Bacterial leaf blight (Xanthomonas axonopodis)

Symptoms

• Blight refers to the specific symptom of rapid and complete chlorosis, browning, and then death of plant tissues.
• The primary symptoms are small, angular, brown, water-soaked lesions between leaf veins on lower surfaces of leaves
• Later the leaf blades turn brown as the lesion expand.
• Lesions coalesce to form large necrotic patches.
• Defoliation occurs with leaf petioles remaining in horizontal position as leaves drop.
• Dieback of shoots, and brown gum formation on stems, leaves and petioles are also seen.
• Disease spread by water splash and through infected tools.
• It is more severe in wet conditions.

Management

• Use of resistant or tolerant varieties is the only method of control.
• Among improved varieties, H-97, H-226, H-1687 and H-2304 are tolerant to the disease while H-165 is highly susceptible.
• Among the local varieties, M-4 is tolerant to the disease.
• Chemical control is not effective