As robust as the boxwood may seem, it is usually not spared from pests. We show how to recognize the symptoms and fight the pests.
When you think of the box tree (Buxus), the box tree moth usually comes to mind first when it comes to pests. Unfortunately, he's not the only one who likes to attack our book. We present the various pests and show how to fight them successfully.
Not only diseases affect the boxwood, but also pests can attack it. Small animals eat their fill of our plants and usually leave a sad picture behind. Below we explain what you can do and who you are actually dealing with.
Box tree moth
One reason for box trees being eaten away is often the caterpillars of the box tree moth (Cydalima perspectalis), which originally comes from East Asia. In this special article on the box tree moth, we will tell you how you can identify this pest with certainty.
Box tree moth: symptoms
The voracious caterpillars can be found on boxwood bushes from mid-March. The butterflies, on the other hand, are rather inconspicuous with their white wings with brown tips, but their offspring are only too happy to attack our boxwood. The green caterpillars, which are up to 5 cm long, have eye-catching black dots and a black head capsule. First they eat windows in the box leaves and over time the caterpillars eat all the leaves and even shoots. Since they start from the inside of the bush, the infestation is not initially noticeable. The caterpillars later become entangled and your beloved boxwood is finally covered in a spiderweb-like web.
Tip: Pheromone traps such as the Plantura borer trap are used for early detection of a borer infestation. In this way, you can quickly take active action against the malware.
Fight box tree moths
If you take a close look at your boxwood regularly and also take a look inside the bush, you will hopefully recognize the infestation early on, because then there is oneCombat still possible without any problems. A biological spray such as our Plantura Zünslerfrei XenTari® is ideal for this. There have also been sightings of native birds eating the bitter caterpillars, but this is usually not enough.
In addition to biological sprays, you can also try collecting the caterpillars by hand or spraying them with a jet of water, but always use gloves to be on the safe side, as the caterpillars absorb toxins from the boxwood. The extent to which these toxins are released by caterpillars is not yet known. Therefore, you should exercise caution when disposing of the box tree moth larvae. You can also read more about successfully combating the box tree moth here.
Top mite on boxwood
Twisted shoots and leaves are caused by the shoot tip mite (Eriophyes canestrinii), which belongs to the gall mite family. In contrast to other gall mites, this one does not cause galls and growths, but rather deformities.
Tip mites: Symptoms
The shoot tip mites cause deformation of the boxwood shoots by sucking sap out of the plant cells. This stuns the leaves and shoots of the boxwood, leaving the leaves small, thin, and growing twisted.
Control of shoot tip mites
The shoot tip mites do not pose a serious threat to the box, but are more of an optical problem. If you trim your plant regularly, you shouldn't have much of a problem with these mites. If you find individual shoots with the shoot tip mites, you can remove them as well.
'Green Mountain' is a boxwood variety that is particularly susceptible to these gall mites, but there are also varieties that are less sensitive to these mites - these include 'Herrenhausen', 'Faulkner', 'Hollandia' or 'Handsworthiensis '.
Spider mites on boxwood
Since 2000, a relatively new pest that originally comes from North America has been detected on box trees in Germany: the box tree spider mite (Eurytetranychus buxi).
Spider mites: Symptoms
You can just about spot these little spider mites on the leaves with your eyes, because they areonly 0.35 to 0.48 mm in size. The boxwood spider mite can reproduce extremely quickly and form up to eight generations per year. The damage caused by these spider mites can be recognized by bright dots and short lines that look like a comma. This damage is caused by the animals sucking on the plant cells. If the infestation is very severe, the entire leaves will turn light and in the worst case the box tree will drop them completely. The mites can multiply best on box trees when they are in sunny and warm locations - but they also occur in shady places, where they only multiply more slowly.
Control of spider mites
These mites are eaten by beneficial insects such as lacewings (Chrysopidae) or ladybirds (Coccinellidaei) and are also washed off the leaves by summer thunderstorms and thus clearly decimated. However, if they are threatened with a severe infestation, you can use oil-based sprays in autumn or spring against the hibernating spider mite eggs. Unfortunately, no particular variety differences with regard to this pest could be found in the box varieties.
Box flea on box
Another sucking pest that can affect boxwood is the boxwood leaf flea (Psylla buxi). The larvae and adults are greenish in color and the larvae form a white waxy wool under which they hide.
