FALSE SMUT OF RICE

FALSE SMUT OF RICE

  1. NAME OF DISEASE AND CO: False smut (Ustilaginoidea  virens).

  2. Host plants: Grasses and Wild rice

 3. Mode of transmission/ dissemination: By wind, air - borne

4.Why and where it occurs:

• Symptoms are visible only after panicle exsertion It can infect the plant during the flowering stage.

• Moderate rainfall with intermittent clear and drizzling weather during flowering.

• Presence high Relative humidity (>90%) ,and temperature ranging from 25−35 ºC.

• Presence of soils with high nitrogen content.

• presence of wind for dissemination of the spores from plant to plant

5. Why is it important:

      False smut causes chalkiness of grains which leads to reduction in grain weight. It also reduces seed germination.

6. Symptoms:

• Visible only after panicle emergence at milk stage.

• Plants infected with false smut have individual rice grain transformed into a mass of spore balls. These spore balls are initially orange, and then turn into greenish black when these mature.

• Individual grains of the panicle are transformed into yellow or greenish velvety spore balls..

• The smut ball appears small at first and grows gradually up to the size of 1 cm. It is seen in between the hulls and encloses the floral parts.

• Only a few grains in a panicle are usually infected and the rest are normal.

• As the fungi growth intensifies, the smut ball bursts and becomes orange then later yellowish-green or greenish-black in color.

• Infection usually occurs during the reproductive and ripening stages.

7. Management: 

    A. Preventive method:

• Growing Resistant variety- Kavya, IR -64, IR- 30864

• Use certified seeds.

• Keep the field clean.

• Use of disease-free seeds that are selected from healthy crop.

• Seed treatment with Carbendazim 2.0 gm /kg of seeds.or Treat seeds at 52°C for 10 min.

• Remove infected seeds, Panicles, and plant debris after harvest.

• Use moderate rates of Nitrogen.

• Where possible, perform conservation tillage and continuous rice cropping.

   B. Cultural Practices:

• Destruction of straw and stubble from infected plants is recommended to reduce the disease.

• Sowing proper time because Early planted crop has less smut balls than the late planted crop.

• Avoid field activities when the plants are wet.

• Field bunds and irrigation channels should be kept clean to eliminate alternate hosts.

• Avoid Excess application of nitrogenous fertilizer.

• At the time of harvesting, diseased plants should be removed and destroyed.

   C. Chemical control: 

Spray any one of the following Fungicide at the time of flowering;

• Mancozeb 75 % w.p. @ 2.5 gram/Lit. Of water (Dithane M-45,Indofil M-45). 

• Chlorothalonil 75 % W.P. @ 2 gm/lit of water (kavach,jatayu,connan,ishaan).

• Trifloxystrobin 50% E.C. @ 1.5 ml/2 lit of water.(commet).