A rhododendron is loved for its large, colorful flowers. The leaves are more of a simple accessory. They don't stand out any further. However, if stains spread on them, the overall appearance will be permanently tarnished. Is there more danger?
What causes rhododendron leaf spot and how do you combat it?
Rhododendron leaf spot is caused by various fungal pathogens and shows symptoms such as reddish-brown to black spots on the leaves. To combat it, we recommend removing infected leaves and twigs and taking measures to strengthen the plant.
Causes of stains
If part of the leaf has a different color than usual, it is generally referred to as spots. It doesn't always have to be a serious illness. That's why a careful look is necessary. In summer it could well be sunburn. But various fungal pathogens could just as easily have caused the stains. For example the following copies:
- Cercospora
- Colletorihum,
- Glomerella
- Pestolotia
Although these are different pathogens, they are grouped together under the term leaf spot.
Symptoms of rhododendrons
Leaf spot disease is particularly likely in warm, humid summers. Different spots can appear. Depending on which pathogen is spreading.
- the spot color can be reddish-brown to black
- round but also irregularly shaped spots are possible
- they have a yellow, red or black border
- the leaf spots are still small at the beginning
- they are getting bigger and growing together
- if there is humidity, they may be covered in mold
- some leaf fall may occur
Note:The yellow-flowering hybrid varieties are considered particularly susceptible to leaf spot.
Fighting leaf spot disease
Leaf spot can be effectively controlled if you don't mind using a broad-spectrum “environmentally harmful” fungicide. Unfortunately, there are no known effective home remedies. But this disease does not necessarily have to cause great damage. That's why you can also proceed as follows:
- Pick off and destroy affected leaves
- also dispose of fallen leaves
- cut off and dispose of heavily infected branches
Note:Take a closer look at the undersides of the leaves to see if you can spot yellow-orange spore beds. Then it is not leaf spot disease, but rhododendron rust. The two diseases are often confused with each other.
Preventing another outbreak
Pay a little more attention to the rhododendron the following year. In summer it should only be watered over the root base so that its leaves do not get wet. Also make sure you fertilize as needed so that the plant's vitality does not suffer.
Tip
Leaf spot disease also occurs on hydrangeas, privet, camellia and many other plants. You should also keep an eye on these plants.