Hartley Magazine

All the latest news, hints, tips and advice from our experts

Plenty of options for gardeners fighting box blight

Box is a very popular form of topiary that is often used as an alternative to hedgerows. It can line borders beautifully and is noted for it very distinctive scent, which is beloved by many gardening professionals and green-fingered enthusiasts alike.

Its Latin binomial name is Buxus sempervirens – and it is an evergreen shrub or small tree that can grow to anywhere from three feet, three inches to 29 feet six inches in height. It also has plenty of very small green to yellow-green, oval leaves.

However, maintaining the plant is not without certain difficulties – particularly if is is struck down with box blight. This is a kind of fungal disease that causes some of the plant to die, creating many unsightly bare patches. When the plant is arranged in topiary and parterres, this is a particularly difficult problem to address.

Two different forms of fungi – Cylindrocladium buxicola and Volutella buxi – are behind this. While they are separate strains of fungi, they are very often found together – and the disease is exclusive to Buxus sempervirens, having not been found in any other plants to the present day.

It is easily identifiable, as the spore masses of the fungi are clearly visible on the infected leaves in wet or even damp conditions, showing up white and pink.

Bunny Guinness – who is a chartered landscape architect, a regular panellist on the BBC Radio 4 show Gardeners' Question Time and author of the Family Gardens book – urged those who think their box may have been infected to ensure they get it checked before committing to treating it.

In an article for UK national newspaper the Daily Telegraph, she said that if it is confirmed, then all particularly badly infected plants should be removed from the garden entirely.

One possible method of treatment is to quarantine infected plants for three weeks – although Ms Guinness advised against overhead irrigation or applying fertiliser, as this can encourage vulnerable growth.

"Cutting box encourages very dense growth," the expert remarked, adding: "Air movement is restricted and fungal growth is favoured in this close environment. If you can open out the dense inside framework, a process often called 'halting clipping', it helps."

"Remember, though, that cutting plants when it is wet is bad news – it spreads the spores. So cut when you have six or seven dry days ahead. If you are going back and infilling with box, then it is worth tracking down more resistant varieties."