1. BACTERIAL AND VIRAL DISEASES OF
RICE
-J.Delince

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. 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.

5. 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

6. 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%

7. 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

8. 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

9. 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

11. 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

12. 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

14. 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

15. CONTROL
 Application of insecticides
 Use of resistant varieties
 Removal of infected plants from the
field

16. 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

17. THANK YOU