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1. Integrated Disease Management in Rice Dr Satish Chandra
Principal Scientist (Plant Pathology) ICAR Research Complex for NEH Region ,Umiam Meghalaya
2. Major Diseases of Rice Blast (Pyricularia oryzae)
Brown spot (Helminthosporium oryzae)
Sheath blight (Rhizoctonia solani)
Stem rot (Sclerotium oryzae)
Leaf scald (Rhyncosporium oryzae)
False smut (Ustilaginoidea virens)
Bacterial leaf blight (Xanthomonas oryzae)
4. Blast disease Most plant parts are susceptible to infection except the roots.
Disease usually develops during seedling, tillering (leaf blast) and at heading (panicle blast).
The initial infections start as small water soaked areas on young leaves and enlarge into diamond shape with a blue gray cast which are the fungal spores. Lesions often dry out and turn tan with a brown border. Lesion shape and size can vary.
8. Management Blast development is favored by thick stands and high nitrogen rates which increase canopy thickness resulting in higher moisture levels but is most severe under upland or drained conditions. Other conditions that favor blast are sandy soils and fields lined with trees.
9. Management contd. Plant varieties resistant to blast.
Avoid late planting.
Plant as early as possible within the recommended planting period.
For leaf blast, re-flood if field has been drained. Maintain flood at 4 -6 inches to ensure soil is covered.
Do not over fertilize with nitrogen.
Apply a fungicide if necessary.
10. Blast resistant varieties Bhalum1, Bhalum2 for upland
Shasarang and Lampnah for transplanted lowland
11. Brown spot
12. Management of brown spot Treat the seeds with 0.2% Thiram
Avoid water stress
Give balanced nutrition
Use resistant varieties
14. Management of sheath blight Use resistant varieties like Bhalum 1, Bhalum 2,RCPL1-46, RCPL1.14, RCPL1-113.Katak Tara and Garomaloti
Effective fungicides: Carbendazim, Sheathmar, Rhizolex, Tilt etc.
Fungicide applications are typically applied from panicle differentiation to heading. The boot (2-4 inch panicle in the flag leaf sheath) is the most effective timing. Fungicide must be applied no later than 50 -70% heads emerging to be effective.
16. Management Fungicides are available to control stem rot however infestation levels seldom reach economic levels to justify spraying and no economic thresholds have been developed. Stem rot is usually detected when scouting for sheath blight. Fungicide applications targeted at other diseases can reduce stem rot severity.
18. Management Application of higher doses of Potash (80 kg/ha) reduces the diseases.
Spraying of 0.1% carbendazim three times starting from from the appearance of the disease at 15 days interval.
20. Management Spray Tilt (propiconazole) @1% at boot stage.
Fungicides used for managing other rice diseases are also effective against false smut.