KẾT QUẢ ĐIỀU TRA MỨC ĐỘ NHIỄM RỆP SÁP TRÊN CÀ PHÊ CHÈ Ở SƠN LA VÀ THỬ NGHIỆM PHÒNG TRỪ BẰNG MỘT SỐ THUỐC HÓA HỌC

Coffee growers in almost Son La coffee areas have not applied major technical measures such as planting, taking care, particularly preventing pests. This report initially showed some survey results on sequence of mealybugs variables, infection rate of mealybugs and the tests for a number of chemical pesticides preventing mealybugs (Planococcus sp) on coffee trees. The investigating result in appearing and developing indicated that most of the coffee growing areas in Son La was damaged by mealybugs, the infection rate started to be occurred in the end of April and then increased rapidly and reached peak numbers in late June and early July then the number of mealybugs gradually reduced. Infected coffee trees and damaged rate by mealybugs on coffee fruits in the garden coffee, with shade trees were higher than the garden without shade trees. In young coffee stage, the rate of infected coffee tree was 10% much lower than mature coffee tree stage (47.89%) whereas Chieng Ban II village, this ratio was 52.2%. The rate of infected fruit bunch in Chieng Ban I village was the lowest among other survey areas, only 39.2%. Different chemical pesticides provided different efficiencies in preventing mealybugs. Out of which, the effect of Suprathion 40EC was the highest (84.7%); followed by Supraxit 40EC (78.84%).