Development of screening technique for artificial creation of false smut in rice

Abstract

False smut (Ustilaginoidea virens (Cooke) Takahashi) of rice is an emerging disease and a potential threat to rice growers in different countries due to reduction in yield, quality and production of mycotoxins. Development and cultivation of resistant varieties is desirable approach for its management. Different inoculation techniques viz. spray inoculation, syringe inoculation and dusting method were evaluated for creating artificial epiphytotic conditions in susceptible variety PR116 under natural as well as artificially provided humidity conditions. Spray inoculation method produced more number of smut balls per plant (3.21) and per cent infected panicles (33.44%) followed by syringe inoculation (2.00 and 26.57%, respectively) and dusting method (0.33 and 6.67%, respectively). However, syringe inoculation method produced more spikelet sterility (14.82%) in rice panicles. More disease occurrence was reported in plants provided with artificial humidity after inoculations (51.12% infected panicles) than the plants grown under natural conditions (13.33% infected panicles). Late transplanted crop developed higher disease severity (18.17% infected panicles and 3.34 smut balls/plant) which might be attributed by slight decrease in temperature and increase in relative humidity conditions (up to 88% RH) at time of infection from boot to early flowering stage of the rice crop.