Northwest berry Foundation

Management Detail

Common Leaf Spot

in Strawberries

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Latin name: Mycosphaerella fragariae(asexual: Ramularia brunnea)


Foliage is at first dark red or purplish, gradually becoming grayish or almost white with age. Fully developed spots are about 0.12 inch in diameter, with a whitish center and reddish margin. They are scattered widely over the leaf surface, reducing leaf function. Infections occur in moist weather and are most severe in spring and fall. Long wet periods (several days) and warm temperatures (over 50°F) favor disease development in the spring and in summer after renovation. 'Olympus' and 'Shuksan' are very susceptible. Puget Reliance also shows significant infections.The fungus also can infect fruit in what is called black seed disease. Spots are brownish black, hard, and leathery. Fruit does not rot but discolors under the spot.



  • Leaf lesions or "spots" are small and round (3-8 mm diameter), dark purple to reddish in color, and are found on the upper leaf surfaces.
  • The center of the spots becomes tan to gray to almost white over time, while the broad margins remain dark purple.
  • Lesion centers on younger leaves stay light brown, with a definite reddish purple to rusty brown margin.
  • Superficial black spots form on ripe berries under moist conditions. These spots surround groups of seeds on the fruit surface. The surrounding tissue becomes brownish black, hard and leathery.

Cultural Controls:

  • Be sure that planting stock is clean.
  • Cultivars differ greatly in their resistance to Common Leaf Spot. If it is a serious problem, use a more resistant cultivar.


For information about chemical controls, check with our Pesticide Guide.


photo by T. Peerbolt


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