Diseases of Fruit Plantation Medicinal and Aromatic Crops

Bacterial canker

Causal Organism: Xanthomonas campestris pv. viticola (Nayudu ) Dye.

• Bacterium is Gram negative, rod shaped with rounded ends, motile by single polar flagellum.
• In India, the disease was noticed for the first time on Vitis vinifera cv. Anab-e-Shahi at Tirupati (Andhra Pradesh) in 1960.
• The disease appeared in an epiphytotic form during 1984 in Sangali and Solapur districts of Maharashtra on Thompson Seedles grapes. Now the disease has also been noticed in Karnataka, Maharashtra and Tamil Nadu.
Symptoms

• Small irregular water soaked spots appear on leaves, that translucent to light and have a necrotic pinhead sized centre.
• Numerous spots coalesce to form large patches.
• Severely infected leaves defoliated.
• On the stem disease starts as brown black spots around nodes. In advance stage girdling and cracking of nodes occurs.
• Finally it leads to break down of the plant.
Mode of spread and survival

• The alternative hosts are neem, mango and Phyllanthus maderaspatensis
• The bacterium survives in the infected twigs and dry leaves upto 65 days.
• Secondary infection takes place through wind, and rain water splashes
• Disease spreads to distant places by diseased cuttings.
Epidemiology

• A temperature range of 25-300C is favorable for the disease development.
• Free water from dew, irrigation or rain on leaf are more important for pathogenesis.
• The disease frequency is positively correlated with number of rainy days.
Management

• Regular inspection of vineyard and destruction of infected plant materials.
• Use of disease free cuttings and late October pruning are recommended to manage the disease.
• Spraying with Streptocycline (300ppm), starting from two leaf stage up to 70 days is also effective.