For several years now, the once popular boxwood has been suffering from a drastic loss of its good reputation. While the evergreen tree was once considered the perfect choice for low and high hedges, borders and topiaries, in recent years new diseases and pests have been making life difficult for both the box and the gardener. Read when rescue measures are worthwhile.
How can I save a sick boxwood?
To save a boxwood, you should cut it between January and March, dust it with algae lime from April, keep the pH of the soil between 7 and 8 and ensure a balanced supply of water and nutrients. Also plant boxwoods with sufficient spacing and choose resistant varieties.
Boxwood diseases on the rise
The main problems are the stubborn boxwood shoot death caused by the fungus Cylindrocladium buxicola, as well as the boxwood borer, which is very difficult to control and whose caterpillars quickly eat entire stands bare. 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 there are already hundreds of caterpillars on the box, only drastic measures can help. Both diseases have only been known for a few years and were introduced through imports from other parts of the world. Nevertheless, they massively threaten the European boxwood and, associated with it, a centuries-old garden culture.
Appropriate rescue measures
While even gardening experts were at a loss a few years ago, today we know much more about the harmful organisms mentioned - especially 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 as usual between April and September.
- Instead, use the scissors on a frost- and rain-free day between January and March.
- Dust the boxwood with fine algae lime from the beginning of April.
- Algae limescale is also not unproblematic for other reasons.
- But it is a real miracle weapon in the event of an acute or impending infestation.
- Consistently maintain soil pH between 7 and 8.
- Ensure a balanced water and nutrient supply.
As a preventative measure, you should never plant boxwoods too close together, but rather leave a little more space between the individual plants. Also choose less sensitive varieties: The border varieties 'Blauer Heinz' and 'Suffruticosa' in particular are often severely affected, while others (such as 'Faulkner' or 'Herrenhausen') are rare.
When it is better to replace the boxwood
If the infestation occurs before June, even a box tree that is already bare can often be saved. However, things become more difficult when the disease and its drastic effects occur later in the year. The earlier the infestation and control take place, the more time the book has to recover and produce new growth. However, the probability that a bush that is bare or heavily pruned in autumn will recover and sprout again by spring is low.
Tip
Although brown leaves often indicate a fungal disease, sometimes it is just sunburn.