HERBICIDES in Asian rice - IRRI books - International Rice ...

spectrum herbicides glufosinate-ammonium (Basta) and glyphosate (Roundup)
(DeGreef et al 1989, Della-Cioppa et al 1987). Most herbicide-resistant varieties have
been developed and patented in industrialized countries, although the number of agricultural
field trials of transgenic plants being screened for herbicide resistance has
been steadily increasing in less developed countries. It is likely that biotechnology
will be used to develop other traits for weed control in rice as well, such as allelopathic
activity and anaerobic tolerance, and to increase the effectiveness of plant pathogens
for biological control of rice weeds (Toenniessen 1996).
POLICY IMPLICATIONS
The wide array of cultural, biological, and technological options that now exists for
weed control in rice makes the design of an IWM strategy increasingly complex.
Three sets of decision processes must be evaluated in determining the appropriate
role of herbicides in such a strategy:
• Farm-level weed management decisions that focus on input costs and crop
productivity.
• Regulatory decisions by a government that focus on the social costs of weed
control practices, including potential labor displacement, health damages, and
environmental effects.
• Strategic research program decisions by international and national agricultural
programs that focus on the use of varietal improvement and biotechnology.
Development of an overarching strategy for managing herbicides in Asian rice
systems is further complicated by the fact that decisions by farmers, governments,
and national agricultural research systems differ widely among countries. For example,
weed management choices in Japan, where wages are high and agricultural
research and development well established, may be very different from those in Cambodia
and Myanmar, where wages are low and agricultural research and development
more limited. Similarly, the strict regulatory environment for herbicide registration
and use in the United States cannot be expected to be transferred directly to Japan, let
alone to less developed countries like Bangladesh (Shibayama 1996, Hill 1996).
Moreover, current research on herbicide use in Asian rice systems remains focused
primarily on cultural and technological options for weed management. What
appears to be lacking is a focus on institutions. A strong commitment by the governments
of Asian countries is needed to ensure that herbicides are used safely and in
combination with other weed control practices, in order to minimize labor displacement
and environmental and health-related risks. Although herbicides are being marketed
aggressively by private chemical companies in many rice-producing areas, their
use has not been incorporated consistently into extension recommendations (Ho 1996).
As a result, the misuse of herbicides is common, posing health and environmental
risks that might not otherwise exist. A combination approach to weed control which
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