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Usually in the summer after the first harvest, the leaves of strawberry plants are curled up from the side in a spoon shape. Shortly thereafter, small white spots, the fungal mycelia, are discolored purple on the underside of the leaves. The white coating typical of powdery mildew fungi is often barely visible due to the heavy leaf hairs. Strawberry varieties that are susceptible to infestation also show infestation on the fruit. Especially when grown under glass and film, powdery mildew can cause major problems. The powdery mildew fungus also affects flowers and fruits. Blossom rejection, fruit malformation, lackluster and smaller fruits that do not ripen are the result. Fruits that are sensitive to pressure become mushy and slightly leathery quickly.

Powdery mildew on strawberries is favored by stagnant growth, drought, and inadequate water supply to weakened plants. Prevent infestation with a wide plant population. It makes sense to remove old foliage immediately after harvest. If possible, mow down yielding plants immediately after harvest. Individual varieties have different susceptibilities to powdery mildew. Prefer strawberry varieties that are resistant to powdery mildew. Light and soft-leaved varieties are more susceptible than dark-leaved varieties with thicker foliage. 

If powdery mildew symptoms appear around the perimeter on weeds, for example, pay increased attention. Among other weeds, the strawberry cinquefoil Potentilla is also a host plant of Podosphaera aphanis. Proper weed control also prevents powdery mildew infestations.

In strawberry crops grown in tunnels or greenhouses, plants in drafts in particular provide easy targets for the fungus. With a good choice of cultivars, you can significantly minimize the risk of infestation, especially on areas susceptible to wind and in tunnels. 
Continuous irrigation reduces the risk of drought-loving powdery mildew on strawberries. Longer periods of irrigation or rain provide constant moisture and offer spores spread by wind hardly any attack surfaces.Make sure that your strawberry plants are properly nourished, as poorly nourished plants are more prone to disease. By fertilizing regularly, the plants become more resistant.  

The chemical control of powdery mildew on strawberries should be based on the respective approval situation and be discusssed at the consultation. The fungicide treatments should be carried out as soon as the infestation begins. The active ingredient should be changed consistently in order to prevent the development of resistance. 

Greenhouse hygiene is of great importance. Clear harvested areas as quickly as possible. Rapid removal of infested plant parts reduces the number of spores that can overwinter in the strawberry rhizomes. Overhanging vines in substrate crops should also be removed quickly as they pose a risk of infection. 
Condensation moisture on plants promotes powdery mildew infestation. Therefore, heat crops in greenhouses early in the morning to reduce humidity. 

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