Leaf spot disease and brown leaves

Leaf spot disease is a fungal disease that causes red, brown or yellowish spots on the leaves of various plants. Should the fungus become more widespread, it is possible that the dark edges of the patches may coalesce, alternatively the leaves may also have holes and thus ensure an unaesthetic overall picture if the disease is not combated become.

The following information and tips provide a good knowledge base on how to prevent or treat leaf spot disease.

The Pest

In order to optimally combat leaf spot disease, the first step is to take a closer look at its causes. The cause of the ugly discoloration is a fungus. These relatives of plants belong to their own subspecies. What is special about them is that they consist of filamentous cells and exist without the leaf pigment chlorophyll. The cells of their host plants serve as nutrients, i.e. they grow into the tissue of the affected plant. Since the plants are deprived of energy in this way, light, brownish spots appear or the affected plant dies.

Backgrounds of the mushroom

The pathogen lives on dead leaves and in the soil, so that there is a higher risk of infection due to the small distance between the fruits/leaves. Symptoms appear after 18 days in warmer temperatures between 16 - 20 °C, they are also promoted by a humidity of over 70%. An infection follows in wetter weather. The spread of the spores is caused by wind and raindrops. A longer-term increase in humidity, for example due to long rainy seasons, therefore represents a simultaneous increased risk of infection with the leaf spot fungus.

differences in plant population

You can minimize the risk of having to deal with leaf spot disease at all by making sure when you buy the plant that you are choosing resistant plants choose. Some species, such as peonies or cucumber varieties, are more resistant to the fungus than others. If a specific species catches your eye, you can ask the retailer for more information.
Plants that often suffer from leaf spot disease are:

• chrysanthemums,
• flame flowers,
• cherry laurel,
• hydrangeas
• or peonies.

In addition, the fungus can also be transmitted to indoor plants. Unfortunately, the fruit trees such as the pear not resistant to the fungus and provide such a popular target. In the case of rhododendrons, for example, infection with leaf spot disease is very easy to recognize, since the yellow to brown spots and spots are quite quickly discolor the rigid, darker leaves through their connection and in the following period also for a partial leaf fall care for.

Control by cutting

Once the leaves are infected with the fungus, they should be removed from the tree immediately. The infected leaves are cut from the branch of the tree using pruning shears. Tip: If the infected tree is very large, only the affected leaves can be removed. Clean tools are of great importance when removing the leaves. In order to prevent the infected fungal tissue from being transmitted through the cutting tool, it is advisable to pre-treat it, e.g. B. disinfected with alcohol. There are also a few things to consider when disposing of the cuttings: Because the leaves are not just the other leaves on the tree, but even the dead leaves in the compost can still be infected, it is advisable to completely remove the cuttings from the garden removed.

Against the fungus with broad spectrum fungicides

The first step here is to remove the affected leaves. After the acutely infected parts have been removed, the remaining parts of the plant can be treated with so-called broad spectrum fungicides. Unfortunately, due to the strength of the fungus, these are usually necessary. Although biological and home remedies can be used to support them, they often do not get to the heart of the problem.

Biological control and home remedies

The most promising protection against leaf spot disease is the purchase of strong plants. Unfortunately, even very resistant plants are not a guaranteed protection, so here are some tips for biological control. A large spatial distance between the different plants has the best preventive effect. General care aspects that influence the condition of the plant also play a role: little light, a lack of nutrients or lack of nutrients. the wrong nutrients, or even sunburn and wrong fertilization increase the chances and wrong of the causative fungus. In the dry season, it is advisable to only water the soil of susceptible plants. This ensures that the leaves are surrounded by the lowest possible humidity, a living environment that prevents leaf spot infestation. Due to the stubbornness of the fungus, home remedies are unfortunately not demonstrably advisable.

Home remedies to build resilience

Instead of chemical fertilizers, it is also possible to strengthen the plants with traditional home remedies:

• Roses can be encouraged by not throwing away the coffee grounds from afternoon coffee, but processing them into the ground.
• The cooking water of the breakfast egg also has another function. Its high mineral content makes it ideal for a new role as a plant fertilizer.
• The remains of a banana peel also have a new purpose. After the hard shell has been crushed with a knife, it can be mixed under the ground and thus provide new energy, especially for indoor plants.
• The use of remains of horn is somewhat more unusual. Horn residues are, for example, fingernails that have been cut off, or hair residues.

frequently asked Questions

Worth knowing about leaf spot shortly

In the case of leaf spots, a distinction must be made as to whether the causes are parasitic, i.e. caused by pathogens (fungi, bacteria, harmful animals) or non-parasitic damage. About 60 percent of leaf spots are caused by fungi. The first symptoms of infestation usually appear in the form of yellow spots. These enlarge rapidly and turn brown in the center. It also often happens that individual leaf spots flow together and the entire leaf is then brown. If the infestation is severe, the leaves may curl up and fall off. The 0.1 mm large, black fruiting bodies of the fungus can be seen on the undersides of the leaves at the infected sites. Important representatives from this group are the fungal genera:

• septoria,
• Phoma,
• ramularia,
• the powdery and downy mildew fungi,
• as well as rust fungi.

prevent fungal infestation

• To prevent fungal infestation, the fallen leaves should be removed, as they contain the spores of the leaf blast fungus, which infect the new leaves in spring. That's why you shouldn't use the leaves in your own garden compost. The temperature reached here is usually not sufficient to kill the pathogens. Affected foliage should be moved to the urban composting be brought or to recycling centers.
• A typical feature of leaf spot disease caused by bacteria is translucent spots or spots surrounded by a light halo. The area is destroyed by bacteria.
• Flowers can also be affected. Bacteria secrete slimy substances that fill the walls between the cells. Especially in wet years there is an increase in bacterial infections, as well as with overhead irrigation. Geraniums are often attacked by bacteria.
• Bacterial infections are transmitted by rain, wind or insects. In most cases, chemical substances have to be used to combat them.

Animal Pests

Animal pathogens that can cause leaf spots include nematodes (roundworms). Leaf nematodes cause dark or red spots with angular borders. Nematodes often transmit viral diseases to plants. When infested with nematodes, in contrast to infestation with fungi, no fungal growth can be seen on the underside of the leaves. The nematodes enter the plant through injuries or the stomata, live in it and feed on the contents of the cells. Damage mainly occurs in wet years, since they need a film of water to move on the plants.
No agents are currently approved in Germany for combating leaf nematodes.

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