Strengthening and protecting box trees
23 Apr 2019
Box tree (buxus) - Photo: BGL
The box tree (buxus) is extremely popular among garden owners. It has been implemented as a topiary plant for centuries. However, at the moment it has developed into a problem case in many places.
The evergreen box tree with its small, oval leaves was already implemented as a hedge in ancient times. Because due to its slow and dense growth, it can be readily kept in shape. One is familiar with it being used as a low perimeter for flower and vegetable beds in old cottage gardens and it is also found as a typical design element in Baroque gardens. In modern gardens one predominantly finds trees that have been artistically styled into balls, cones or spirals.
A new disease and an imported pest have led to huge losses in many gardens over the past years: The so-called box tree shoot dieback is a disease that is caused by a fungus (cylindrocladium buxicola), which causes the plants to lose a lot of leaves and kills the young shoots and quickly makes the shrubs look unsightly. The fungus is transmitted via water and the wind. Furthermore, in some regions the box tree moth (cydalima perspectalis) is also a big problem. The greedy insects originally come from East Asia and were sighted in Germany for the first time in 2006. Over the following years they also spread to Switzerland, the Benelux countries, France, Great Britain, Hungary, Austria and Turkey. It is a moth that predominantly lays its eggs on the outer leaves of the box tree. The caterpillars that hatch are very greedy and can transform an infested evergreen into bare twigs within a few days. In the summer a new generation of moths can evolve every two to three months.
It is thus no surprise that as far as plant protection is currently concerned, the box tree should be at the top of the consumer's list. Correspondingly, many manufacturers have developed entire concepts that aim to strengthen and protect the shrubs.
“Neudomon Buchsbaumzünslerfalle“ (box tree moth trap) - Photo: Neudorff
Recognizing the fact that the plants have been infested by moths at an early stage plays a major role here. However, in the initial stage this is difficult, because the caterpillars are tiny at first and the damage they cause is difficult to discover. Special pheromone traps for moths can be useful here, for example the "Neudomon Buchsbaumzünslerfalle" by Neudorff. These attract male moths using a sexual attractant. They get stuck to the bottom of the trap that is covered in glue and then there is no escape. This has two advantages: On the one hand they can fertilise significantly less females and on the other hand it provides the garden owner with information about the flight period of the moths or when the eggs are laid and he then knows when to expect the next generation of moths.
Ideally the caterpillars of the moths are exterminated while they are still in the initial stages. Insecticides with active agents like azadirachtin, chiacloprid and acetamiprid or also bacillus thuringiensis have proved effective here. When implementing such sprays, today the environmental aspects are also important to most customers. The protection of bees has particularly become a key sales argument. "Raupenfrei Xentari" for instance is a biological compound which is effective against young and older caterpillars of the box tree moth and is nevertheless harmless to the beneficial insects.
Leaf liming - Photo: Hauert
A so-called leaf liming also helps the box tree ward off a pest infestation and fungal diseases. Various manufacturers stock the corresponding products in their line-ups. For instance Schacht's "Algenkalk Pulver" or "QUARDO Algenkalk". The powder forms a microfine coat on the leaves and thus also a physical barrier that protects the plants. As a rule, it comprises to 100 percent of natural fossil marine algae deposits. For the correct application diverse powder sprayers are offered in the retail trade. The devices are normally available with different attachments. This enables the powder to reach the surfaces to be treated readily or also the underside of the leaves.
So that the plants are resistant against diseases and pests, an optimal supply of nutrients is of course decisive. Recently different products have been developed especially for box trees: "Gärtner´s Buchsbaumdünger" for example is suitable as an NPK fertiliser for shrubs planted in the ground or in pots and ensures a constant growth and dense foliage. Thanks to its high share of plant-based ingredients the organic/mineral "QUARDO Buchsbaum-Dünger" has both a good instant and long-term effect and also improves the soil life. The organic fertiliser "Buchsbaum-Fluid" by Schacht excels with valuable secondary plant substances and essential trace elements from olive compost and neem. It is also recommended to use this fluid fertiliser for the leaf fertilisation of the box trees. This enables the nutrients to reach the place they are needed even faster.