Effect of Hot Water Treatment on Green Mold Infection in Tangerine Fruit cv. Sai Num Phung

Abstract

The objectives of this study were to examine the optimum temperatures and exposure periods of hot water treatment required to control green mold rot on artificially inoculated tangerine fruit. Preliminary experimentation in vitro, fungus was dipped in hot water at 45±2, 50±2 and 55±2°C  for 0.5, 1, 2 and 3 minutes. The results showed that hot water dip at 55±2°C for 1, 2 and 3 minutes reduced P. digitatum spore germination 85-98% as compared with control when incubated fungus at 25±2°C in darkness for 48 hours at the Laboratory of the Department of Horticulture, Faculty of Agriculture, Chiang Mai University in November 2006. Dipping tangerine fruit in hot water at 45±2 50±2 and 55±2°C for 0.5, 1, 2 and 3 minutes before and after inoculation compared with the control fruit that were inoculated by fungus and without hot water dipped, and uninoculated fruit. Dipping tangerine fruit in hot water at 50±2°C minutes and 55±2°C for 2 and 3 minutes after inoculation reduced green mold rot development 57-88% disease and disease severity (lesion diameter) from 9.31 to 8.07 cm and reduced sporulation index of P. digitatum from 4.32 to 0.18 as compared with control fruit that were inoculated by fungus and without hot water dipped when stored at 24±2°C and 90±5% relative humidity for 5 days.