False smut infestation in rice has been reported from many places in the State in an alarming proportion. In Cauvery delta zone, the disease has been reported to an extent of 10-20 per cent during kharif and rabi seasons.
Another nameAlso known as Lakshmi disease, it is caused by a fungus and was believed to be an indication of a bumper crop in the year.
Due to the infection, individual grains of the panicle get transformed into greenish spore balls of velvety appearance. Spore balls are small at first growing gradually to reach one cm or more in diameter.
They are slightly flattened, smooth, yellow and are covered by a membrane. The membrane bursts as the result of further growth and the colour of the ball turns orange and later yellowish-green or black.
Under congenial conditions like high moisture or rainfall accompanied by cloudy days during the period between flowering and maturity of grains, the development of false smut is rapid and causes considerable loss.
Yield loss is not only due to the occurrence of the smut balls but also due to increased sterility of kernels adjacent to the smut balls.
The disease not only reduces the yield but also affects the quality of grains or seeds. Prominent high yielding rice varieties like CO 43, CR 1009, ADT 38, ADT 39 and BPT 5204 are found susceptible to this infestation.
Late planting of rice during kharif and rabi seasons,are more susceptible to this problem.
Management— Healthy disease free seeds alone should be used for sowing.
— Seeds should not be taken from false smut affected fields.
— At the time of harvesting, infected plants should be removed and destroyed
— Field bunds and irrigation channels should be kept clean.
— Excess application of nitrogenous fertilizer should be avoided.
— Regular monitoring is very essential. Spraying of copper hydroxide at 2.5 gm per litre of water or propiconazole at 1.0 ml per litre will be more useful.
(Dr .K.Karunanithi is professor, Plant Pathology and Dr.R.Rajendran, Director in charge, Tamil Nadu Rice Research Institute, Aduthurai – 612 01, email: dirtrri@tnau.ac.in, Thanjavur, Tamil Nadu.)
