For several years, the once popular boxwood has suffered from a drastic loss of its good reputation. The evergreen tree was once considered the perfect choice for low and high hedges, edging and topiary, but in recent years new diseases and pests have been making life difficult for both box and gardeners. Read when rescue measures are worthwhile.
A box tree can only be saved if action is taken in good time
Boxwood diseases on the rise
The main problems are the stubborn boxwood shoot dieback caused by the fungus Cylindrocladium buxicola, as well as the boxwood moth, which is very difficult to control and whose caterpillars eat entire stands bare within a very short time. The latter is particularly treacherous because the infestation is often noticed too late. The caterpillars begin their feeding activity inside the bush and slowly work their way outwards from there. If hundreds of caterpillars are already cavorting on the Buchs, only drastic measures will help. Both diseases have only been known for a few years, they were brought in by imports from other parts of the world. Nevertheless, they are a massive threat to the European boxwood and the centuries-old garden culture associated with it.
Appropriate rescue measures
A few years ago, even gardening experts were at a loss, but today we know a lot more about the harmful organisms mentioned - above all about how an infestation can be combated or even prevented. For both diseases, it is best to use these remedies:
- Do not prune the box between April and September as usual.
- Instead, grab a pair of scissors on a frost-free and rain-free day between January and March.
- Dust the box with fine algae lime from the beginning of April.
- Algae lime is also not unproblematic for other reasons.
- But it is a real miracle weapon in the event of an acute or impending infestation.
- Consistently keep the soil pH between 7 and 8.
- Ensure a balanced water and nutrient supply.
As a preventative measure, you should never plant box trees too densely, but rather leave a little more space between the individual plants. Also choose less sensitive varieties: the edging varieties 'Blauer Heinz' and 'Suffruticosa' in particular are often severely affected, while others (such as 'Faulkner' or 'Herrenhausen') are rare.
When is it better to replace the boxwood
If the infestation occurs before June, even a bare box tree can often be saved. On the other hand, it becomes difficult if the disease and its drastic effects appear later in the year. The earlier infestation and control take place, the more time the box has to recover and sprout again. However, the probability that a bush that is bare or severely cut back in autumn will recover and sprout again by spring is low.
tips
Although brown leaves often indicate a fungal disease, sometimes it is just a sunburn behind it.