Management of powdery mildew disease of rambutan (Nephelium lappaceum L.) in Sri Lanka

Powdery mildew disease is the most destructive disease of rambutan in Sri Lanka, which seriously threatens quality fruit production. Therefore, studies were conducted to identify the causal agent, cross infection potential of pathogen with other crops, resistant/tolerant germplasm and safer chemicals for management of powdery mildew of rambutan. Pathogen of powdery mildew of rambutan was identified as Oidium nephelii. Pathogen did not show infection on leaves of rubber, mango, durian and orange which are potential hosts for Oidium species. All germplasm including recommended varieties were susceptible to the disease. Therefore, studies were directed to identify safer chemicals to control the disease. Spraying of wettable sulphur (5g/l.) at young foliage stage, at flowering, just after fruit setting and 3 weeks after fruit setting on to the plants completely controlled mildew disease of rambutan.