can accept no responsibility for any information of views expressed.

We hope that our work will contribute to a greater awareness of the problem of herbicide resistance and opportunities for resistance management in rice.

For further information, contact the authors:

Bernal E. Valverde
The Royal Veterinary & Agricultural University
Weed Science 
Agrovej 10
DK-2630 Taastrup
E-mail: or

Charles R. Riches
Natural Resources Institute
Long Ashton Research Station
Bristol BS41 9AF
United Kingdom

John C. Caseley
Long Ashton Research Station
Bristol BS41 9AF
United Kingdom
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Wednesday, July 24, 2024 .  Available
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