Powdery mildew and downy mildew
There are two different types of powdery mildew. Powdery mildew occurs in warm and dry temperatures, which is why it is often referred to as “fair weather powdery mildew”. Here, the fungus settles mainly on the stems and on the leaf surface. Downy mildew finds ideal conditions, especially in damp weather, and causes very stubborn, white deposits.
Fight powdery mildew naturally
Infested leaves must be removed immediately and either incinerated or disposed of with household waste - under no circumstances should they be composted. Otherwise, the infected plant is sprayed with a milk-water mixture (100 milliliters of whole milk to 900 milliliters of water) or a garlic infusion (pour boiling water over two to three crushed cloves of garlic and steep for at least an hour and then leave to cool). Treatment should be repeated several times.
Tips & Tricks
Chemical pesticides known as fungicides should not be used on herbs intended for consumption, such as rosemary.