Los Baños, Philippines
September 25, 2000

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 progressed.

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 maximum effect.

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 strategy.

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 was causing."

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 problem.

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 skepticism existed."

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 life."

Company news release
N3308