Bacterial leaf blight: Xanthomonas oryzae pv. oryzae (Ishiyama)   Swing et. al.

(Pseudomonadales: Pseudomonadaceae)

Local name: Dundanu Macchhe Roga

Period of occurrence: Tillering to heading stage

Extent of yield loss: 6-60% in extreme cases

Alternate hosts: Grasses (Leersia spp.  & Cyperus rotundus)

Favorable conditions for the pathogen

• Combinations of rainy weather, dull windy days and an atmospheric temperature of 22-26°C
• High doses of N
• Close planting

Mode of transmission/dissemination: Rain splashes (wind borne rain) coupled with wind injuries to rice leaves, irrigation water.

Source of inoculum: Seed, Soil or Plant debris, Alternate hosts. 

Damage symptoms:

• 5-10mm long green-yellow spot at tip of leaves.
• These spots enlarge and turn to yellow.
• It begins as water soaked stripes on the leaf blade.
• Drop of bacterial exudates may be observed on young lesions.

Kresek symptom on Seedling stage	Bacterial Blight of Paddy	Yellow dew drop	Marginal Necrosis

 

Management

Preventive measures:

• Use of resistant varieties - Ajaya, Asha, Biraj, CO-43, Gobind, IR-64,  Janaki, PR-4141, Radha, Sona Mahsuri, Sujata, Suraj, Swarna, Udaya.
• Balanced fertilizer application - Split application of N
• Reduce the disease spread by careful handling of seedlings during transplanting, maintaining shallow water in nurseries, providing good drainage during severe flooding.
• Reduce the amount of inoculum through clean cultivation and drying the fallow fields
•  Remove collateral weed hosts from bunds and channels.
•  Use only disease free seedlings.
•  Avoid excess nitrogen. 
•   Apply N  in three split doses, 50% basal, 25% in tillering phase and 25%N in panicle initiation stage 

Cultural practices:

• Use disease free seeds for sowing.
• Do not use high nitrogenous fertilizer
• Use resistant variety Ajaya, IR 64, Sona Mahsuri, Swarna Radha, Janaki Sujata, PR 4141, Prasad Gobind and Pant Dhan 4  IR-20

                                         

                                                    AJAYA resistant variety

Chemical control: University of Agricultural Sciences, Dharwad.

• Seed treatment with 0.1 g Streptocycline and 0.1 g Copper Sulfate or 0.3 g Agrimycin-100 and 0.1 g Copper Oxychloride in one liter of water for 20 minutes
• Foliar spray of 0.05 g Streptocycline and 0.05 g Copper Sulfate   

Source: UASB, UASD POP & DRR