Do you tend your garden with great care and yet mildew suddenly appears on the leaves? This may be due to unfavorable temperatures. However, you should not rule out too intensive care. To find out the exact reason for the occurrence of the parasite, learn about the most common causes of powdery mildew below.

Powdery mildew occurs mainly in warm and dry conditions

Powdery mildew is caused by a fungus

In botany, a distinction is made between two types, powdery mildew and powdery mildew. Both diseases are caused by a fungus. As a rule, this pest specializes on a single plant variety. For example, cucumber powdery mildew does not affect roses.

Causes of powdery mildew

Powdery mildew is also known as the "fair weather fungus" because it forms when it is warm and dry. It sits on the upper side of the leaf and is visible through white spots that later form a dirty, brown film. Powdery mildew is mainly found on

  • asters
  • roses
  • cucumbers
  • carrots
  • and gooseberries

Causes of downy mildew

In contrast, downy mildew, the "bad weather fungus" develops when the air humidity is high. The symptoms appear on both the upper and lower surfaces of the leaves, with the film having a purple tinge and the spots being yellowish. Downy mildew mainly attacks

  • cabbage
  • radish
  • salsify
  • peas
  • Lamb's lettuce
  • lettuce
  • spinach
  • radish
  • grapes
  • and onions

Care mistakes that favor powdery mildew

Incorrect watering, fertilizing or planting promote the development of powdery mildew. You should pay attention to this:

  • too much nitrogen promotes fungal growth and weakens the plant's defences. Dose the fertilizer conscientiously
  • when watering, wait until the substrate is dry. Only water the roots, never the leaves, and give the water in the morning if possible. Otherwise the liquid will back up overnight because it does not evaporate. The resulting moisture invites downy mildew
  • Plants that are planted too densely also cause a high level of humidity in the environment, as the air cannot circulate sufficiently

Recurring powdery mildew

Mildew again? You have just completely cut the infested plant. But have you also paid attention to adequate care? Never just throw the affected branches on the compost. From here the fungus spreads to settle on neighboring plants. It is best to burn the diseased shoots or dispose of them in the household waste.

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Care tips