|How to control box blight|
If you have common box growing in your garden, either as hedging or topiary then box blight is something you should both be aware of and know how to identify quickly. Why? Because it is an incredibly destructive and fast acting disease which leaves a significant amount of damage in its wake.
Box blight is the common name given to two fungal species - Cylindrocladium buxicola (syn. Calonectria pseudonaviculata) and Pseudonectria buxi. They thrive on topiaried box and formal box hedging as the regular cutting of box pants encourages very dense, compact growth. This restricts air movement and increases humidity within the plant which favours fungal growth.
|Cylindrocladium buxicola spores - http://www.buxuscare.com/|
In wet conditions fungal spores may also be seen on the undersides of infected leaves. White spores indicate an infection of Cylindrocladium buxicola, while pink spores indicate an infection by Pseudonectria buxi.
Cylindrocladium buxicola is the more damaging of the two and can also infects young stems causing black streaks and die-back.
On vigorous specimens it is possible for new growth to regrow but without action the plant will become infected the following year, starting a cycle that will eventually kill the plant.
Both types of fungi require humid, warm conditions to thrive. Pseudonectria buxi enters the plant through open wounds - such as those created when box plants are clipped. Cylindrocladium buxicola is able to infect unwounded plants affecting both woody stems as well as the foliage.
Cultural control of box blight
|Box blight - http://www.thegardendoctors.co.uk/|
Of course this can seriously affect the shape of hedges and topiary and still may not remove all infected plant material or spores. Be aware that the spores can remain viable on fallen leaf litter for at least 6 years! In an serious out break you only option may be to remove and destroy all affected plants.
Reduce the amount of times that box plants are clipped to produce a more open habit as this will help to improve air circulation throughout the plants. Also avoid overhead watering as Cylindrocladium thrives in humid conditions. There isn't mush that you can do about rainfall but whenever watering is required only water at the base.
Chemical control of box blight
|Box blight - http://www.zen-garden.org/|
If you wish to spray yourself using shop bought produces then consider using Scotts Fungus Clear Ultra, Bayer Fungus Fighter and Bayer Fungus Fighter Plus which can be applied when the new growth appears in the spring.
Always go by the application instuctions on the box although there is anecdotal evidence that spraying once a month during the growing season will give effective results. If you are struggling to find these particular products at you local plant retailers then consider using Bayer Garden Multirose Concentrate 2 or Scotts Fungus Clear Ultra. Neither of these fungicides are listed on the packet as being suitable for the control of box blight but they do contain similar active chemicals as the previous products and can still be used to control box blight, although at owner's risk.
For related articles click onto the following links:
HOW TO CONTROL BOX BLIGHT
WHEN DO YOU TRIM BOX HEDGING?