Bacterial and viral diseases of rice


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Bacterial and viral diseases of rice

  2. 2. BACTERIAL DISEASES  Bacterial leaf blight of rice  Bacterial leaf streak of rice VIRAL DISEASES:  Rice tungro  Rice Grassy Stunt  Rice Ragged Stunt  Rice yellow mottling
  3. 3. BACTERIAL LEAF BLIGHT  Pathogen: Xanthomonas oryzae pv oryzae  A gram negative, Non-Spore forming rod shaped bacterium with a single polar flagella  A disease known to occur from 1881 and it is more in tarai region of uttarpradesh  It has many alternate hosts like Cyperus rotundus and C.difformis  The bacterium enters through the natural openings like hydathodes, Stomata and wounds Favourable conditions:  Warm temperature(25-30° C), High humidity, rain, deep water, excess fertilisation, Severe winds which cause wounds.
  4. 4. SYMPTOMS  Seedling wilt or kresek  Wavy margins starting from tip to the end of the leaf  Appearance of bacterial ooze that looks like a milky or opaque dewdrop on young lesions early in the morning  If the cut end of leaf is kept in water it becomes turbid because of bacterial ooze.  Yellow discoloration in embryo and endosperm
  5. 5. MANAGEMENT  Secure disease free seed  Avoid clipping of terminal portion of leaf during transplanting  Balanced fertilization, avoid excess N - application  Destruction of Weed hosts  Avoid flow of water from affected fields  Grow tolerant varieties (IR 20, TKM 6).  Spraying streptomycin sulphate @ 500-1000ppm, Copper Oxychloride 0.25%
  6. 6. BACTERIAL LEAF STREAK  Pathogen: Xanthomonas oryzae pv. Oryzicola  The bacteria is non-spore forming rod shaped bacteria  High temperature and humidity favours the disease Symptoms:  Initially, small, dark-green, water-soaked streaks on veins  Lesions turn brown and bacteria ooze out under humid weather.  This disease may mimics with Narrow brown spot(Cercospora jansiana)-Confirmation with Ooze out test
  7. 7. MANAGEMENT  Avoid clipping of seedlings during transplanting.  Balanced fertilization, avoid excess N - application  Destruction of Weedhosts  Avoid flow of water from affected fields  Grow tolerant varieties (IR 20, TKM 6).  Spraying streptomycin sulphate 500-1000ppm
  8. 8. RICE TUNGRO DISEASE  stunting and reduced tillering.  leaves become yellow or orange-yellow  From tip to down with necrotic lesion without wavy margins  Delayed flowering, - panicles small and not completely exerted  Most panicles sterile or partially filled grains  It has two forms Rice Tungro Bacilliform Virus and Rice tungro Spherical Virus.  The Rice tungro bacilliform virus is responsible for Symptom development and the later is for transmission of disease  Transmission is done by GLH
  9. 9. MANAGEMENT  Set up light traps to monitoring and attract vectors  Destruction of weed hosts on bunds  Grow tolerant varieties like Co 45, Co 48, Surekha, Vikramarya, Bharani, IR 36  In epidemic areas follow rotation with pulses or oil seeds.  Use carbofuran 2Kg/20 cent of nursery area  GLH can be controlled by spraying Phosphomidan or Imidachloprid
  10. 10. RICE GRASSY STUNT  Caused by rice grassy stunt virus, a member of tenuivirus  It is transmitted by BPH Symptoms:  Diseased hills are severely stunted with excessive tillering and a very upright growth habit  Diseased hills has a grassy and rosette appearance  Leaves short, narrow, and yellowish green with numerous small rusty spots or patches, which form blotches  They do not produce panicles  The symptom develops 10-20 days after infection  This can be controlled by use of insecticides against the vector and destruction of infected plants
  11. 11. RICE RAGGED STUNT  Infected plants severely stunted during early growth stages of the crop  Leaves short and dark green with serrated edges  Leaf blades twisted at the apex or base, which result in the spiral shape of the leaves gives a ragged appearance  Ragged portions of the leaves are yellow to yellow-brown  Pale yellow colored Vein swellings develop on the leaf blades and sheaths  Swellings pale yellow or white to dark brown  Flag leaves twisted, malformed, and shortened at booting stage  Nodal branches produced at upper nodes  Partially exerted panicles and unfilled grains
  12. 12. CONTROL  Application of insecticides  Use of resistant varieties  Removal of infected plants from the field
  13. 13. RICE YELLOW MOTTLE  This is due to the virus called Rice Yellow Mottle Virus which is a mechanically transmittable virus  This cause disease at early stage of the crop  Cause twisting , mottling with yellow streaks  Stunting also happens  Transmitted by some beetles  Not seen in India  Management by the control of the beetles
  14. 14. THANK YOU