symptoms ,pathogen and management

1. COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
(Accredited to Indian Council of Agricultural Research, New Delhi)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562
RAGI BLAST
Student Course teacher
Keerthana. R Dr. S. Parthasarathy
2016021017 Assistant Professor (Plant Pathology)

2. INTRODUCTION
Common name : Finger millet (Ragi)
Scientific name : Eleusine coracana
Family : Poaceae
Synonyms : Birds foot, African millet,
Crow footed millet.

3.  Finger millet ia a low cost cereal forms staple food for many African
and Asian countries.
 It ranks fourth among the millets in the world.
 It is widely grown in South India, where it is one of the major staple
food of Karnataka.
 The total area under ragi in India is about 5 million hectares, nearly
40% of which is in Karnataka.
 Over 20 diseases of ragi are known, four of which are important in
India.
S INTRODUCTION

4. S SIGNIFICANCE
 Of the several fungal diseases that affect the finger millet, blast
disease caused Pyricularia grisea is the most important and
destructive disease.
 The disease was reported for the first time in India, from Tanjore
delta of Tamil Nadu by Mc Rae (1920).
 Blast disease is very important among the constraints that affect the
yield, utilization and trade of finger millet within East Africa.
 In Ethiopia, finger millet blast is one of the limiting factors for the
production and yield loss of crop.

5. ECONOMIC LOSSES
 Loss of grain yield may exceed 50% (McRae, 1922).
 Yield losses even upto 80 to 90% in endemic areas.

6. GLOBAL DISTRIBUTION
WORLD:
 India (Mc Rae, 1920)
 Srilanka (Park, 1932)
 Nepal (Thompson,1941)
 Malaya (Burnett, 1949)
 Tanzania (Kuwite and Shao, 1992)
 Somalia (Mohamed, 1980)
 Tanganika (Wallace and Wallace, 1948)
 Zambia (Muyanga and Danial, 1995)
 Ethiopia
 Uganda

7. INDIA:
 Karnataka
 Tamilnadu
 Maharashtra
 Andhra Pradesh
 Odissa
 Bihar
 Uttaranchal

8. SYMPTOMS
 Infection may occur at all stages of plant growth.
 Young seedlings may be blasted or blighted in the nursery bed as
well as developing young plants in the main field.
 There are three stages in disease development.
 Leaf blast
 Node blast
 Neck blast

9. Leaf blast:
 It is more severe in tillering phase.
 The disease is characterized by spindle shaped spots on the
leaves with grey centres surrounded by reddish brown margins.
 Seedlings are more susceptible to leaf blast than mature plants.

10. Leaf Blast
www.apsnet.org

11. L Leaf Blast
agritech.tnau.ac.in

12. Percent leaf blast severity
https://link.springer.com

13. Node blast:
 Infection on stem causes blackening of the nodal region and the
nodes break at the point of infection.
 All the parts above the infected node die.

14. Node Blast
www.agritech.tnau.ac.in

15. Neck blast:
 At flowering stage, the neck just below the earhead is affected and
turns sooty black in colour and usually breaks at this point.
 In early neck infections, the entire earhead becomes chaffy and
there is no grain set at all.
 If grain setting occurs, they are shrivelled and reduced in size.
 Maximum damage is caused by the neck infection.

16. Neck and finger blast
www.runetwork.org

17. Percent Finger blast severity
www.researchgate.net

18. PATHOGEN
Kingdom Fungi
Division Ascomycota
Subdivision Pezizomycotina
Class Sordariomycetes
Subclass Sordariomycetidae
Order Magnaporthales
Family Magnaporthaceae
Genus Pyricularia
Species P. grisea (Cke.) Sacc.(1880)

19.  In Srilanka, Pyricularia grisea has been recorded on Ragi
(Park, 1932).
 In Uganda (Hansford, 1943) and Tanzania (Wallace and Wallace,
1948) identified the pathogen as P. oryzae.
 In India, Ramakrishnan (1948) considered the fungus to be a race of
P. oryzae.
 Wallace (1950) concluded as P. setariae.
 Thirumalachar and Mishra (1954) identified the causal organism as
P. grisea.
PATHOGEN

20. PATHOGEN CHARACTERS
Asexual stage: Pyricularia grisea
Sexual stage: Magnaporthae grisea
Mycelium:
 It may be intra or intercellular.
Hyphae:
 Septate and hyaline when young,
 It turn brownish and may be swollen when older;
 The length of cells vary between 1.5 and 6.0 microns.

