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Summer is hard to imagine without these bright red fruits, and strawberries are also eaten in abundance in yoghurt, jam and ice cream at other times of the year. However, they taste best fresh from your own garden, straight from the bush into your mouth. These are mostly cultivars of the garden strawberry (bot. Fragaria x ananassa) cultivated in Brittany in the 18th century. But what to do if the strawberry plants suffer from diseases?
causes
Why is my strawberry getting red or brown leaves?
If the leaves on your strawberry are turning red or brown, it is usually one of two fairly common ones fungal diseases behind. They are caused by different pathogens, which are independent of each other, but often occur together.
The fungus Mycosphaerella fragariae triggers the vitiligo and the pathogen Diploccarpon earliana (also called Gnomonia comas) leads to red spot disease.
fungal disease
First signs of a fungal disease:
- reddish spots a few millimeters in size on the strawberry leaves
- yellow discolored leaf areas
- usually occurs in humid weather
How can I distinguish these fungal diseases?
Both the white spot and the red spot disease show up as more or less red spots on the leaves, which slowly turn orange, brownish or black in the case of the red spot disease, while in the case of the white spot disease, on the other hand, they form a mostly circular bright center in which the leaf tissue slowly dies . However, since both infections are treated in the same way, an accurate diagnosis is not that important. In addition, mixed infections with both pathogens are not uncommon.
Red and white spot disease on strawberries
treatment
How do I treat these fungal diseases?
In general, it is only recommended to cut off and dispose of the infested leaves, which is quite sufficient for a low infestation. However, do not simply throw the strawberry leaves on the compost, because fungal spores can hibernate there and may later end up on your strawberry bed again. Disposal with organic or household waste is definitely safer. If there is a heavy infestation in autumn, you can simply mow the entire strawberry bed with the lawn mower and dispose of the leaves.
Other diseases & pests
Are there other reasons for discolored foliage?
Not only the white spot or red spot disease can cause brown spots on the leaves of your strawberries, the following diseases and pests also lead to the corresponding leaf discoloration:
- Otiorrhynchus sulcatus (Roughed Vine Weevil)
- Phytophthora cactorum (rhizome rot)
- Steneotarsonemus pallidus fragriae (strawberry mite)
Ridged Vine Weevil - Otiorrhynchus sulcatus
The ridged weevil is a non-flying beetle. It usually hatches in July (early July to early August) and eats the leaves of your strawberries. At the beginning of the infestation, you may only notice the bumpy feeding marks on the leaf edges. Later, usually not until the following spring, the foliage becomes wilted and brown, especially in dry weather. This is due to the larvae of the vine weevil eating the roots. In the event of a severe infestation, the plant can hardly be saved.
Rhizome rot - Phytophtora cactorum
If the rhizome rot occurs, then it first shows up in the heart leaves of the strawberries turning brown. Later, the remaining foliage withers and the plant dies. Sometimes this happens very quickly. In the early stages, the roots are still without any visible symptoms, but as the disease progresses you will see brown to reddish-brown discoloration on the rhizomes. These rotten spots are usually sharply delimited. The root rot pathogen feels particularly comfortable on wet soil and at temperatures of around 25 °C.
Strawberry mite - Steneotarsonemus pallidus fragariae
An infestation with strawberry mites can also lead to severe harvest losses. The plants do not thrive, they stay small and their leaves stun. The foliage turns brown-red to gray before the strawberry dies. A particularly large number of mites appear when the humidity is high and the temperature is warm at the same time. It is usually spread by infected young plants. Later, the mites migrate to neighboring plants and foothills that are densely packed.
prevent diseases
How can I prevent diseases on my strawberry plants?
So that your strawberry plants do not get sick in the first place, you should keep an eye on a few factors and take appropriate precautions.
Risk factors for strawberry diseases:
- planting distance
- moisture from above and below
- bed care
- selection of plants
As a preventive measure, you should not place your new strawberry plants too close together so that any affected plants cannot easily infect each other. A place that receives sun for several hours a day is ideal, so the plants can dry quickly after a downpour.
Do not water your strawberries from above and use a layer of straw to keep the soil surface dry. If fungal diseases occur more frequently in your strawberry plants, then think about a one- to two-year break and then plant older and more robust varieties.
Since the spores of these fungi like to overwinter in infested leaves, these should not remain on the bed but should always be cleared. It is best to clean your bed every fall, even if no infection was visible. So you can be sure that no fungal spores remain there. The pathogens are not only transmitted through direct contact but also through rain and wind. If you want to renew your strawberry bed after a few years, then place the new bed in a different place or fill in fresh, unpolluted soil.
