Disease control for Rice Blast Disease

1. Rice Blast
Magnaporthe grisea

2. Pathogen
• Magnaporthe oryzae or rice blast fungus, causes rice blast
• Members of the Magnaporthe grisea complex also infect other
agriculturally important cereals
• Estimated to destroy enough rice to feed more than 60 million people
• The fungus is known to occur in 85 countries worldwide

3. Symptoms and Signs
• Symptoms can occur on different parts of the plant
• Leaf blast
• Diamond-shape lesions on the leaves
• Characteristic for the quick identification of the disease in the field

5. Cont.
• Collar rot
• Infection on the plant’s neck causes rot
• Can result in a lack of seed filling or collapse of the entire panicle
• The pedicels are infected, seeds may not be produced at all

6. Ecology and
Spread
Infected grasses
Crop residues
Infected seed can be
a source of inoculum

7. Disease cycle
Pathogen infects as a
spore that produces
lesions or spots on parts of
the rice plant such as the
leaf, leaf collar and panicle
Using a structure called
an appressorium, the
pathogen penetrates
Sporulates from the
diseased rice tissue to be
dispersed as
conidiophores
Cycle complete in a week
under favorable conditions
lesion can generate up to
thousands of spores in a
single night.

8. Environment
Long periods of free
moisture where leaf
wetness is required
for infection
High humidity is
high
High relative
humidity and at 77-
82 F
Excessive amount
of nitrogen
fertilization
Drought stress
increase rice
susceptibility to the
pathogen
Extended drain
periods also favor
infection

9. BioControl
• Aspergillus niger (Fungus)
• Trichoderma harzianum (Fungus)
• Streptomyces

10. Streptomyces
• S. vinaceusdrappus
• Inhibited the mycelial growth of M. oryzae by 53.5%
• Streptomyces philanthi
• In Southern Thailand exhibited significant antifungal activity
against M. oryzae (88.73% inhibition of mycelial growth)
Boukaew and Prasertsan (2014)

11. Aspergillus niger
• In the dual culture, 81.32% inhibition percentage of M. oryzae
• pH at level 5.0 and temperature between 21℃ to 29℃ is the optimum
condition for A. niger to produce efficient antifungal metabolites
• Antifungal Metabolites
Oleic Acid, n-Hexadecanoic acid, Hexose, Glycerol, Stearic acid,
Tetradecanoic acid, Dodecanoic acid
(Idan, A. , Sijam, K. , Kadir, J. , Rashid, T. , Awla, H. and Alsultan, W. (2017)

12. Trichoderma
harzianum
Treatment of cultivar with Trichoderma harzianum
Treated seed of rice showed range of mean performance
of seed germination from 86.67 to 96.67%
Trichoderma have positive response on the seed
germination
Reduce the intensity of blast disease of rice
It can be used as effective bio-control measure for rice
blast besides increasing the yield of rice crop
Mathivanan et. al.2006.

13. Management
• Certified seed
• pre-treat seed with hot water or fungicides
• Use of resistant varieties
• Susceptible variety once

14. Cont.
• Proper sanitation measures to reduce inoculum
• Carry out crop rotation, intercropping
• Modify plant density to avoid close spacing
• Provide a balanced nutrition to the rice crop
• Maintain proper flood level for rice to grow