This document discusses the rice blast fungus, a fungal disease that is the most severe and infectious disease of rice plants. It first appeared in Japan in 1904 and India in 1913. The pathogen is a type of ascomycota fungi that releases toxins and has both asexual and sexual stages. It is spread by wind and seeds. The disease is managed through cultural practices like removing weeds, soil solarization, resistant varieties, and proper spacing. Biological controls include seed treatments with fungi like Pseudomonas fluorescence and Tricoderma viride. Chemical controls include seed treatments with fungicides and foliar sprays.

1. Rohit Kumar Choudhury
UID-K14993, Sec-F, III rd sem
B.SC agriculture

2. Introduction:-
It is a fungal disease as well as the most
severe and infectious disease of Rice plant. So
It is called Rich men’s Disease.
History of Rice Blast :-
• First appeared in Japan in 1904.
• In India first appeared in Tanjavur city,
Tamilnadu, in 1913. Identified by
E.J Butler.
• Loss exceeds 75%
Distribution in India:- Tamilnadu, Andhra Pradesh Orissa, Chhattisgarh,
Gujarat, Punjab, Uttar Pradesh, Maharashtra etc
Rice Blast( Leaf)

3. About Pathogen:- Ascomycota fungi.
It releases toxins like- Pyricularin , Alpha-
Picolinic acid etc which cause infection.
Asexual stage:-
•Mycelium is Septate and Hyaline (Young
stage) or Olive-Brown (Mature stage)
•Conidiophores are also septate and
produces 7-9 asexual spores called Conidia.
• Conidia are Hyaline to olivaceous and
ellipsoid shaped
sexual stage:-
•It develops sexual fruit body called
Perithecia
•Perithecia consists a number of Ascus, which
contains sexual Ascospore.
Asexual stage (P. gresia)
Sexual stage ( M.gresia)

4. Favorable conditions for the Pathogen:-
•Low night temperature (15-20 0C)
•High relative humidity (> 95%)
•Cloudy and drizzling weather
•Degree of host susceptibility due to the excess use of
Nitrogen.
•Availability of Collateral host.
Mode of transmission/dissemination:- Wind & Seed

5. Asexual spores of Fungus
Conidia
Host plant Rice
Development of
Symptoms in Host plant
Survival of Spores
On Collateral Hosts
Multiplication of Spores
Dispersal through Air and
Water
Over wintering on
Seed and Soil
Inoculation
Penetration
and Infection
Reproduction
Dissemination
Secondary
Infection
Cycle
Primary
Infection
Cycle

6. Leaf Blast Collar blast
Or Rotten neck
Nodal
Blast
Panicle
Blast
•Leaf Blsat
Spindle like
lesion Diamond shaped
lesions

7. •Collar Blast
•Nodal Blast

8. •Panicle blast
Glumes and
Panicles are
affected
Blanking of
rice grains

9. Management of Rice BlastManagement of Rice Blast
Cultural/Mechanical
Physical
Biological
Chemical
NEXT
IPDM

10. Cultural practices:-
•Sanitation of Field and remove collateral weed host.
•Soil solarization.
•Changing the Sowing time to escape from the disease.
•Apply N in three split doses (50:25:25)
•Use resistant variety- CO 47, CO29, IR-64, IR-36, IR-20 etc.
•Avoid stagnating of water in the field
•Maintaining proper spacing and promote summer ploughing.
Biological Control:-
•Seed treatment with Pseudomonas fluorescence 10g / 1 of water .
•Seed treatment with Tricoderma viride 4kg/lit. of water .
Chemical Control:-
•Seed treatment with Thiram or Captan @2.5g/kg of seeds
•Spraying of Mancozeb @0.25%
•Spraying Carbendazim @ 1g/lit. of water