What is Box Blight?

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What is Box Blight?

Box is an extremely popular plant for creating hedging and topiary. With regular tight clipping, it can retain an almost perfect formality year after year, and it can be tailored to suit the style of your garden, whether classic or modern.

Unfortunately, Box is also susceptible to a number of pests and diseases, including Phytophthora root rot, a fungus called Box rust and pests such as the Box sucker, Box tree caterpillar Box leaf-mining gall midge, Mussel scale and Box red spider mite. And of course, the dreaded Box Blight.

Causes by two fungi, Cylindrocladium buxicola and Volutella buxi, Box Blight is an airborne fungal disease that attacks Box or Boxwood leaves and stems, which are plants of the genus, Buxus. If left untreated it can result in dieback and bare patches and can quickly spread to other Box plants nearby.

First reported in the UK in the mid 1990s and seen as a widespread problem across Europe by 1998, it is suspected that Box Blight originated in central America, although this theory has not been proved.

How does Box Blight spread?

Box Blight is an airborne fungus; therefore the spread of spores are primarily through water droplets carried by the wind. However, because the spores are sticky, it is possible for Box Blight to be spread by birds, insects, people and in particular, garden tools.

Once spread, resting spores are produced, which can survive drought, are unaffected by frost and remain viable for extended periods of time. For example, spores are produced in the spring yet viable spores can still be found in decomposing leaves after almost a year.

The Box Blight fungus penetrates the leaf via the stomata, meaning that cuts or wounds in the leaf are not needed for germination to occur. Rapid germination can occur as soon as five hours after penetration, depending on conditions.

How to identify Box Blight

It is very easy to miss the early stages of Box Blight; often the disease will not be detected until parts of the Box plant dies and you notice significant leaf fall in your garden.

However, there are a few symptoms to look out for. Early infection results in a general darkening of the leaves, which spreads until whole leaf is discoloured. By this time the fungus will have spread to the stem, resulting in dark lesions in the stem and the death of the leaf.

Spore masses may also be seen on the undersides of the infected leaves in wet conditions, with pink indicating Volutella buxi and white denoting Cylindrocladium buxicola.

How can Box Blight be prevented?

As a widespread, airborne fungal disease, there are no specific Box Blight fungicides on the market that have been proven to be effective. However, there are measures you can take to reduce the possibility of serious infection in your garden:

  • When buying Box plants from a garden centre or other commercial source, keep them in isolation for a minimum of three weeks before planting to ensure that any suppressed disease is discovered before it can affect existing, mature plants.
  • Avoid planting Box in damp, shaded, poorly ventilated areas as these are conditions Box Blight thrives in. Avoid overhead irrigation at all costs as spores are most commonly spread in water droplets.
  • Regularly clean your garden tools, in particular your clippers and shears to avoid the transfer of spores. You can dip tools in diluted household disinfectants or bleach.
  • Remove any dead leaves and foliage to minimise the chances of resting spores releasing the infection.
  • If disease does break out, remove and destroy the infected plants.
  • Is it absolutely essential that you have Box plants in your garden? Other hedges and topiary plants can be equally as effective and don’t carry the risk of Box Blight. These include various Berberis plants and Euonymus fortunei cultivars, as well as Lonicera nitida and Rosmarinus officinalis.

If you are worried or need advice regarding Box Blight then please contact us here at Stock Gardens. We offer a FREE consultation to any of our customers and any referrals from them. 

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