13 pages., via online journal., Many rice farmers decide to spray insecticides based on their perception of potential damage and losses caused by pest species. Farmers generally overestimate the seriousness of the rice leaf folder from visible damage and apply insecticides early, and therefore, changing perceptions may help reduce the perceived benefits of unnecessary spraying. Farmers in Long An province, Vietnam, were motivated to ‘test’ a heuristic or rule of thumb, ‘insecticide spraying for leaf folder control in the first 40 days after sowing is not needed’, by the distribution of carefully designed communication media materials. The media reached 97% of the farmers in the study sites. Leaflets, radio drama and posters had the most effective reach. Thirty-one months after the media introduction, the number of insecticide sprays dropped significantly from 3.35 sprays per farmer per season to 1.56. The proportion of farmers spraying at early and late tillering and booting stages was reduced from 59%, 84% and 85% to 0.2%, 19% and 30%, respectively. Those who did not use any insecticides increased from 1% to 32%. Correspondingly, farmers' perceptions of leaf folder damage as indicated in a belief index, decreased significantly from 11.25 to 7.62. The proportion of farmers who believed that leaf folders could cause losses was reduced from 70% to 25%, as did those who believed that early season spraying was required, from 77% to 23%, respectively. Farmers' insecticide spray frequencies and the belief index were significantly correlated and were not significantly different between farmers who had attended farmer field school training and those who had not. The cost (insecticide and labour) saving was the most important incentive for farmers to stop early season spraying as cited by 89% of the farmers. A survey of 12 other districts in Long An showed that 82% of the province's 210000 households were reached. About 20% had not applied any insecticides, 77% had stopped early season spraying and the average number of insecticide sprays was 1.6 (compared with 1.55 in study sites). The approach was readily adopted by extension in 15 provinces that launched their own programmes, extending to the whole Mekong Delta of 2 million farmer households.
