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Blister Blight of tea
What is the causal organism of blister blight of Tea?
Fungus called Exobasidium vexans
What are the symptoms of blister blight of Tea?
Folowing are the symptoms of blister blight of tea
1. Small pale or pinkish circular spots appear on leaves and attain a size of 2.5 cm diameter
2. The spots in the upper surface of the leaf becomes light brown in color and depressed while in under surface of leaf it bulges farming a blister like swelling
3. Lower budget portion is covered with a white powdery growth of fungus
4. When many spots coursers, curling of leaves will occur
5. When it spreads to young succulent stems affected portion are withered
6. The leaf yield is reduced vigor of the tea bush is affected
What are the characteristics of fungus causing blister blight of Tea?
Fungus is the causal organism.
The mycelium is confined to the blistered areas on the leaves
They are septae and collect in bundles below the lower epidermis
Later by rupturing the epidermisa continuous layer of vertical hyphae are projected on the surface of spot
The fungus produces two kind of spores viz.,the conidia and basidiospores
The conidia are most abundant, borne singly at the tip of long stalks
Basidia are formed on the surface in large number but never form a continuous hymenium
What is the Mode of spread and survival of fungus
The fungus completes its life cycle in 11-28 days and several generations of spores are produced in a season
It produces conidia and basidiospores in the same blister
Spores are air borne
The perpetuation of the fungus appears to be form the pre existing infected bushes
What are the Management measures of blister blight of tea?
1. Removal and destruction of the affected portion
2. Spraying with Copper oxychloride 0.25 % in effective
3. Spray with 210 g of COC + 210 g nickel chloride/ha at 5 days interval from June – September and 11 days interval in October – November gives economic control
4. Spraying with systemic insecticides like Atemi 50 SL at 400 ml/ha (or) Baycor (300 EC) at 340 ml/ha a weekly interval is also effective
5. Chlorotalonil, Bayleton, tridemorph is also effective
6. Tridemorph at 340 and 60 ml/ha is satin factory under mild and moderate rainfall condition
Plant pathology – G N Agrios