A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1999

Tea is the principal crop and main resource income of the people in upland area in northern Vietnam. Tea plant has been grown as perennial crop in upland area so its attacked by many pests. Red spider mite (Oligonychus coffeae, Acarinae: Tetranychus) is one of the most damaging tea pest in northern Vietnam. The current tea management strategies heavily depend on chemical means. The chemical with strong effect to the pests but also give negative effect to natural enemies and human health as well. In this context, the current study was done to find out the possibility to control red spider mite by biological control. In this study, population of red spider mite and natural enemies were assessment from 5 farmers fields. It was showed that the density of red spider mite was higher in the fields with has not applied neither irrigated nor shade trees. The red spider mite population was observed correlated with rainfall, it normally high level of the density in dry weather condition. The predatory spider (Araneae order), two beetles (Coccinellidae and Staphylinidea) and predator mite (Phytoseiidea) which observed in the fields as well as in the laboratory were effectiveness in order to control red spider mite. The effectiveness of pesticide propargite (COMITE 75 EC) was studied both in the fields and in the laboratory. This result was shown that this pesticide has strong effect not only to the red spider mite but also to the predators. Results from survey involving farmers, extension and plant protection officers showed that the current farmers' practiced for controlling red spider mite was mainly chemical pesticide, followed by IPM (Integrated Pest Management) practice, and cultural practices. The majority of the farmers in study area spray pesticide without recommended from officers and they harvested after spray less than 20 days, The IPM program has been disseminated by officers and its interested by number of farmer 82% in the study area and 48% in whole province.