Angular Leaf Spot of Strawberries
Angular leaf spot (ALS) is a bacterial disease caused by Xanthomonas fragariae, a pathogen highly specific to both the wild and the cultivated strawberry, Fragaria x ananassa.
ALS is an important disease on winter-produced strawberries worldwide, and it is considered a quarantine disease by the European Union. The disease was reported first in the United States in Minnesota in 1960; since then, it has been found in almost all cultivated strawberry areas in the United States. In California, the largest U.S. producer of fresh strawberries, ALS is a minor disease that occurs especially during rainy weather or when overhead sprinkler irrigation is used. Although the disease is considered minor for fruit production fields in California, it is considered a problem for nurseries that export plants to Europe and other countries with quarantine restrictions.
In Florida, ALS is the only strawberry disease caused by a bacterium. The disease can be especially problematic during seasons when overhead irrigation is used many times for freeze protection.