1. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
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2. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Major Bacterial & viral Diseases
Bacterial Leaf Streak
Bacterial Leaf Blight
Tungro Virus Disease
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3. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Bacterial Leaf Blight
Local name: Bacteria janita pata dhwasa
Causal Organism: Xanthomonas oryzae pv. oryzae (Ishiyama) Swings et al.
Bacterial Leaf Blight Disease symptoms on paddy
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4. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Epidemiology:
High relative humidity (83-93%) and moderate temperature (26-300C) favour the disease development. .
The disease usually occurs during the early stage of planting from maximum tillering to panicle initiation.
Older plants are more resistant to the disease.
The disease is transmitted through seeds
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5. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Epidemiology:
Infection occur through wounds and stomata.
Infected seeds present in the water or those surviving in the debris left after harvest, are also sources of inoculums in the next planting season.
The disease also disperse and spread by wind and rain water.
High dose of nitrogenous fertilizer, excessive shade and close planting favour the disease.
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6. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Diagnostic Symptoms:
The disease symptoms appear in two phases are leaf blight and wilt or Kresek. .
In susceptible rice varieties lesions may cover entire leaf lamina and even the leaf sheath.
First lesion start as water soaked looking stripes along the margins progressing from top to downwards of the leaf blades.
The margin of the blighted areas is typically wavy in nature
Under wet weather bacterial pathogen exudates and form turbit droplet on the affected portion, after wards bacterial exudates dries up and turn to white encrustation
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7. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Diagnostic Symptoms:
The leaves turn straw yellow, the leaf blight phase generally appears 4 to 6 weeks after transplanting and severe at booting to flowering stage.
Severe infection causes partially filled or chaffy gains and unemerged panicles get rottened.
Systemic infection or Kresek or wilt phase is most destructive, generally causes from early infection.
The diseased leaves roll, droop and wither away.
Sever incidence is noticed from August to November.
Fresh cut out end of the infected leaves show bacterial oozing in clean water.
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8. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Bacterial Leaf Streak
Local name: Dora dag rog
Causal organism: Xanthomonas oryzae pv. oryzicola (Fang et al.) Swings et al.
Bacterial Leaf Streak Disease symptoms on paddy
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9. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Epidemiology:
High relative humidity (83-93%) and moderate temperature ( C) favour the disease development.
The disease usually occurs during the early stage of planting from maximum tillering to panicle initiation.
Older plants are more resistant to the disease.
The disease is transmitted through seeds.
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10. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Epidemiology:
Infection occur through wounds and stomata.
Infected seeds present in the water or those surviving in the debris left after harvest, are also sources of inoculums in the next planting season.
The disease also disperse and spread by wind and rain water.
High dose of nitrogenous fertilizer, excessive shade and close planting favour the disease.
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11. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Diagnostic Symptoms:
Initially, small, dark-green and water-soaked streaks appear on inter veins from tillering to booting stage.
Streaks later enlarge and coalesce to become yellowish gray and translucent patches and cover the entire leaf lamina.
Numerous small yellow beads of bacterial exudates on surface of lesions on humid conditions.
Very small yellow beads instead of bacterial exudates during dry season.
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12. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Diagnostic Symptoms:
Lesions turn brown to grayish white then dry when disease is severe.
Yellow halo symptom appears around the lesions on susceptible cultivars.
Leaves turn brown to grayish white then dry.
At late stages the leaves die and then bleached to grayish white.
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13. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Tungro Virus Disease
Local Name: Tungro virus rog
Causal Organism: Rice Tungro Virus
Vector: Green leaf hopper (Nepltotettix impicticeps, N. virescens,
N. nigropictus)
Rice Tungro Disease symptoms
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14. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Epidemiology:
High nitrogen fertilization had marked influence on development of disease.
The wild species of rice, weed host like Leersia hexandra, Cynenden dactylon, Eleusing indica and Echinochloa colonum are also sucoptible to this disease.
The tungro virus is mainly transmitted by green jassid (Niphotottis Virescens Dist.). It is also transmitted by N. Nigropictus and Racilia dorsalis to same extend.
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15. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Epidemiology:
September to November and March to April the insect vector population is more and active, thus disease is more prevalent in the field.
In Tripura green jassid population is low during the months of January, February, March and December, moderate during the month of April, May, June, August and November, maximum during the month of September and October. So the incidence of disease is also observe to be well correlated with the high population of leaf happer vectors during these months.
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16. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Diagnostic Symptoms:
The characteristic symptoms appear in the field as stunted growth with reduced tillering.
The young leaves turn from normal green to pale green or yellowish green and show mottled appearance alongwith slight twisting.
The older leaves turn orange -yellow and interveinal chlorosis is observed starting from the margin of the leaf blade.
The infected leaves often dry up quickly. In-the field, disease symptoms initially seen in localized spot in yellowing at patches of round nature.
If infection starts at early stage of crop, panicle fail to emerge or bearing chaffy and shriveled grains.
Root development of infected plant is also poor.
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17. DIAGNOSTIC FIELD GUIDE FOR BACTERIAL AND VIRAL DISEASES OF PADDY
Diagnostic Symptoms:
In field the symptoms of tungro are after confused with the symptoms of nitrogen deficiency or cold injury. So to identify the disease in the field one should observe the following points very carefully:-
As the disease if mostly transmitted by green jassid (Niphotottis Virescens) presence of this vector has to be established in the standing rice crop.
In case of cold injury and nitrogen deficient field, yellow colouration of plants will be fairly uniform, but virus infected symptoms usually appear in isolated patches.
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