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MILLETS DOWNY MILDEW
- 1. STUDENT COURSE TEACHER V.S.VIJASHA Dr. S. PARTHASARATHY ID. No. 2016021052 Asst. Prof., (Plant Pathology) COLLEGE OF AGRICULTURAL TECHNOLOGY Affiliated to Tamil Nadu Agricultural University, Coimbatore Kullapuram, Via Vaigai dam, Theni-625 562 MILLETS DOWNY MILDEW
- 2. CAUSAL ORGANISMS HOSTS CAUSAL ORGANISMS Sorghum Peronosclerospora sorghi Pearl millet Sclerospora graminicola Plasmopara penniseti Finger millet Sclerophthora macrospora Foxtail millet Sclerospora graminicola Proso millet Sclerospora graminicola
- 3. SIGNIFICANCE • Millets are the group of highly variable small seeded grasses. • Millets are the important crops in the semiarid tropics of Asia and Africa. Millets are tolerant to drought and other extreme weather conditions. • Downy mildew pathogen is the micro-biotic fungal infection occur in cool moist weather conditions. • It refers to several types of oomyctes microbes that are obligate parasites of plants.
- 4. ECONOMIC LOSSES: • It have a significant economic impact, as infection results in plant death or lack of grain formation in the panicle. • Demonstrated by the epidemics of sorghum downy mildew in Venezuela in the early 1970s, which resulted in the epidemics being declared a national emergency (EI Nacional, Venezula, August 2, in Frederiksen and Renfro,1977).
- 5. • In India, Payak (1975) reported losses of 1,00,000 metric tons due downy mildew incidence in sorghum. • Dramatically recorded in HB 3, popular hybrid, when the pearl millet grain production in India was reduced from 8 milllion tons in 1970-71 to 5.3 million tons in 1971-72. • In certain years it has caused losses upto 50% in the foxtail millets.
- 6. SORGUM DOWNY MILDEW- Pernosclerospora sorghi HISTORY: • P. sorghi was introduced to the America in the mid to late 1950, probably in the Central America region. • It reached the USA in the early 1960 (Reyes et al., 1964). • Subsequently spread to many other countries in Central and South America. • It is widespread in Africa and Asia (Williams, 1984; Jegger et al., 1984)
- 7. DISTRIBUTION: WORLD: Africa, the Indian sub-continent, South- East Asia and North, Central and South America. INDIA: Andhra Pradesh, Delhi, Haryana, Karnataka, Kerala, Madhya Pradesh, Maharastra, Rajasthan and Tamil Nadu.
- 8. GLOBAL DISTRIBUTION OF Pernosclerospora sorghi
- 9. SYMPTOMS: • Symptoms is visible as either systemic and localized infection. • Systemically infected seedling are pale yellow or have light – colour streaking on leaf, chlorotic, stunted and may be die prematurely. • First the symptoms are visible on the lower part of the leaf blade, which later progress upward.
- 10. • The lower surfaces of chlorotic leaves become covered by a white, downy growth consisting of conidia and conidiophores of the pathogen. • The leaves emerging from the whorl subsequently exhibit parallel stripes of vivid green and white tissue. • The infected striped areas die, turn brown, and disintegrate, resulting in a shredded appearance the leaf. • Rectangular shaped local lesion on the leaf.
- 11. DOWNY MILDEW OF SORGHUM © millets.res.in
- 12. PATHOGEN CHARACTERS: • P. sorghi is an obligate parasite systematic in young plant. • The mycelium is intercellular, non –septate. • Sporangiophores emerge through the stomata in single or in cluster and dichotomously branched.
- 13. SEXUAL PHASE: P. sorghi infects susceptible plants though sexual oospores, which survive in the soil. OOSPORES © researchgate.net
- 14. ASEXUAL PHASE: Asexual sporangia which are disseminated by wind. Conidia Mature sporangiophore © researchgate.net © eagri.org
- 15. SYSTEMATIC POSITION: • Domain : Eukaryota • Kingdom : Chromista • Phylum : Oomycota • Class : Oomycetes • Order : Sclerosporales • Family : Sclerosporaceae • Genus : Peronosclerospora • Species : sorghi (W.Weston & Uppal) C.G.Shaw (1978)
- 16. MODE OF SURVIVAL AND SPREAD : • Survive as oospores in host tissue and soil. • Primary infection - soil. • Secondary infection through conidia.
- 17. MANAGEMENT: • Crop rotation with other crops viz., pulses and oilseeds. • Roguing out the infected plants. • Grow moderately resistant varieties like Co25 and Co26. • Seed treatment with Metalaxyl at 6g/kg of seed. • Spray Metalaxyl 500g or Mancozeb 2kg or Ziram 1 kg/ha.
- 18. Sclerospora graminicola HOST: • Pearl millet • Foxtail millet • Prosomillet OTHER NAME : Green ear or leaf shredding
- 19. DISTRIBUTION: This disease is widely distributed in temperate and tropical region of the world and is especially important in India. WORLD: India, China, Japan, Russia, Manchuria and the South- Eastern countries of Europe and America. INDIA Maharastra, Tamil Nadu, Karnataka, Andhra Pradesh, Bihar and Kashmir.
- 20. GLOBAL DISTRIBUTION OF Sclerospora graminicola ©agropedia.iitk.ac.in
- 21. SYMPTOMS PEARL MILLETS: • Symptoms are developed both on the leaves and the ear-head. • Initial symptoms is chlorosis. • Often the lower half of a leaf shows symptoms while its upper half remain symptomless – half leaf symptom. • Numerous sporangia are produced on the lower surface.
