Onions contain a natural fungicide that helps against fungi such as powdery mildew. However, this is only contained in low concentrations in onions. The highest concentration is found in the tubers. Therefore, the plants can still be affected by mildew fungi.
How do I recognize powdery mildew on onions?
Onions are usually affected by powdery mildew, which is noticeable asgrey-green spots on onion leaves. As the infection progresses, these areas fade more and more and dry up. The leaves are covered in a grey-purple spore lawn.
How dangerous is onion mildew?
The powdery mildew fungus Peronospora destructor can infect not only onionsalso shallots, chives and leeks Infecting the stems reduces the possibility of photosynthesis and the onions are less supplied with nutrients. As a result, the harvest is smaller and the shelf life of the onions is significantly reduced. In the worst case, the plants can die. The fungus appears when there is persistent moisture. Dew formation in the morning hours that does not dry throughout the day promotes the spread of mildew fungus.
How do I treat mildew on onions?
If the downy mildew is only limited to a few bulbs in your garden, you should immediatelydispose of the affected plants Pay attention to all plants that show the damage caused by downy mildew. In the garden, it is best to use home remedies for ecological control of downy mildew. Then water the remaining onions with a decoction of field horsetail. Additionally, you can spray garlic tea on the onion leaves.
How can I prevent powdery mildew on onions?
As early aswhile planting your onions you can prevent mildew by taking the right measures:
- Sowing or cutting as early as possible, before the fungus can take hold
- Observe crop rotation when growing
- Pfer he althy onion sets instead of less productive seeds
- Spatial separation of the different onion varieties and other species susceptible to onion powdery mildew.
During the growing phase, it is best to water in the morning so that the plants can dry out during the day. You should not dispose of plant residues on the bed.
Tip
Resistant varieties
While early varieties are often spared from mildew, summer varieties can already be attacked by the fungi. To protect against an infestation, you can use resistant plants. These include onions of the varieties 'Santero' F1, 'Hylander' F1, 'Bellesco' F1.
