Disease of Tea, Blister Blight, Red Rust and Stem Canker with Symptoms, Favourable condition and Control measures

Disease of Tea 

Blister Blight. https://cststudy.blogspot.com

Blister Blight 

Causal organism: Exobasidium vexans.

Symptoms 

1. Brown to pink lesions developed on the upper surface of leaves. They become circular, blister like swelling both surface of leaf. 

2. Lesion color will be deep red. 

3. The concave symptom is depressed and become white, soft. 

4. Such type of lesions coalesce together formed a bigger lesion and finally leaves may drop off.

Disease Cycle

Fig: Disease Cycle of Blister blight of Tea

Source of Infection 

Source of primary infection, the pathogen remain in the infected bush on the collateral host or form the soil. Secondary infection is made by air, rain splash. 

Favourable condition 

·         High relative humidity (greater than 85%). 

·         Frequent rainfall. 

·         Strong wind. 

·         Movement of labour during harvesting. 

Control Measure 

·         Removal of infected branches by pruning. 

·         Field sanitation. 

·         Soil drench will be made in seedling line. 4 g/m2 plant vax usually 2 times in 2-­3 weeks interval. 

·         After each Plucking, fungicidal (specially Copper fungicides) spray would be done at 10­-15 days interval. 

·         Spraying with Vitavax­200 @ 5-­10 g/mature plant at 35-­40 days interval.

Red Rust 

Causal organism: Cephaleurous parasiticus (Algal disease).

Symptoms  

1. Rusty lesions developed on the leaves. They are roundish in shape. 

2. Reddish hairs like structure develops on the leaves. 

Red Rust. https://cststudy.blogspot.com

Favourable condition 

·         Bright sunshine. 

·         Disease emergence favored by high temperature and humidity.

Control Measures 

·         By obstruct sunshine with the help of shed trees. 

·         Skillful pruning and plucking of bud leaf. 

·         Provide adequate space between plants to maximize air circulation around foliage. 

·         2% MoP and Urea can be sprayed as a rehabilitary measure in the severely affected sections.  

·         Spraying of fungicides should be directed towards the young stems and laterals bearing rusty fructifications.

Stem Canker 

Causal organism: Macrophoma theicola.

Symptoms 

1. At the initial stage, a discolouration is produced on the leaf. 

2. The cork is removed and the wood become visible. In this stage, the mycelia are already inside the cambium region. 

3. In cross section, the channel of discolouration is found along the cambium region. 

Stem Canker. https://cststudy.blogspot.com

Favourable condition 

·         High relative humidity (greater than 85%). 

·         Frequent rainfall. 

·         Strong wind. 

·         Movement of labour during harvesting. 

·         Hail storm.

Control measures 

·         Removal of infected branches by pruning. 

·         Field sanitation. 

·         Pruning infected shoot and applying paint on the cut surface.

·         Spraying Cupravit/Macuprax/Dithane M­45 @ 0.2­0.3% solution @ 800-­1000 gallons/ha  at 21 days interval until the disease is significantly reduced.