DISEASE OF FIELD CROPS

1. RICE BLAST
Presented By,
Preethi Aakunuri

2. Introduction
Causal organism – Pyricularia oryzae
Imperfect stage – Pyricularia grisea
Perfect stage – Magnaporthe grisea

3. Symptoms
Symptoms in
Rice Blast
Leaf Blast Neck BlastCollarBlast

4. Symptoms
Leaf Blast
• The lesions are elliptical or spindle shaped with brown borders and
gray center

5. Symptoms
Collar Blast
• Occurs when the pathogen infects the collar
that can ultimately kill the entire leaf blade

6. Symptoms
Neck Blast
• Occurs when the pathogen infects the neck of the panicle
• The infected neck is grinded by a grayish brown lesion
and the panicle falls over if the infection is severe
• If neck blast occurs before the milk stage, the entire
panicle may die prematurely , leaving it white and
completely unfilled

7. Etiology
• Casual organism was first detected by cavara in 1891 from Italy
• Mycelium of the fungus is hyaline to olivaceous separate & highly branched
• Conidia are produced into clusters on long septate, olivaceous slender conidiophores
• Conidia are pyriform to obclavate or top shaped
• Usually 3 celled by 2 septate
• Conidia is Olive green to golden brown colour

8. Disease cycle

9. Favorable condition
Factors favorable for blast :
• Upland conditions
• Extended dew periods
• High relative humidity
• High nitrogen fertilizers
• Intermittent rain showers or drizzle

10. Management practices
• Use of resistant cultivars Viz, Co43, Co47, ADT36, ADT39
• Destruction of diseased crop debris & weed hosts from bunds and channels
• Chemical
- Edifenphos @ 0.1% (or) Tricyclazole @ 0.6%
• Biological :
- Trichoderma viridae @4g/kg (or) pseudomonas fluorescence @10g/kg

11. THANK YOU