Its leaf color makes the harlequin willow a decorative ornamental tree. Actually quite hardy by nature, there are quite a few threats that plague the sapling. We list the most common pests of harlequin willow and provide tips on how to combat them.
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Only a few plants are spared from aphids and unfortunately the harlequin willow is no exception. Especially in dry periods, these pests like to settle on it. It is not easy to recognize an infestation, because the aphids are often only noticed when the leaves are already curling, because they have been severely damaged by the injuries caused by the aphids’ mouthparts.
In the case of a mild infestation, you can simply wash off the lice with a sharp jet of water. If the infestation is more severe, you should use a soft soap solution.
Instructions for making a soft soap solution:
- 40 g soft soap
- 1 liter of warm water
- dissolve soap
- possibly add a few drops of neem oil
- Let the solution cool down
Spray the cooled solution on the affected areas. Treat the willow generously, as the solution will also wash away the sticky aphid droppings. The excretions clog the leaf openings, which reduces the cellular respiration of the leaves and the leaves can die. For lasting control of lice, you should spray the soft soap solution on repeatedly.
If potted plants suddenly drop their leaves in early spring and entire shoots die off, this indicates an infestation with grubs. These have nested in the pots (they find warmer and better conditions there) and are now eating away at the roots. These are often the voracious larvae of the cockchafer (Melolontha).
Check the roots for damage and cut away damaged roots. Depending on how many roots are left, you may need to trim the willow heavily. The willow is then planted in a fresh substrate.
To prevent future infestations, here are a few things to keep in mind:
- do not use artificial light at night
- Cover soil with insect protection net from May to June
- Pack root balls in a very close-meshed root lattice
- Scarify the area around the pasture regularly
Prolonged drought is ideal for spider mites to proliferate. These pests can be recognized by the fine, irregular webs between the leaves of the harlequin willow. Leaf discoloration or lightening is also part of the damage pattern. If the infestation is severe, the leaves will eventually die off.
Spider mites are very easy to get rid of. Since they prefer dry climates, all you need to do is create a humid environment. Shower the harlequin willow regularly. Spider mites usually disappear within a few days.
willow leaf beetle
The willow leaf beetle (Chrysomela vigintipunctata) often looks like a ladybug at a cursory glance. Compared to ladybirds, this harlequin willow pest has a more elongated body and the spots are irregular and mostly rather elongated. The basic color can be whitish, yellow or reddish.
The beetle is primarily a problem in gardens that are close to larger bodies of water. A larger garden pond is already sufficient to attract the insects.
Also treat the harlequin willow with a solution of soft soap. However, instead of adding neem oil, add a generous splash of spirit. Again spray the willow well on the top and bottom of the leaves.
Hanging or dying leaves on the harlequin willow are also part of the damage caused by the willow borer (Cossus cossus). This pest is a species of moth that specializes in grazing. The butterflies lay their eggs on the willow and the larvae bore into the wood. The caterpillars themselves can be recognized by their orange-red coloration.
A few caterpillars are usually not a threat to the pasture. In order to prevent a stronger infestation, you should avoid artificial light sources at night so that you don’t attract the butterflies in the first place. The willow borers give off an odor reminiscent of vinegar. This is only noticeable when there is a heavy infestation.
Affected branches should be cut out immediately and disposed of in the residual waste. You should also spray the remaining shoots with a quassia broth. Quassia is a wood that you can get in the pharmacy, for example.
Making a Quassia Broth:
- Soak 250g of Quassia wood in 2 liters of water overnight
- Boil for 30 minutes the next day
- Dissolve 500 g soft soap in the broth
Treat the harlequin willow with the cooled broth by spraying it well from all sides. The eggs and small caterpillars that have already hatched die off quickly.
Many people hardly see the willow foam planthopper (Aphrophora salicina) itself. The insects are brown, elongated and very inconspicuous. The larvae are easier to recognize because they are surrounded by a foam structure. The larvae are sucking insects that damage the shoots. Bulges form on the suction scars, which weaken the shoots. In general, affected shoots often only take care of themselves because they can no longer be adequately supplied.
The willow foam cicada usually occurs only sporadically. You can rinse the willow with a strong jet of water, which usually washes off the larvae as well.
Voles are also a common problem in the garden. As a preventive measure, you can already protect the root ball when planting with a vole screen. Fighting voles is usually very expensive. There are different methods that are more or less effective, which is why many gardeners at some point resort to poisoned baits or traps. Regular mowing of the area around the pasture has a disruptive effect on the pests of the harlequin pasture. The voles are chased away by the vibrations of the lawn mower.
frequently asked Questions
As a rule, the pasture is spared from scale insects. In rare cases, scale insects can be transmitted commercially. Therefore, always check the plants before you buy them to see if they have any visible pests.
Basically, it is always a good idea to offer beneficial insects a habitat in your own garden. In the fight against harmful insects in the harlequin willow, birds and ladybugs are two particularly important helpers. They keep most of the pests in check.