If brownish-black spots of different sizes appear on the leaves of the apple tree and the leaves are shed prematurely, this is often a leaf spot disease. You can find out in this article whether you can prevent this and how it can be treated.
What leaf spot diseases are there on apples?
Spots and discoloration of apple leaves are usually caused byfungiof the genusPhyllosticta. TheMarssonina leaf fall disease, which until a few years ago only occurred in America and Asia,caused by the introduced Diplocarpon ascomycete fungus, is also appearing more and more often in home gardens.
How do I recognize Phyllosticta leaf spots?
On the leaves of the apple appearlight spots with irregular edges,which stand out clearly from the surrounding tissue. Later, dark dots appear in the middle. These are the fruiting of mushrooms.
Since the foliage can no longer carry out good photosynthesis, the tree releases plant hormones and the affected leaves are shed. Moisture promotes the spread of fungal pathogens.
How can I get this leaf spot disease under control?
The spread of Phyllosticta can be effectively prevented and combated byvarious measures:
- Prune the apple trees regularly and ensure that the crown is loose. This means the leaves dry faster.
- Remove fallen and infected leaves and dispose of them in household waste.
- Unfortunately there are currently no home remedies for leaf spot disease.
- Broad-spectrum fungicides from specialist retailers are effective, but should only be used with caution.
How do I recognize Marssonina leaf fall disease?
In summers with a lot of precipitation, grey-black spots appear on thetop of the leaves as early asJune,those of ared-violet Edge are surrounded. The entire leaf turns intense yellow. It is also noticeable that the apple tree is losing a lot of leaves.
The fruits are not affected by this fungus. However, as a result of the premature loss of leaves, the apples remain smaller. Next year you can expect significantly reduced flower and therefore fruit set on an affected tree.
How can I prevent or combat Marssonina fungus?
Since moisture promotes the spread of the fungus, you should ensure aloose crown structurethroughregular pruning. The following measures are also helpful:
- Cut off infected leaves.
- Pick up fallen leaves immediately.
- Dispose of all plant parts in household waste.
Unfortunately, it is usually not possible to combat it with home remedies. Preparations that are effective against scab also work against Marssonina leaf fall disease, but for ecological reasons they should only be used in the home garden in exceptional cases.
Tip
An optimal location prevents leaf spots
In a place where the apple tree is already surrounded by the sun in the morning hours, the foliage covered in dew dries much faster. If you keep the crown structure loose and ensure a good supply of nutrients, the fruit tree can better defend itself against fungal diseases.