Geraniums - which are actually botanically correct called pelargoniums - are popular balcony flowers, but are quite susceptible to various diseases, mostly caused by bacteria or fungi, especially if they are not cared for properly. In the following article you will learn what signs you should look out for and what you can do about them.
Which diseases commonly occur in geraniums and what are the causes?
Typical diseases of geraniums are geranium rust, gray rot and wilt, usually caused by incorrect watering, too much moisture or injuries. Yellow leaves indicate a nutrient deficiency, which can be remedied with iron fertilizer.
pelargonium rust
Geranium or geranium rust is very common on geraniums and is caused by fungi that get on the leaves with rain or rainwater. You can recognize this disease by brown leaves on the upper side of the leaves, while the underside is affected by brown and yellow pustules. Pelargonium rust is highly contagious, so you should separate affected plants as quickly as possible and remove affected plant parts. However, you can prevent the disease by protecting your geraniums from rain and only watering the soil and never the leaves.
Gray rot
Grey rot (often referred to as gray mold or botrytis) is also very common on geraniums. Another similarity is that gray rot, like geranium rust, is caused by excessive moisture. Infected plants have blackish spots and/or grayish fungal growths, especially on the leaves. Sometimes, however, the geraniums simply rot. In addition to excessive moisture, there are other causes of gray rot:
- Lack of light (wrong location)
- incorrect watering
- rainy-cool weather
- Injuries to the plant (e.g. due to pruning)
As with geranium rust, you can prevent gray rot by always watering the geraniums directly onto the substrate, but never onto the leaves, and by protecting the plants well from rain. Treatment is possible primarily by removing affected plant parts in a timely manner.
Wilt
Wilt caused by bacteria is also highly contagious and requires separating affected plants. This disease is mainly caused by
- wet leaves
- excessive watering
- excessive fertilizing
- as well as injuries to leaves and shoots
caused - as with the two diseases mentioned above. As with these, you can also prevent bacterial wilt by protecting your geraniums
- place as sunny and sheltered as possible
- protect from constant rain
- water and fertilize properly
- never water on the leaves
- Avoid waterlogging
- and only use sharp and clean tools for cutting.
Wilt is characterized by the wilting of affected parts of the plant, their turning black and ultimately the death of the entire plant.
Yellow leaves on geraniums
Unlike the diseases described previously, yellow leaves on your geraniums are rarely caused by fungi or bacteria, but usually by inadequate nutrition. In other words, your geraniums are suffering from a nutrient deficiency; It is usually the trace element iron that the plants lack. You can quickly remedy this deficiency with a special iron fertilizer (€17.00 on Amazon).
Tip
If your geraniums only want to produce few or no flowers at all, this is often due to an insufficient supply of nutrients - but not in every case. Often you fertilize enough, but with the wrong fertilizer. If this contains too much nitrogen, leaf growth in particular is stimulated and flowers no longer have room.
