Widespread distribution. On citrus including grapefruit, kumquat, lemon, lime, mandarin, orange, pomelo and tangerine, as well as other genera in the citrus family. An important disease.
Bacterial spots on both sides of leaves and fruit causing them to fall early. Fruit unsightly. Spots up to 10 mm, with haloes on the leaves. Cankers cause twig dieback.
Worse on grapefruit, lemon, lime and sweet orange.
Spreads in wind-driven rain, water splash, and nursery plants. Enters through natural openings, wounds (e.g., leafminers). Survival is in leaf litter, and weeds.
Cultural control: ensure nursery is canker-free; keep out of orchard when leaves wet; plant windbreaks around and between rows; Valencia orange and mandarin tolerant.
Chemical control: 2-3 copper fungicide sprays 3 weeks apart, beginning when fruits are about 5 mm diameter.