INTRODUCTION OF BIO- FUNGICIDES FOR CONTROLLING POWDERY MILDEW DISEASE OF RAMBUTAN

Abstract

Powdery mildew of Rambutan (Nephelium lappaceum) incited by the fungus Oidium nephelii attack young leaves, flowers and immature fruits become dis-colored and dry off causing fruit quality deterioration and heavy fruit losses.  Oidium nephelii is controlled by application of fungicides. An experiment was conducted  to study the efficacy of plant extracts compared with the  fungicides to control powdery mildew disease of Rambutan. The treatments consisted of eight plant extracts (Neem oil, Citronella oil, Cinnamon leaf extract (Cinnamomum zeylanicum), Clove leaf  extract (Syzygium aromaticum),  Naa leaf extract (Mesua nagassarium), Lime leaf extract (Citrus aurantifolia),  Neem seed extract (Azadiracta indica), Vinegar (Cocos nucifera)) and two recommended fungicides Thiovit (wettable  Sulphur) and  Daconil (Chlorothalonil). Severity and spread of powdery mildew basically depends on the environment. Therefore selection of herbal extracts was done during heavy rain and in dry weather conditions. The results obtained from the experiment revealed that under the dry weather condition, the maximum number of healthy fruit set at harvest was given by the Citronella oil and Neem oil. The Clove leaf extract and Cinnamon leaf extract significantly controlled the powdery mildew disease  than that of Department recommended fungicides .Neem seed extract and Vinegar controlled the disease  similar to the Department recommended fungicides. In contrast to the data obtained under dry weather condition, in the heavy rain conditions, only the Citronella oil and Neem oil moderately increased  the healthy fruit set at harvest. The  plant extracts Neem oil, Citronella oil, Clove leaf extract, Cinnamon leaf extract controlled the disease than that of recommended fungicides and they can be used as the bio-fungicides. Bio-fungicides are eco-friendly and are not known to cause pollution to climate or soil.