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Leaf spot disease is a fungal disease-causing disease that is responsible for red, brown or yellowish spots on the leaves of different plants. If the fungus spreads more widely, it is possible that the dark edges of the patches may combine, alternatively, the leaves may have holes and thus provide an unaesthetic overall picture, should the disease not be combated.
The following information and tips provide you with a good knowledge base on how to prevent or treat the leaf blotch disease.
In order to fight the leaf spot disease optimally, it is a first step to take a closer look at its causes. The cause of the ugly discoloration is a fungus. These relatives of the plants belong to a separate subspecies. What is special is that they consist of filamentous cells and exist without the leaf pigment chlorophyll. The cells of their host plants serve as nutrients, ie they grow into the tissue of the infected plant. As the plants are so deprived of energy, it comes to light, brownish spots or the death of the infected plant.
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 short distance between the fruits / leaves. Symptoms occur after 18 days in warmer temperatures between 16 - 20° C, they are also promoted by a humidity of over 70%. Contagion thus follows in damp weather. The spreading of the spores is caused by wind and raindrops. A long-term increased humidity, for example by long rainy seasons, so there is a simultaneous increased risk of infection with the leaf fungus there.
Differences in plant life
The danger of having to deal with the leaf spot disease can keep you small by making sure that you select resistant plants when you buy the plant. Some species, such as peonies or cucumbers, are more resistant to the fungus than others. If you find a special way in the eye, you can ask the dealer for more information.
Plants that are often suffering from leaf blotch disease:
- Cherry laurel,
- or peonies.
Once the leaves are infected with the fungus they should be removed from the tree immediately. The infected leaves are thus cut using a secateurs, branch of the tree. Tip: If the infected tree is very large, only the affected leaves can be removed. Of great importance in removing the leaves is clean tool. In order to prevent transmission of the infected fungal tissue by the cutting tool, it is advisable to remove it beforehand e.g. to disinfect with the help of alcohol. There are a few things to keep in mind when disposing of the cut: Since the leaves can not only be infected by the other leaves on the tree, but also the dead leaves in the compost, it is advisable to completely remove the cut from the garden.
Against the fungus with broadband fungicides
The first step is the removal of the affected leaves. After the acutely infected parts have been removed, the remaining plant parts can be treated with so-called broadband fungicides. These are unfortunately due to the strength of the fungus, mostly necessary, although biological remedies and home remedies can be used supportive, but often do not come to the heart of the problem.
Biological control and home remedies
The most promising protection against leaf spot disease is the purchase of vigorous plants. Unfortunately, even very resistant plants are not guaranteed protection, so here are some tips for biological control to be given. Preventive works best a large spatial distance between the different plants. Also general care aspects, which influence the condition of the plant, play a role: Few light, a lack of nutrients or the wrong nutrients, or also sunburn and wrong fertilization increase the chances and wrong of the causal mushroom. During the dry season, it is advisable to simply water the soil in susceptible plants. This ensures that the leaves are surrounded by the lowest possible humidity, a living environment that prevents the infestation of leaf spots. Due to the persistence of the fungus, home remedies are unfortunately not proven to be advisable.
Home remedies for strengthening resilience
Instead of chemical fertilizers, it is also possible to strengthen the plants with traditional home remedies:
- Roses can be promoted by not throwing away the coffee grounds of the afternoon coffee, but processing them into the soil.
- Also the cooking water of the breakfast ice cream, 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. Once the hard shell has been crushed with the help of a knife, it can be mixed under the ground, giving new energy to houseplants in particular.
- Somewhat more unusual is the use of horn remnants. Horn rests are, for example, cut fingernails or hair rest.
- Is leaf-spot disease contagious? - Yes, the disease-causing fungus is easily transmitted to neighboring plants via the air and direct contact.
- Is it possible to remove the leaf spots only by biological means? - Infested plants unfortunately can not be "healed" again. However, prevention by biological swelling is very possible.
In the case of leaf spots it is necessary to distinguish between parasitic causes, i. caused by pests (fungi, bacteria, bacte- ria) or that cause non-parasitic damage. About 60 percent of leaf spots are caused by fungus. First signs of infestation usually appear in the form of yellow spots. These enlarge rapidly and tan in the center. It often happens that single leaf spots flow together and then the whole leaf is brown. In heavy infestation, the leaves may curl up and fall off. On the underside of the leaves, the 0.1 mm black fruiting bodies of the fungus can be recognized at the sites of infestation. Important representatives of this group are the fungus genera:
- the real and false powdery mildew fungi,
- as well as rust mushrooms.
- To prevent fungal attack, one should remove the fall foliage, as it forms the spores of the tan fungus, which infect the new leaves in the spring. Therefore you should not compost the leaves in your own garden. The temperature reached in this case is usually not enough to kill the pathogens. Infested fallen leaves should be taken to urban composting or to recycling centers.
- A typical feature of a bacterial leaf spot disease is a transparent appearing patch or patch surrounded by a bright yard. The area is destroyed by bacteria.
- Even flowers can be affected. Bacteria but slimy substances that fill the partitions of the cells. Especially in wet years there is an increase in bacterial infections, as well as in over-head irrigation. Geraniums are often attacked by bacteria.
- Bacterial infections are transmitted by rain, wind or insects. Mostly you have to use chemical substances to combat.
Animal pathogens that can cause leaf spots are, for example, nematodes (roundworms). Leaf nematodes cause angularly defined dark or red spots. Nematodes often transmit viral diseases to plants. In the case of infestation with nematodes, in contrast to the infestation with fungi on the underside of the leaves, no fungal lawn can be seen. The nematodes penetrate through injuries or the stomata in the plant, live in it and feed on the contents of the cells. It is especially in damp years to damage, as they need to travel on the plants a water film.
For the control of leaf nematodes in Germany no funds are currently approved.