Impact of Temperature and Humidity on Disease, the Fruit Rot of Two Cultivars of Litchi caused by the B. Theobromi and C. Gloeosporioides

To observe the effect of temperatures and humidity on the fruit rot of two cultivars of Litchi fruits viz, Shahi and China, infected by B. theobromae and C. gloeosporioides, the fruits were incubated at 15, 20, 25, 30, 35 and 40°C and humidity was maintained at 30, 40, 50, 60, 70, 80, 90 and 100 % under artificial conditions. Observation was made at the interval of two days of incubation and upto 10th day. With increase in temperature and with time, the percentage rot in both the cultivars increased. For Shahi, no symptoms at 15°C, 2nd day; 20.5 % rot at 35°C, 6th day; and 100 % rot at 35°C, 10th day, when infected by B. theobromae. And no symptoms at 15°C, 2nd day; 15.5 % rot at 35°C, 2nd day; 16.5 % rot at 35°C, 4th day; 92.5 % rot at 35°C, 6th day; 100 % rot at 35°C, 8th day, when infected by C. gloeosporioides. For China, 34.2 % rot at 35°C, 2nd day; 66.4 % rot at 35°C, 4th day; 100 % at 35°C, 6th day, when infected by B. theobromae. And, 26.4 % rot at 35°C, 2nd day; 55.8 % rot at 35°C, 4th day; and 100 % at 35°C, 6th day, when infected by C. gloeosporioides. It is observed that intensity of fruit rot is influenced by the percentage of relative humidity. Both the Shahi and China cultivars of Litchi fruits infected by B. theobromae and C. gloeosporioides revealed partial rot at low humidity which increased along with the increasing percentage of humidity. Therefore, it was concluded that among the cultivars China was more suitable for the pathogens than Shahi. Similarly, B. theobromae was more virulent than C. gloeosporioides and among the incubation 8th to 10th day was maximum period for maximum rotting and 35°C was the best temperature while 90 - 100 % relative humidity promoted maximum loss.