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

ECONOMIC AND TECHNOLOGICAL INFLUENCES
ON HERBICIDE USE IN THE LESS DEVELOPED
COUNTRIES OF ASIA
K. Moody
Production and consumption of rice are closely associated with the nations of South,
Southeast, and East Asia. In 1991, 520 million tons of rice were produced on 148
million hectares (IRRI 1993). Current production, however, cannot be sustained, much
less increased to the level needed within the next 25 yr, without greatly increasing the
productivity of current cropland (Barbier 1989).
Improved weed control will be an essential component of the technology needed
to achieve that objective (Williams 1992). Herbicides are currently the most widely
used method to control weeds. This agrochemical can be expected to be a major growth
area in the pesticide industry of less developed countries for at least the next decade.
For example, the rice herbicide market in China and India could increase from a total
of US$67 million to more than $550 million (Woodburn 1993). Over the next 6-8 yr,
average global expenditure on rice herbicides could exceed US$10 ha -1 , compared
with the current US$7.50 ha -1 .
In the Philippines, sales of pesticides during the 5 yr 1985-89 grew an average
19.8% for herbicides, 13.8% for insecticides, and 2.9% for fungicides. Most of the
herbicide (85%) was applied to rice, with more than 1 million ha treated nationwide
(Cruz 1990). Herbicide use on rice increased from 54% of all herbicide sales in 1981
to 82% in 1987 (Rola and Pingali 1993).
In India, herbicide use during the 1980s dramatically outstripped use of other
pesticides. Herbicides were only 2% of total pesticide use in the 1970s; they now
account for 12% of the herbicide market. About 2,000 t of herbicides are used annually
on more than 4 million ha of rice (Mehta 1992). In the Punjab area alone, herbicide
use in transplanted rice increased almost 600%, and 90% of the ricelands are
now treated with herbicides (Brar and Randhawa 1992). Herbicide use also is increasing
in less favorable rice-growing areas.
In Thailand, the rice herbicide market has increased dramatically. Products such
as bensulfuron-methyl, pretilachlor, and fenoxaprop-ethyl have benefited; older her-