Management of false smut infestation in paddy
False smut of rice, once considered as a minor disease, has now become a serious disease in Tamil Nadu and also other rice growing states of India.
For the past three years, the disease incidence has been reported in many places in an alarming proportion.
The disease is caused by a fungus also known as Lakshmi disease of rice. 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.
Affects grain quality
Usually, only a few grains in a panicle get infected. At severe infection, most of the grains in the panicles are affected by the disease. The disease not only reduces the yield but also affects the quality of grains or seeds.
Prominent high yielding rice varieties such as CO:43, CR:1009, ADT:38, ADT:39 and BPT:5204 are also found to be affected by the this infestation.
Due to fungal infection, individual grains of the panicles transform into greenish spore balls of velvety appearance.
Spore balls are small at first growing gradually to reach one cm or more in diameter and enclosing the floral parts. High moisture or rainfall accompanied by cloudy days during the period between flowering and maturity of grains favour the development of false smut.
Management
Healthy seeds or seeds free from sclerotia should alone be used.
Early planted crop has less smut balls than the late planted crop.
At the time of harvesting, diseased plants should be removed and destroyed so that sclerotia do not fall in the field.
This will reduce primary inoculum for the next crop. Field bunds and irrigation channels should be kept clean to eliminate alternate hosts.
Excess application of nitrogenous fertilizer should be avoided.
Regular monitoring of disease incidence during rabi season is very essential.
Spraying of copper oxychloride at 2.5 g/litre or Propiconazole at 1.0 ml/litre at boot leaf and milky stages will be more useful to prevent the fungal infection.
A. Karthikeyan
& S. Jebaraj
Tamil Nadu Rice Research Institute, Aduthurai
Thanjavur , Tamil Nadu
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