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Leaf blight

Phomopsis obscurans

The leaf blight fungus infects all green parts of the plant and rarely causes a soft rot on ripening and ripe fruit. In Minnesota, leaves are most severely infected in shaded patches that have heavy dew or in years with frequent rain events.


three leaves with brown spotted edges

M.Grabowski, UMN Extension

Young round spots caused by leaf blight

close up of tip of leaf with V shaped red and brown spot

M.Grabowski, UMN Extension

Mature leaf blight symptoms with v-shaped leaf infections

close up of strawberry with brown rotten spot

T. McCamant, Northland Community College

Fruit infection by Phomopsis obscurans, leaf blight pathogen

Symptoms on leaves begin with solid reddish-purple spots that develop a tan center as they grow. As the disease progresses leaf spots enlarge to V-shaped lesions with dry brown centers with reddish purple boarders. Severe infections can turn a whole leaflet brown. Fungal spore producing structures appear as black specks that dot the central area of the older lesions. These can be seen with a 10x hand lens.

Stem infections appear as reddish purple round to oval spots that never develop a tan center. Soft, mushy, pink spots form on pink to red fruit. As fruit infections age, the fruit spots become dark brown and dry.

Important biology

The fungus that causes leaf blight overwinters in infected leaves of the strawberry plant or in infected leaf debris in the strawberry patch. Spores are released in response to moist conditions, and are transported to new leaf tissue by splashing water. Fungal spores of leaf blight require periods of extended leaf wetness (> 15 hours) to germinate. The duration of leaf wetness is the critical factor in disease development because spore germination can occur over a wide range of temperatures. Frequent rains, overhead irrigation, and heavy dews favor disease development.



Fungicides are not considered necessary to control leaf blight in home strawberry patches. Cultural practices usually keep this disease from spreading beyond a tolerable level. Although fungicides are available that will reduce leaf blight infection, they would need to be applied regularly throughout the growing season to maintain continual protection of young leaves. This results in a significant cost, in time and resources, to the gardener. In addition, there is little evidence that reducing leaf blight infection through fungicide sprays will increase yield in following years.

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