For years farmers have used chemical pesticides as insurance against the possibility of a devastating crop loss from insect pests and diseases. As long as it was profitable, spraying was a good investment.
But an over-reliance on the use of agrochemicals has resulted in the emergence of pests and diseases that have built up resistance to the very agrochemicals that once killed them. And the insects which were once the natural enemies of the insect pests were also killed or made harmless by the sprays. Scientists refer to farmers being caught in this situation of using more chemicals, more frequently and with less results as being trapped on the "pesticide treadmill."
In many areas the use of chemical pesticides -- often improperly applied and containing compounds banned in many industrialized countries -- not only endanger farmers and consumers, but entire environments.
This "chemical culture" that has arisen among farmers in the Andean regions of Colombia, Ecuador, and Peru, has resulted in higher production costs and threatens the sustainability of agriculture development throughout the area.
At the International Center for Tropical Agriculture (CIAT) in Cali, Colombia, entomologist Cesar Cardona is heading a project that aims to reduce pesticide use on common beans using integrated pest management (IPM) systems. These IPM techniques are being developed jointly by CIAT, its national research partners, and farmers. IPM is an ecologically reliable system that combines various pest control methods, such as use of natural enemies, cropping patterns, and other biological controls, but also includes the careful and controlled use of chemical pesticides. A proper IPM strategy enables farmers to obtain the same yield as with current practices, but at a lower cost.
Cardona says in some areas of Colombia, bean growers spray the crop an average of 11 times during the three-month growing season. "Farmers spray more out of habit and fear than need," he says. Researchers find in many cases farmers are spraying against insects that don't even affect yield. "Even so," Cardona says, "farmers persist because they see pesticides as an insurance policy against crop loss. If farmers used IPM techniques, they could cut their pesticide applications to only two or three per crop in some regions." According to project surveys, between 13 and 30 percent of bean producers have experienced poisoning by pesticides in the last ten years.
The key to success lies in farmer participation. In the Colombia's Antioquia department, for example, farmerrs have found that burning crop residues drastically reduces pest populations. In Ecuador farmers are also learning simple but precise ways to determine when pest populations are strong enough to warrant spraying.
Farmers participating in an IPM experiment divide their farm into two areas. On one they follow their current pest control practices. On the other they apply IPM strategies. At harvest researchers and farmers compare results from the two areas.
To date, the project has conducted about 120 experiments. "In all these trials," Cardona says, "yields with IPM have been the same or greater than with current practices, but with a 70 percent reduction in the use of pesticides."
(CIAT news release)
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