Spots may coalesce to form large, irregular-shaped spots. Severe infection may cause defoliation. Avoid overhead watering. The disease is spread by taking cuttings from infected plants. Use sterilized soil and pots.
Leaves have tan to brown spots up to one-fourth inch in diameter.
Spots are circular and zoned. The disease begins on the older leaves and spreads upward when the plants are watered excessively or when air circulates poorly because of overcrowding. Diseased leaves should be destroyed and sterilized soil should be used. Disease-free plants should be used for propagation. Avoid wetting foliage when watering.