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July 2008. The hilly Monduiri province of Cambodia is having problems with rice insects. The rice is grown dryland on hillsides, planted in fields no larger than a hectare and separated by forest; the rice is not sprayed with pesticides and there are ants, lady beetles and other predators. There are also a lot of flying/hopping insects about 2mm long of various colours in the crop feeding on plant sap. It is thought that they are a mixture of brown plant hopper and its relatives. Two years ago this problem cropped up for the first time that anyone can remember and wiped out the crop in that whole district. Last year there was no problem, but the plantings were light through lack of seed; now it looks like starting again. Can anyone suggest an appropriate insecticide to reduce losses and an IPM program for the future?
A member from MAFF, Cambodia, confirmed that it was the brown plant hopper, long winged form. The Ministry recommends that farmers use diesel mmixed with sand (just make the sand moist) and that this is broadcast in the rice field. Afterwards, tap the rice plants so that the BPH drop on the water (if the rich is grown in paddies) and use a net to collect them. MAFF does not recommend pesticide: it can cause resurgence of the population after the death of natural enemies and make the situation worse.
In the Philippines, an IPM approach employs different strategies, for instance, synchronous planting, botanical pesticides, resistant varieties (if available), wider distacne, proper nutrient management and, most important, AESA or agroecosystem analysis. With AESA, regular weekly monitoring of the paddies is done, the number of insect pests and natural enemies (biocontrol agents) such as spiders, waterbug, carabid beetles, metioche cricket, dragon flies, damsel flies and many more that are usually found when insecticide usage is on a needs only basis. Ducks were also mentioned as good biocontrol agents. Insecticides should be used only in combination with other IPM measures.
It was suggested that Cambodia contact the Directorate of Food Crop Protection, Jl. AUP, Pasar Minggu, Jakarta Selatan, Indonesia to learn more about IPM control of the brown plant hopper. IRRI should also be contacted.
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