Effect of heat treatment on green mold infection in tangerine fruit cv. Sai Num Pung

Abstract

The effect of heat treatment on Penicillium digitatum infection which caused green mold rot in tangerine fruit cv. Sai Num Pung was studied. Fungus was dipped in hot water at 45±2, 50±2 and 55±2°C for 0.5, 1, 2 and 3 minutes/each treatment. The results showed that hot water dip at 55±2°C for 3 minutes was the best in delaying P. digitatum spore germination when incubated fungus at 25±2°C in darkness for 48 hours. Dipping tangerine fruit in hot water at the temperature and time mentioned above before and after inoculation compared with the control fruits that were inoculated by fungus and without hot water dip and uninoculated fruit reduced disease severity (lesion diameter) from 9.68 cm. to 0.32 cm. Dipping tangerine fruit in hot water at 50±2°C for 3 minutes and 55±2°C for 2 and 3 minutes after inoculation was able to delay disease incidence and severity and reduced sporulation index of P. digitatum when stored at 24±2°C and 90±5% relative humidity for 5 days.