Box, or Buxus sempervirens, has appeared in gardens since Roman times. With its shiny leaves and distinctive smell, it is often used for low hedges, parterres, curls and formal patterns. Easily clipped, it can stand sentinel at your front door in the form of globes, obelisks, peacocks – even, for the fanciful, mini-elephants.

Box hedging looks best when it makes a strong effect: when it is 18in high and 12in broad, say. Where a hedge turns a corner, you can introduce an obelisk or ball in a B sempervirens variety – ‘Marginata’, with yellow-edged leaves, or ‘Elegantissima’, with white-edged leaves – for contrast. Or grow low mounds of slightly different textures and shades of green. Let them run together, “cloud-pruned” into informal hillocks, and they will look wonderful.

Amid all this greenery, however, a danger lurks: box blight. First found in Britain in a Hampshire nursery in 1994, this fungal disease is spreading. The National Trust had to remove all the box at Buckland Abbey, in Devon (once the home of Francis Drake), and replant with Japanese, or box-leaf, holly, Ilex crenata. At Ickworth House, in Suffolk, which holds the national collection of box, they have dug out a whole perimeter hedge. The National Trust for Scotland has also had problems, and the box is gone at Geilston House, in Dunbartonshire, and at the Charles Rennie Mackintosh-designed Hill House, in Helensburgh, Argyll and Bute.

Private gardens have been affected, too, including that at Highgrove, the Prince of Wales’s Gloucestershire home. At the Laskett, Sir Roy Strong’s garden in Herefordshire, whole sections that depended on box for their structure have been destroyed. The spores can survive in the soil for years, so Strong has completely replaced it in parts.

In some ways, our taste for tightly planted hedges has helped the disease. It is most easily spread (over shortish distances) by water droplets. The spores are sticky, so insects, birds, people and, especially, garden shears can carry them. Closely spaced plants in nurseries, frequently watered and trimmed, give the fungus the perfect breeding ground.

Take action:The first thing to do if you suspect box blight is act fast. The disease has a nasty habit of seeming as if it has abated – with browned branches turning green again – only for it to return later. Do, however, check that this isn’t due to drought or poor soil before you do anything drastic.

Should you find infected branches, prune them out, burning cuttings and debris. If possible, don’t prune adjacent plants for a season or two, to keep them strong. No chemical cure is available, although penconazole (found in garden centres as Scotts Fungus Clear) may help to guard against it. Prevention: Strong has found that some of the gold-variegated varieties are less susceptible; he also hopes that Buxus microphylla‘Faulkner’ might prove immune. Otherwise, he suggests frequently sterilising your hedge trimmers – a blowtorch run quickly along the blades should incinerate any spores.

If your garden is free of the disease, propagate your own new plants to ensure you are not introducing it from elsewhere. Now is a good time to collect as many 4in shoots as you need. Sharp secateurs make the harvest easy: strip the leaves from the lower half of each shoot, then plant where you want them to grow. Space them 3in apart and, if they all root, thin them out to 6in, though they won’t fuss too much if you forget. Leave for three or four seasons before pruning. You can plant them in situ, but it is worth having a few spares in a nursery bed for the occasional replacement.

A faster alternative is to make slits across a tomato grow bag every 4in. Plant cuttings into the compost every inch along the slits, then put the whole thing somewhere shady under glass. Pot up or plant out the new plants the next season. Almost all will root.

If you have to buy in new plants, and already have lots of unaffected box, put the new ones in quarantine for at least a season, well away from healthy plants. Never use the same pruning equipment to trim both.

ALTERNATIVES

You can spare yourself the worry that blight might wreck your garden with one of the following options: For low hedges: Follow the National Trust’s example and use the disease-free Ilex crenata, or “box holly”, from Japan. It looks similar to box, but is not so tolerant of drought.

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