For optimal growth, petunias on the balcony not only need a lot of warmth and light, but also enough water and nutrients. However, despite optimal conditions, there can sometimes be a greater infestation of diseases such as powdery mildew.
Too much moisture can lead to powdery mildew
The downy mildew
Downy mildew can be recognized by its light or brown spots on the upper sides of the leaves and by the mealy coating on the undersides of the leaves. A heavy infestation can lead to the death of the plants. Small infested areas should be cut out immediately to contain the spread. In addition, a location that is as protected from rain as possible should be selected for the petunias. When watering the plants, you should never water the plants as a whole, but always water close to the roots.
The Powdery Mildew
Like downy mildew, powdery mildew is also a fungal disease, but primarily settles on the upper sides of the leaves. The spread of the spores is favored by the alternation between damp and dry phases on the leaves and stems. If the affected areas are not removed, the powdery mildew can not only kill the petunias, but also spread to the following plant species:
- begonias
- dahlias
- cucumbers
- carrots
- salsify
tips
Since downy mildew can also multiply on dead plant parts on the compost heap, cut plant parts should be disposed of with household waste if in doubt.