Effect of Chitosan on Disease Control and Yield Parameters of Rambutan (Nephelium Lappaceum L.) Variety Malwana Special

Abstract

Rambutan (Nephelium lappaceum L.) is an extensively grown fruit crop in Sri Lanka. Powdery mildew incited by fungus Oidium nephelii attack young leaves, flowers and immature fruits caused heavy fruit losses in Rambutan. Chitosan is a natural biodegradable de-acetylated form of chitin has been proven to control numerous pre and post-harvest disease on various horticultural commodities. Therefore, the objective of the present study was to investigate the effect of chitosan compounds on control of powdery mildew disease and yield parameters of Rambutan (Nephelium lappaceum L.) variety Malwana Special. Different types of chitosan i.e. chitosan fungicide, chitosan oligomer, copper containing chitosan and wettable sulphur were used as treatments. Based on the green house test results, 40 ppm concentration of chitosan fungicide, chitosan oligomer and Copper chitosan was identified as economically effective concentration for field studies. Field experiment was conducted in WU1 agro ecological zones at Gannoruwa in Central province of Sri Lanka. Experiment was arranged as Randomized Complete Block Design with 8 replicates. Treatments were sprayed by Knapsack sprayer. Disease severity Index of fruits, fruit weight and number of fruits per bunch were recorded at harvesting. Highest fruit weight was recorded in chitosan fungicide treated fruits. Higher number of fruits per bunch was recorded in all tested chitosan and wettable sulphur treated fruits compared to control. Chitosan fungicide (40ppm) and wettable sulphur 80 WP (4000ppm) has equally potential in controlling of powdery mildew pathogen of Rambutan variety Malwana Special.