Factors affecting the development of fruit rots of brinjal

Role of temperature, relative humidity, fruit age, inoculum age, inoculation methods and inoculum load was determined on the development of fruit rots (Phomopsis, Phytophthora, Colletotrichum and Fusarium spp.) of brinjal (Solanum melongena L.). The post inoculation exposure of brinjal fruits to different treatments viz., temperature, different relative humidity levels, fruit age, inoculum age and inoculum load revealed a significant effect on their reaction to symptom expression and sporulation period. Among three methods of inoculation, maximum rotting of fruits occurred with ‘pin prick method’ followed by cotton swab and spray suspension method. The fruits exposed to 25°C and >90% relative humidity took less time for expression of disease symptoms and sporulation of fungi. Fruits of age 5–15 days were found more susceptible in case of all the pathogens except Colletotrichum capsici where mature fruits were more prone to disease. Seven days old cultures of all the four pathogens were more aggressive as compared with those of other ages. The minimum time for expression of disease symptoms was observed with standard spore suspension of all the four pathogens. Considerable delay in expression of disease symptoms was observed with decrease in inoculum concentration.