Northwest berry Foundation

Management Detail

Powdery Mildew

in Strawberries

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Latin name: Sphaerotheca macularis f. sp. Fragariae


Edges of infected leaflets curl up, exposing undersides that often are reddened and coated with a grayish white powdery mildew fungus. Diseased leaves later turn purplish or red. In irrigated fields, the fungus also may attack fruit. This fungus is favored by conditions that produce high humidity but dry leaves. It is a highly specialized pathogen that forms a close association with the host. Conditions that favor the host also favor the pathogen.



  • In spring and fall, watch for leaflets curling up with a purple red/purple tinge on the undersides with a coating of a grayish powder. 
  • Diseased leaves will later turn a purple color. 
  • If conditions (humid air with dry leaves) continue, the fruit could become infected.
  • Symptoms can often be confused for symptoms of root rot. Powdery Mildew tends to attack vigorous growth whereas root rot usually stunts the growth of weak plants. Powdery mildew symptoms (leaf cupping, purpling around leaf peripherals, and grayish powder on underside of leaves) are always found together.

Cultural Controls:

  • Avoid overhead irrigation.


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


photo by T. Peerbolt


photo by T. Peerbolt

photo by T. Peerbolt



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