Symptoms and Signs
Strawberry leaf blotch is most often found early in the season following heavy rainfall. Symptoms consist of tan to gray lesions that quickly expand from the leaf margins on the first few leaves of the new plant. The lesions, which most often begin at leaflet margins, can grow to cover the entire leaflet surface. The presence of very small black to brown fruiting bodies inside the lesions is a diagnostic sign of this disease. This pathogen can also cause black to brown lesions on the petiole, as well as a brown blight of the calyx and decay on the calyx end of the strawberry fruit.
Comments on the Disease
Zythia fragariae is dependent on splashing water for spread of inoculum, and the disease is therefore much more common in winter and early spring. This pathogen survives on strawberry residue in the soil and most likely will not persist in the absence of this residue.
Leaf blotch has been a minor problem in California, and strawberry plants grow out of this disease when the winter rains stop. Fungicide applications are not recommended.