Buxus leaf flea: Symptoms
But how does the flea infestation show up on boxwood? The fleas suck on the leaves, excrete sticky honeydew and black sooty mold fungi then settle on it. In addition, the larvae form their white waxy wool coat and thus protect themselves from enemies and from drying out. Fleas sucking on the leaves cause them to become spoon-shaped. The leaf spacing remains rather short and the shoot tips then resemble small heads of cabbage.
Fighting boxwood leaf fleas
The leaf flea usually doesn't bother the box tree much and is also eaten by beneficial insects such as spiders, parasitic wasps or lacewings. Removing infested shoot tips is helpful in combating this. However, striking differences between the varieties were found, because 'Blauer Heinz', 'Elegantissima', 'Angustifolia' and 'Herrenhausen' showed relatively few symptoms, whereasthe varieties 'Pyramidalis', 'Green Mound' or 'Graham Blandy' were very strong.
scale insects on boxwood
Especially with ornamental trees, scale insects or mealybugs are often encountered. With boxwood, one is often confronted with the scale insect (Lepidosaphes ulmi), which also occurs on fruit trees or rose bushes.
Scab bugs: Symptoms
The comma scale insect is about 2 to 3 mm long and grey-brown in colour. In contrast to other scale insect species, this species forms neither honeydew nor sooty mold, but the sucking activities of the comma aphids impair the growth of the boxwood. In the case of a very severe infestation, it loses its leaves and entire shoots can also die off. Due to the shedding of the leaves, these symptoms are easily confused with those of box tree leaf fall, but here you can easily see the lice on the shoots.
Fight scale insects
Because the lice cannot spread very quickly on the boxwood, often only individual branches are affected. These can easily be removed by cutting back. However, if the infestation is very large and cutting back is no longer effective, you can treat the plant with oily spray sprays shortly after the lice hatch in May or June. Be careful not to act too late, however, as once the lice's shields harden, they are not very susceptible to treatment.
Buxus gall midge on box
Particularly in Central Europe (southern Germany and Austria) you have to fight again and again with the boxwood gall midge (Monarthropalpus flavus) and this small insect can cause a lot of damage.
Boxwood midge: Symptoms
About 30 eggs are laid directly into the leaves per female that dies after laying eggs. Small larvae then develop from these eggs, which eat tunnels in the boxwood leaves. These burrows, also known as mines, are easy to miss early in the infestation as they only appear as bright spots on the leaves. Later in the summer, the tissue then thickens and light brown spots appear on the upper side of the leaf, which are not very clearly demarcated from the he althy tissue. Galls form on the underside of the leaf, in which the orange larvae are then located, and leaf shedding can also occur. Exactly these galls with the larvae in them are a good distinguishing feature to the fungus of theBoxwood leaf falls.
Fight boxwood midge
Normally, the gall midges tend to infest older plants and this usually does not cause much damage. However, pruning measures can reduce the infestation pressure and, in the case of a very severe infestation, you can fight the larvae after hatching with insecticides such as Calipso. Here, too, a difference can be seen in the different varieties, since 'Handsworthiensis', 'Angustifolia', 'Herrenhausen', 'Faulkner', 'Rotundifolia' and 'Suffruticosa' are less plagued by the boxwood gall midge. The 'Green Mound' variety from Canada, on the other hand, is particularly badly attacked by this gall midge.
Important boxwood pests in brief
- Box tree moth (Cydalima perspectalis)
- Tip mite (Eriophyes canestrinii)
- Boxwood spider mite (Eurytetranychus buxi)
- Boxwood Flea (Psylla buxi)
- Scales (Lepidosaphes ulmi)
- Boxwood midge (Monarthropalpus flavus)
Buxus damage: frost damage, sunburn and Co.
But not only pests and pathogens can affect your beloved evergreen boxwood. Environmental conditions can also be responsible for damage and the loss of lush greenery. These are so-called abiotic causes of damage, since they are not caused by living organisms. The following abiotic damage can occur on boxwood:
- Freezing and Frost Damage to Foliage and Roots
- Frost drying
- Snowfall
- Sunburn
- S alt Damage
In our special article you can find out how you can recognize such boxwood damage caused by environmental influences and how to distinguish it from pests and what you should do to limit the damage.
Here we will show you everything you should know about boxwood diseases and how to fight them.