21. Conidiophores:
 Simple, septate and dark-colored at the base and lighter above.
Conidia:
 Pyriform shape and sub-hyaline.

22. Conidia and Conidiophores of P. grisea
www.researchgate.net

23. Spores:
 Three celled, the middle cell being broader and darker than the
others;
 It vary in size from 19-31 microns by 10-15 microns.
Chlamydospores:
 Globose, thick-walled, olive brown or dark brown in color, 4 to 10
microns in diameter;
 It may be terminal or intercallary and may also be produced at the
end of germ tubes.

24. EPIDEMIOLOGY
MODE OF SURVIVAL:
 Persistence on alternate hosts such as
Wild Eleusine spp.
Digitaria spp.
Setaria verticillata
 Persistence on collateral hosts such as
Brachiaria mutica
Panicum repens
 The fungus may also persists in plant debris and to some extent
in the shriveled grains from infected ears.

25. MODE OF SPREAD
 The fungus spreads mainly by air-borne conidia.
 Primary spread:
Alternate hosts such as Eleucine indica, Eleusine Africana,
Digitaria spp., Setaria spp., Doctyloterium spp. serves as
primary sources of inoculum.
 Secondary spread:
Air-borne conidia

26. Disease cycle of Pyricularia grisea
www.researchgate.net

27. FAVOURABLE CONDITIONS
 Cloudy skies, frequent rain and drizzles.
 High levels of nitrogen.
 Relative humidity > 90%
 The optimum temperature should be 25-28 °C for pathogen
germination.
 In the tropics, blast spores are present in the air throughout the year,
thus favouring continuous development of the disease.

28. MANAGEMENT
CULTURAL METHOD:
 Use of disease free seeds.
 Proper plant spacing of 40*10 cm or 30*15 cm and
transplanting is advisable.
 Early sowing (July month) reduces the blast severity.
 Practicing crop rotation such as
• Finger Millet - Groundnut - Maize
• Finger Millet - Chickpea - Wheat
• Finger Millet -Cowpea /Pigeonpea – Sorghum.

29. Resistant varieties:
 CO RA (14)
 Paiyur (RA)-2
 GPU-28
 GPU-45
 GPU-48
 L-5
Susceptible variety:
 Indaf 5

30. BIOLOGICAL METHOD
 Spray Pseudomonas fluorescens @ 2 g/lit of water.
First spray immediately after noticing the symptom.
Second and Third sprays at flowering stage @ 15 days
interval.
 Seed treatment with Pseudomonas fluorescens @ 6g/Kg seed and
spray the extracts of
Prosopis juliflora leaf extract (10%)
Ipomoea carnea leaf extract (10%)

31. CHEMICAL METHOD
 Seed treatment with Captan (Captan 50 WP) 4 g or Carbendazim
(Bavistin) 2 g/kg of seeds.
 Spray any one of the fungicides such as Edifenphos (Hinosan) 500
ml or Carbendazim 500 g or Iprobenphos (Kitazin) @ 500 ml/ha.
• First spray immediately after noticing the symptoms.
• Second and third sprays at flowering stage @ 15 days interval
to control neck and finger infection.

32.  Foliar spray with Aureofungin-Sol 100 ppm at 50% earhead
emergence followed by second spray with Mancozeb 1000g/ha
10 days later.
 Spraying of Zineb (Hexathane 75% WP) 1.5 kg/ha.

33. REFERENCES:
 Gupta, V.K., Paul, Y.S., and Sharma Sathish, K. 2012.
Fungi and Plant Diseases. Kalyani publishers, New Delhi.
 Rangaswami, G and Mahadevan, A. 2016. Fourth edition.
Diseases of Crop Plants In India.PHI Learning Pvt Ltd., Delhi.