Leaves curl upward and have a white powder on the leaf underside.
Powdery mildew grows on the undersides of leaves, causing them to curl upwards. Often a whitish “powder” can be seen on the undersides of leaves.
![Powdery mildew on strawberry. Strawberry leaf underside that is mostly obscured by a white, powdery coating. There is a cluster of several small black splotches growing in the white powder.](https://blogs.cornell.edu/berrytool/files/2017/01/strpm28-opt-1ae1abe.jpg)
In severe cases, the fungus may cover the upper surface of the leaves as well. Occasionally, the edges of leaves turn reddish purple.
The disease is spread to new leaves by airborne spores called conidia.
![Microscopic image showing a green, sticklike rod with several white circles attached to it. The white circles resemble soap bubbles and are relatively uniform in size.](https://blogs.cornell.edu/berrytool/files/2017/01/strpm10-opt-wwj0b4.jpg)
Later in the season (August – September), small black fruiting bodies (cleistothecia) may be visible on the leaf lower surface. The fungus oberwinters as cleistothecia on dead leaves.
![Microscopic image of dark brown and black spheres on underside of strawberry leaf. Spheres appear to be attached to bottom of leaf, and do not have visible stem. Spheres somewhat resemble insect eggs or frass (insect poop).](https://blogs.cornell.edu/berrytool/files/2017/01/strpm03-opt-284x9wz.jpg)
In some instances, the fungus may infect the fruit stems…
…or fruit itself.
The most susceptible strawberry variety grown in the Northeast is ‘Earliglow’, but day-neutral varieties are susceptible as well.
A first year planting of ‘Jewel’ strawberry heavily infected in early July.
More strawberry powdery mildew information:
- Strawberry Diseases: Botrytis Fruit Rot & Powdery Mildew – (University of Florida)
- Strawberry Powdery Mildew – (UC Davis)
- Strawberry Powdery Mildew – (Oregon State University)
Use these resources if you need additional help with diagnosis and to find solutions to your problem.