Recognize and differentiate between powdery mildew and downy mildew
- the top of the leaf is always affected
- wipeable, white to dirty brown covering
- Leaves turn brown and dry up
- Fungal lawn always on the underside of the leaf
- gray or gray-violet coating
- Upper side of the leaf shows yellowish lightening
- Leaf slowly dies off
Only downy mildew, which affects the hydrangea more often, can be prevented. Keep the leaves dry by always watering the hydrangea from below. Plant strengtheners based on algae, which you can get in specialist shops, can effectively prevent an infestation.
Control of powdery mildew
- Remove all diseased plant parts and dispose of them with household waste.
- For downy mildew, spray with copper-containing fungicides. Make sure that the undersides of the leaves are wetted.
- Powdery mildew is combated with sulfur-containing products.
- Treat the hydrangea several times as powdery mildew is very persistent.
Tips & Tricks
This fungal attack can also be combated biologically. The lecithin contained in fresh whole milk or whey fights the fungus and can prevent it from spreading further.