- 22. • Infected plant earhead shows the leafy like structures known as green ear disease. • Spikelet tissues are transformed into thread like structure. • Pancile generally does not produce grain. • Leafy growth dries up giving the panicle a dark brown to black appearance. • Lesion symptoms are rare in pearl millet.
- 23. DOWNY MILDEW OF PEARL MILLET © millets.res.in
- 24. FOXTAIL MILLET: • It exhibited by downy growth of the fungal structure. • Shredding of the infected leaves is common during the later stages. • Malformation of floral organs and conversion of few or many spikelet into leafy structure.
- 25. DOWNY MILDEW OF FOXTAIL MILLET © millets.res.in
- 26. PROSO MILLET: • The common symptoms are downy growth on the leaves and leaf shredding. • The green-ear symptoms being mostly absent.
- 27. PATHOGEN CHARACTERS:: Mycelium consists of branched coenocytic intercellular hyphae with small bulbous haustoria. ASEXUAL PHASE: Asexual sporangia germinate to liberate 1 to 12 zoospores. Sporangia generally do not remain viable very long day break. © researchgate.net Sporangia Mature sporangiospores
- 28. SEXUAL PHASE: • Oospores are the thick-walled, spherical and brownish yellow, 22 to 35µm in diameter. • Oospores form in colonized plant tissue can survive from 8 months to 13 years under laboratory conditions. OOSPORES © researchgate.net
- 29. DISEASE CYCLE OF Sclerospora graminicola: © biologydiscussion.com
- 30. SYSTEMATIC POSITION: Domain : Eukaryota Kingdom : Chromista Phylum : Oomycota Class : Oomycetes Order : Sclerosporales Family : Sclerosporaceae Genus : Sclerospora Species : graminicola (Sacc.) J. Schrot., (1886)
- 31. MODE OF SURVIVAL AND SPREAD: • Survive as oospores in host tissues and soil. • Primary infection – soil • Secondary infection - sporangia
- 32. MANAGEMENT: • Resistant varieties for downy mildew of pearl millets are WC-C75, ICMS 7703, ICTP 8203 and ICMV I55. • Seed treatment with Metalaxyl 35% at 6g/kg of seeds. • Foliar application of the Metalaxyl at 3g/l to obtain the disease – free heads.
- 33. Plasmopara penniseti: Host plant : Pearl millet Distribution : Ethiopia SYMPTOMS : • Small ,diffuse water soaked greyish brown stripes or spots expand to irregular brown stripes between veins. • Only local lesions form. Usually lower leaves are affected.
- 34. SYSTEMATIC POSITION : Domain : Eukaryota Kingdom : Chromista Phylum : Oomycota Class : Oomycetes Order : Peronosporales Family : Peronosporaceae Genus : Plasmopara Species : penniseti
- 35. PATHOGEN CHARACTERS: • Sporangiophores emerge from stomata, dichotomously branched irregular monopodially to subdichotomously two or three times at right angles. • Oospores have not been observed.
- 36. Sclerophthora macrospora : HOST RANGE : Finger millet, maize, turf grass etc. OTHER NAME : Crazy top downy mildew HISTORY : • S. macrospora was reported for the first time in India by Venkatarayan (1946) from old Mysore state. • It is also occur in Tamil Nadu and other states in India.
- 37. DISTRIBUTION: WORLD: Africa, Ethiopia, India, China, USSR, Australia, Oceania, Europe, USA, North and South America. INDIA: Bombay, Mysore, Uttar Pradesh and Punjab.
- 38. GLOBAL DISTRIBUTION OF Sclerophthora macrospora © plantwise.org
- 39. SYMPTOMS: • Appearance of bushy and leafy growth in place of fingers or grains. • White cottony growth on the lower surface of the leaf, is generally not seen. • It causes complete sterility. • The proliferation starts at the basal spikelets and gradually the whole ear gives a bush like appearance called green ear symptoms.
- 40. DOWNY MILDEW OF FINGER MILLET © millets.res.in
- 41. TELEOMORPH: Oogonia globose to subglobose, wall thickened, hyaline, 20-48 × 10-29µm, producing oospores filling oogonia. Antheridia hyaline, kidney-shaped, paragynous. Oospores germinate directly to produce zoosporangia. ANAMORPH: Zoosporangia ellipsoid to obovoid, hyaline, apical papillate, 66-114×28-50 µm, germinating in water to release kidney- shaped zoospores with 2 flagella. PATHOGEN CHARACTERS:
- 43. DISEASE CYCLE: DISEASE CYCLE OF Scleropthora macrospora © tnau agriportal
- 44. SYSTEMATIC POSITION: Domain : Eukaryota Kingdom : Chromista Phylum : Oomycota Class : Oomycetes Order : Peronosporales Family : Peronosporaceae Genus : Sclerophthora Species : macrospora (Sacc.) Thirum. (1953)
- 45. MODE OF SURVIVAL AND SPREAD: • Survive as oospores in host tissue, soil and alternate host. • Primary infection – soil • Secondary infection - sporangia
- 46. MANAGEMENT: • Provide good drainage in low lands and proper crop rotation methods. • Seed treatment with organomercurial compounds or Metalaxyl (Apron 35 SD) at the rate 2.5-3.0g/kg would control systemic infection.
- 47. REFERENCES: • Rangaswami.G and A.Mahadevan, fourth edition- 1999. ”Diseases of Crop Plants in India”. PHI Learning Private Limited. Delhi. • Singh, R. S., 2009. Plant Diseases. Oxford and IBH Publishing Co. Pvt. Ltd. New Delhi.