Fungi love moisture, which is why a humid summer causes a particularly high number of fungal-related diseases. In most cases you can hardly see anything of the cause; only the symptoms on the leaves and fruits are visible. However, there are also wood-destroying tree fungi with distinctive fruiting bodies.
How do I recognize and treat fungal infestation on fruit trees?
Fungal infestation of fruit trees manifests itself in symptoms such as powdery mildew, sooty mold, verticillium wilt, red pustule disease and Monilia fruit rot. Prevention and treatment include removing infected plant parts, generous pruning, disinfecting tools and choosing a sunny, airy location.
What you can do against fungal diseases on fruit trees
There are no effective fungicides approved for hobby gardening against many fungal diseases. The pathogens must therefore be kept in check through targeted prevention and careful care. These include, for example, these measures:
- early removal of infected plant parts
- generous pruning down to he althy wood
- Disposal of cut plant parts, for example with household waste or by burning
- Disinfecting pruning tools and gardening equipment
Maintaining the correct planting distance is particularly important in preventing such a disease. Fruit trees in semi-shady or shady locations are more sensitive to the pathogens, which is another reason why the trees belong in an airy, sunny location.
The most common fungi on fruit trees
Harmful fungi on fruit often only affect related species or, for example, only pome or berry fruit. There are only a few generalists such as Monilia fruit rot.
Powdery mildew
Probably every gardener knows the white, wipeable leaf coatings of powdery mildew, which occur on fruit and ornamental trees as well as on vegetables, flowers and perennials. However, these are different harmful fungi that cause very similar damage. The powdery mildew fungi differ from other harmful fungi in one important way: they do not need moist leaves to germinate their spores, but appear mainly in warm, sunny summers.
Sootdew
These fungi feed on the sugary honeydew that plant-sucking insects such as aphids and whiteflies excrete. They settle on the stuck parts of the plant and form the typical black deposits. Sooty mold fungi do not damage the plant directly, but can severely impair the photosynthesis of the leaves due to the dark coating.
Verticillium wilt
Verticillium fungi penetrate the plants from the ground through injuries to the roots or root collar and clog the ducts. Typical symptoms are often sudden wilting on individual shoots or parts of branches, with the leaves hanging pale green and limp. As the process progresses, the entire plant can die.
Red pustule disease
The pathogen can infect a number of deciduous trees, but especially plums, cherries, apricots and all types of pome and nut fruits. Red pustule disease primarily affects dead parts of living fruit trees, such as branches frozen back by frost. From here it attacks he althy areas as long as it finds wounds and branch stubs to penetrate.
Monilia fruit rot
Monilia fruit rot is mainly caused by the fungus Monilia fructigena and affects almost all tree fruit species. The pathogen overwinters on dried fruit mummies on the tree, diseased fallen fruit and infected branches. That's why it's so important to remove these parts regularly.
Tip
Tree fungi or tree sponges are also dangerous for fruit trees: common species such as honey fungus, tinder fungus, fire sponge and sulfur fungus penetrate into branches and trunks through wounds and gradually decompose the wood inside.