Phytophthora blight

The disease causes sudden death of seedlings. Infected leaves have water-soaked spots that turn brown to black. Infected leaves lose turgidity and finally become desiccated. On stems and leaf petioles the spots are slightly sunken. Affected stems or branches are girdled and foliage above dries up. Plants that are attacked but not killed often form large galls on their stems especially at the edges of spots. Thefungus does not infect the root system. The fungus is soil-borne and it also survives on infected crop debris. The disease is favoured by cool temperatures around 25 degC, cloudy humid weather and rain. Plants develop tolerance to the disease with age.