A Cleaner, Greener Rice Industry
Tuesday, September 26, 2000
Scientists from the International Rice Research Institute have found a new way to control a major disease in rice without using any chemicals - by planting different types of rice alongside each other.
Rice production, described recently as the single
most important economic activity on the planet, stands poised at the dawn of
a new era. For those who know the industry, the trend has been clear for
many years, but only recently did the public learn just how far things have
Source: International Rice Research Insititute
In what the New York Times described as a "stunning success" and one of the
"largest agricultural experiments ever," scientists from the
Philippines-based International Rice Research Institute (IRRI) found a new
way to control a major disease in rice without using any chemicals.
By planting different types of rice alongside each other, they found they
could almost completely control the spread of rice blast, a disease that can
cost the rice industry millions of dollars a year. Known in scientific
circles as exploiting biodiversity for sustainable pest management, the idea
is hardly new to many farmers. But what was new was the cutting-edge science
involved in finally showing farmers how to use this strategy to achieve
In August, experts from around the world traveled to a remote rice-growing
area in China`s southern Yunnan Province to see for themselves just how
successful the IRRI-managed project was-and they didn`t have to go far to
look. Literally thousands of farmers in the province have now embraced the
technique, claiming it not only reduces their reliance on chemicals but also
improves yields and increases their incomes.
It all seems almost too good to be true. But for Dr. Tom Mew, the head of
IRRI`s Entomology and Plant Pathology Division and the project`s
coordinator, it represents the culmination of decades of work trying to help
rice farmers find the best ways to control the pests and diseases that cost
them hundreds of millions of dollars a year.
"When I started at IRRI 25 years ago, the focus was on food security," Dr.
Mew explained. "There was a real danger of people starving back then, so we
focused on increasing production, whatever it took. It was a tough choice,
but we thought food security was the most important goal so we focused on
high-input agriculture that would ensure that everyone got fed."
It was this thinking that led to the Green Revolution of the 1960s and
1970s, which saw massive increases in production and a plentiful supply of
rice for most Asian nations. However, it also saw sharp increases in the use
of fertilizers and pesticides needed to ensure bumper harvests. This was
perhaps the one black mark against an otherwise brilliantly successful
Quite quickly though, scientists like Dr. Mew realized there were many
cleaner, greener ways to control pests and diseases besides the use of
pesticides. By the mid-1980s, the phrase "integrated pest management (IPM)"
had been coined by scientists to describe the way they looked at any
cultural strategy that could control pests and diseases.
"Over the past 10-15 years at IRRI, we have been looking at scores of
different ways to control pests and diseases, all with the aim of reducing
chemical use," Dr. Mew explained. "There are friendly insects that we can
use as part of biological control strategies, as well as the more efficient
use of water and more effective management practices-all these are just a
part of IPM."
While it has not been easy to wean rice farmers from their dependence on
chemicals, other IRRI researchers have achieved notable success in Vietnam.
Their research was based on the premise that farmers` perceptions, rather
than an economic rationale, were behind most of their pest management
decisions. For example, it was believed that farmers generally overestimated
the seriousness of many pests and so sprayed too much.
To combat such mistaken beliefs, the IRRI scientists involved developed
radio dramas supported by leaflets and posters, for airing in Vietnam`s Long
An Province in 1994. Research had shown that spraying in the first 40 days
after sowing was not necessary, so farmers were told it was a waste of
money. They were encouraged to experiment and spray only a part of their
crop to see whether they would lose yield on the part they didn`t spray.
The effects were soon obvious, and by 1997 the campaign had been picked up
by 11 other provincial governments and was reaching about 92 percent of the
Mekong Delta`s 2.3 million farm households. The results became clear with
the analysis in 1999 of intensive surveys.
Insecticide applications had fallen from 3.4 times per farmer per season to
just once, a decrease of 72 percent. The number of farmers who believed that
insecticides would bring higher yields had fallen from 83 percent to 13
percent, and the number who believed that insecticides, as well as killing
rice pests, would kill the natural enemies of the pests had risen from 29
percent to 79 percent.
At the same time, the gross rice output of the Mekong Delta increased from
11 to 14 million tons per year.
One of the leaders of the campaign, IRRI entomologist Dr. Kong Luen Heong,
believes that insecticide use can be further reduced by another 50 percent
without affecting rice production.
Dr. Mew faced the same problems in Yunnan. "They were using huge quantities
of fungicide to combat blast," he said, "sometimes spraying a single crop
six or seven times. We didn`t know what kind of environmental damage that
Three years ago, IRRI began working in the province with the Yunnan
Agricultural University as well as the national agricultural research
systems (NARS) in Thailand, Vietnam, and the Philippines to try to overcome
The scientists reasoned that, in a massive, single-variety rice crop, such
as that grown in the Red River Valley of Yunnan, a single disease such as
blast could easily explode into an epidemic. After the pathogen adapted
itself to the physiology of one plant, it was then ready and able to attack
the remainder of the crop. If there was biodiversity in the crop, however,
and if dissimilar plants surrounded the pathogen, it was unlikely to achieve
a population explosion.
"Our challenge was to simulate a situation in which natural resistance to
pests or diseases was diversified through a varietal deployment strategy in
actual rice farming," Dr. Mew said. "We focused on interplanting or growing
different varieties of rice in the same field. At the beginning, doubt and
But an experiment in 1997 covering a few hectares suggested that
interplanting could achieve 92 to 99 percent control of rice blast as well
as attain an unexpected double success by boosting farmers` yields, which
increased by half a ton to 1 ton per hectare.
In 1998, 812 hectares were planted with hybrid rice and glutinous rice, four
rows of one and one row of the other. The crop was sprayed with fungicide
only once. Yields reached 9 tons of hybrid rice and nearly 1 ton of
glutinous rice per hectare. Even more impressive was the fact that, within
the interplanted crop, the incidence of blast fell to 5 percent from a
common level of 55 percent and the yield loss dropped from 28 percent to
nothing at all.
In 1999, the area grew to 3,342 hectares, and the farmers involved boasted
that interplanting was providing them with about US$150 more income per
hectare. By the end of 2000, the IRRI-Yunnan research team plans to extend
the scheme to cover up to 60,000 hectares and continue to expand it into the
Philippines, Thailand, and other rice-producing nations.
IRRI`s director general, Ronald P. Cantrell, says that this success, coupled
with the earlier work in Vietnam by Dr. Heong, is clear evidence of IRRI`s
and the rice industry`s commitment to ensuring a cleaner, greener
environment. "The days of unsustainable high-input rice production are a
thing of the past," Dr. Cantrell says. "At IRRI, we are focused on
sustainable increases in production that are not only friendly to the
environment but, most importantly, help farmers achieve a better quality of
IRRI, with its headquarters in the Philippines and offices in 11 other
countries, is the world`s leading international rice research and training
center. It is an autonomous, nonprofit institution that is focused on
improving the well-being of present and future generations of rice farmers
and consumers, particularly those with low incomes, while preserving natural
resources. IRRI is part of the Consultative Group on International
Agricultural Research (CGIAR), an association of public and private donor
agencies that funds 16 international research centers.
Future Harvest is a nonprofit organization
that builds awareness and support for food and environmental research for a
world with less poverty, a healthier human family, well-nourished children,
and a better environment. Future Harvest supports research, promotes
partnerships, and sponsors projects that bring the results of research to
rural communities, farmers, and families in Africa, Latin America, and Asia.