Recognize and treat leaf spot disease

Causes of stains

If a part of the leaf has a different color than the usual one, it is commonly referred to as spots. It doesn't always have to be a serious illness. That is why a scrutinizing look is necessary. In summer it could well be sunburn. However, different fungal pathogens can just as easily have caused the stains. For example the following copies:

• Cercospora
• Colletorichum,
• Glomerella
• Pestolotia

Although these are different pathogens, they are covered under the term Leaf spot disease summarized.

Symptoms on rhododendrons

Leaf spot disease is to be expected especially in warm, humid summers. Different spots can appear. Depending on which pathogen is spreading.

• the staining can be red-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 get bigger and bigger and grow together
• if there is moisture, they can be covered with mold
• leaf fall can sometimes occur

Note:
The yellow-flowered hybrid varieties are particularly susceptible to leaf spot disease.

Combat leaf spot disease

Leaf spot disease can be effectively combated if you don't mind using a broad spectrum fungicide that is “harmful to the environment”. Unfortunately, there are no known effective home remedies. But this disease does not necessarily have to cause a lot of damage. Therefore you can also proceed as follows:

• Pluck off the infected leaves and destroy them
• also dispose of fallen leaves
• Cut off severely infested branches and dispose of them

Note:
Take a closer look at the undersides of the leaves to see if you can spot yellow-orange spore beds on them. Then it is not about leaf spot disease, but rhododendron rust. The two diseases are often confused with one another.

Prevent another outbreak

Pay a little more attention to the rhododendron in the following year. So it should only be poured over the root base in summer so that its leaves do not get wet. Pay attention to the need-based fertilization so that the vitality of the plant does not suffer.