Diseases of Fruit Plantation Medicinal and Aromatic Crops

Red rust

Causal organism: Cephaleuros virescens

• This disease is exceptionally severe in guava.
Symptoms

• The alga produces specks or big patches on the leaves. These may be crowded or scattered.
• The pathogen extends between cuticle and epidermis and penetrates the epidermal cells.
• Fruit infection by alga is not common on fruits. Fruit lesions are usually smaller than leaf spots.
• They are dark green to brown or black in colour.
• Primary source of inoculum: Dormant mycelia
• Secondary source of inoculum: Zoospores

Mode of spread

• The disease is more common on closely planted mother plants. The zoospores cause the initial infection.
• High moist condition favours the development of fruiting bodies of the alga.

Management

• This algal disease is controlled by spraying with Bordeaux mixture (1.0 per cent) or copper oxychloride (0.3 per cent).