Hostas are the stars in shady locations in the garden. There, however, they are threatened by predators that cause holes in the leaves. In addition, some varieties are very sensitive if the location is not suitable. The result can be yellowish discoloration, which also occurs when the plants are damaged by diseases. The leaf problems on hostas can be prevented with a little care and some preventive measures.
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Discoloration or winter winter preparation
You should clarify in advance whether the discoloration is caused by leaf problems on hostas or just natural processes. There are some varieties whose characteristics include yellow leaves. If problems occur, the leaves usually become lighter yellow, but this can usually only be seen on closer inspection. At the latest when leaves die off during the season, you should take a closer look at the plants.
Once a year – in the fall – it is normal for the hosta foliage to turn yellow. This has natural causes and is necessary so that she can prepare for the winter. The plant then gathers its strength in the roots and simply lets above-ground parts die off that would not survive the winter.
snails
The main enemy of the Hosta are the snails. Due to the fact that both snails and plants prefer shady and damp locations, they are a favorite food for the animals. Especially in very dry periods, it can happen that not only are there holes in the hostas, but the plants are completely bare within a few days.
Snails and garden are a perennial problem with little natural means to combat these predators. If you have the opportunity to plant the Hosta in pots, attach a sleeve against snails to the pot. There are now such barriers for pots on the market.
A slug fence can also help outdoors, but many gardeners use organic slug pellets there. Many measures, such as spreading sawdust, are ineffective there because the moisture means that these barriers are no longer unpleasant for snails and they crawl over them.
Dickmaulrüssler (Otiorhynchus)
The vine weevil is also a feared pest in the garden because it is not particularly picky. It prefers soil rich in humus, in which hostas also thrive. Both the beetles, which are 7 – 12 cm long and vary in color from dark brown to black depending on the species, and the larvae cause great damage.
The damage caused by the beetle is easy to recognize because, unlike snails, they eat the leaf edges in a semicircular manner. The beetles themselves are easier to control compared to the larvae. To do this, proceed as follows:
- Fill clay pots with wood shavings
- Set up pots upside down in the area of the infested hostas
- Collect pots daily
- Remove beetles with wood shavings
- Refill and set up pots
Collect the beetles and at the same time prevent them from multiplying, because the larvae cause far greater damage. They eat away at the roots, which in turn causes the leaves to turn yellow and even the entire plant to die. If the leaves are yellow and there are additional signs of eating, you should definitely dig up the plants and check the roots.
If larvae are found there that look similar to grubs, you should dig up the plants immediately as an emergency measure. Shake off all of the soil to make sure there aren’t any larvae left behind and replant in a different location. As an interim solution, you can put the hostas in a pot and put them in the shade. After the hostas are removed, treat the area liberally with nematodes.
Note: You should wait at least until next year before replanting a hosta in the same location.
Wühlmaus (Arvicolinae)
Voles are real gourmets in the garden, and hosta is also on their menu. If the voracious animals attack the plants, this manifests itself at an early stage in the form of leaf problems on the hostas. The leaves wilt and discolour, eventually dying off altogether as the roots have been eaten by the voles for nourishment.
There are three proven ways to protect hostas:
- catch voles
- Repel voles with scents
- Make grazing protection around the roots
Products from specialist retailers have proven their worth when it comes to using fragrances to drive them away. Home remedies such as nut or elder leaves have little or no effect.
Hosta-Virus X
It has been known since around the year 2000 that plants that are cultivars with striped or mottled leaves that also had bumps in the affected areas are affected by a problematic disease. This is the so-called Hosta virus X, HVX for short, which has become a major problem for Hosta friends in recent years.
The virus gets into the garden via purchased plants that are already infected. In nurseries or perennial growers, the virus finds a good breeding ground due to the abundance of plants. However, it can take between two and seven years for the virus to break out. This, in turn, is a problem when buying a plant, since the plant may be infected at the time, but not yet showing any symptoms. Symptoms include:
- bleeding (cell discoloration starting from the leaf veins)
- sunken cell tissue (dents)
- light green to yellowish speckled leaves
The virus is transmitted via the plant sap, for example through injuries when dividing the clumps. Once a plant is affected, it can only be disposed of. So far there are no measures to combat the virus. To prevent infection, dispose of infested plants with household waste. Garden tools and clothing should be cleaned thoroughly afterwards.
To prevent transmission of the virus in the garden, when working on different perennials, the tool should be cleaned before moving on to the next plant. It is less of a problem if you only have one plant in the garden and only these parts.
Tomato ring spot virus
The tomato ring spot virus is easy to distinguish from HVX, because the majority of it does not start from the leaf veins, but forms spots between the leaf veins. The spots are yellow, but not associated with arching of the leaves.
Compared to HVX, tomato ringspot virus is less dangerous. If the infestation is low, all you have to do is remove the leaves. However, if the entire plant is affected, you must discard it. The tomato ring spot virus can not only infect the hosta, but also vegetables such as tomatoes or cucumbers.
Chlorose
The chlorosis causes clearly visible leaf problems on hostas, but can usually be remedied without further damage to the plants. In this case, the leaves turn distinctly yellow, only the leaf veins remain green. Chlorosis can have several causes:
- too much lime
- compacted soil
- waterlogging
- immature compost
If these causes are eliminated, the leaf problems will quickly disappear and the hostas will develop well again.
nutrient deficiency
Chlorosis and nutrient deficiencies are usually difficult to detect at an early stage as they both have yellowish discoloration between the leaf veins. With a nutrient deficiency, however, the discoloration is not as strong as with chlorosis. If there is a lack of nutrients, a liquid fertilizer for perennials is a quick help. If you have nettle manure in your garden, you can use it instead of commercially available fertilizer.
You can prevent nutrient deficiencies by treating the plants with a slow-release fertilizer in the spring. The following fertilizers are suitable for this:
- Hornspäne
- mature compost
- mature horse or cow manure
