Mode of transmission/ dissemination:Soil,Irrigation water
Period of occurrence:The fungus affects the crop from Tillering to Flowering stage.
Why and where it occurs:
Relative humidity of crop canopy from 85−100%.
Temperature from 28-32 °C
high levels of nitrogen fertilizer
High seeding rate or closing plant spacing
Frequent rain or Rainy season.
August to September month mostly occurs.
Symptoms:
Initial symptoms are noticed on leaf sheaths at just above the water level.
Lesions are oval or ellipsoid in shape,about 1 cm.,water-soaked spots which are greenish-gray in color.
Sheath Rot
As the spots spread, the centre or leaf blades becomes greyish white with an irregular blackish brown or purple brown border.
Lesions on the upper parts of plants expand rapidly merge with each other to cover entire tillers from the water line to the flag leaf.
At severe condition drying of leaves.Infected leaves dry out and die more rapidly, young tillers can also be destroyed
If symptoms occur at panicle initiation stage ,impact on grain filling.
Grains also become black in colour and Sticky rice occoure.
Impact on grain filling to the premature death of plants and lodging with a significant reduction in grain yield and quality.
Management:
Preventive method:
Seed treatment with Pseudomonas fluorescens @ of 4g/kg of seed followed by seedling dip @ of 2.5 kg or products/ha dissolved in 100 litres and dipping for 30 minutes.
Soil application of P.fluorescens @ of 2.5 kg/ha after 30 days of transplanting (This product should be mixed with 50 kg of FYM/Sand and then applied.
Foliar spray of Pseudomonas fluorescens at 0.2% concentration ,commencing from 45 days after transplanting at 10 days interval for 3 times depending upon the intensity of disease.
Cultural Practices:
Selecting a rice variety that is less susceptible or moderately resistant to sheath blight.Like: Swarna-dhan,Vikramarya, Radha, Pankaj,Manasarovar, Mandya Vijaya etc.
Avoid using infected seed.
To reduce the rate of nitrogenous fertilizer.
Use reasoned density of crop establishment.(direct seeding or transplanting).
Carefully control of weeds, especially on the levees.
Drain rice fields relatively early in the cropping season to reduce sheath blight epidemics. Check brown plant hopper population
Chemical control:If the disease observed in the field than spray one of the following Fungicide.Control of sheath blight has been mainly through the use of foliar fungicides.
Recommended for spray Validamycin 3% L (SHEATHMAR) @ 3 ml / lit of water.
Recommended For Spray Propiconazole 25% Sc @ 1.5 Ml / 2 Lit Of Water. (Tilt,result,built,squas,remote) or
Recommended For Spray Thifluzamide 24% Sc @ 1.5 Ml / 2 Lit Of Water. Or
Recommended For Spray Flusilazole 40% Ec @ 1 Ml / 2 Lit Of Water or
Recommended For Spray Tricyclazole 34.2% + Propiconazole 10.7% ( 44.9% Sc) @ 1 Ml / Lit. Of Water.(Filia) or
Recommended For Spray Hexaconazole 4% + Zineb 68% (72% Wp) @ 2 Gm / Lit Of Water. (Avtaar)or
Recommended For Spray Tebuconazole 50% + Trifloxystrobin 25% (75% Wg) @ 1.5 Gm / 2 Lit Of Water. (Netivo) or
Recommended For Spray Propiconazole 15% + Difenconzole 15% ( 30% Ec) @ 1.5 Ml / 2 Lit Of Water. (Armiur,nack)or
Recommended For Spray Flusilazole 12.5% + Carbendazim 25% (37.5% Sc) @ 1.5 Gm / Lit Of Water etc.
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