Several pathogens of strawberry cause discolored lesions in leaves. Sometimes other plant parts are also affected.
Xanthomonas fragariae
Infected leaves develop irregular, reddish brown
spots on the upper leaf surface that are delimited by major veins. The
lesions may have reddish or yellow margins.
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Diplocarpon earlianum =Marssonina fragariae
Leaf scorch causes brown to purple spots on the
upper leaf of strawberry leaves. Spots typically have an indistinct
border. When infections are abundant the leaf tissue between lesions
commonly becomes bright red to purplish. Spotted leaves eventually turn
brown, dry up, and curl at the margins giving the leaf an overall burnt
or scorched appearance. Infected fruit may develop discolored streaks or
sunken lesions.
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Ramularia tulasnei
The most common cause of spotted strawberry
leaves. Lesions have light brown centers and dark, reddish brown to
purple margins. The spots have a sharply defined border. Spots commonly
grow together to cover much of the leaf surface.
Phomopsis obscurans
Lesions are dark, brown to purplish with pale
centers. Tiny spore-forming structures that appear as black dots can
develop in the center of lesions.
Zythia fragariae
Gray to tan, irregular-shaped lesions generally
appear along the leaflet margins. Numerous, black, tiny, spore-forming
bodies often develop in the leaf lesions. Dark lesions may develop on
the calyx (green cap) of fruit.
