Welcome to our final Post on preventing Box Blight…
• Keep trimming to an absolute minimum as clipping Box hard encourages extremely dense growth which will restrict air circulation – Box Blight thrives in a closely packed, dense environment.
• Box is not a fast grower, so if keeping the plant’s shape is important, then spread the task over several weeks rather than one Sunday afternoon
• But – do thin out the inside growth to help air flow – this is known as halting clipping. One commercial Box grower recommends thinning in winter by randomly removing sufficient 10-15cm long branches to give the air room to circulate
• The traditional maxim of not getting out the clippers before Derby Day (first week of June) is sound as the danger of frost will have passed
• Never trim or cut when it is particularly humid or the forecast suggests rain over the next six-seven days
• Remove (and ideally burn) all trimmed wood and foliage – even on healthy plants. NEVER add ANY Box to the compost heap or bin
• Keep the soil surroundings any Box (including if it’s in a container) free of weeds and leaf debris – especially any leaves that have dropped from the plant itself
• Clean – really clean – any tools used on your Box. Disinfectant is not effective but household bleach or methylated spirits are (obviously, you can’t use these on a diseased Box). Make sure you then rinse your tools THOROUGHLY to remove any trace of the liquids. When dry you can then spray with a fungicide as this MAY help
• Keep new Box plants well away from established plants for six weeks before planting them to check that they have not brought the disease with them.
Some recommend a quarantine period of up to a year – this is excessive and unnecessary as the plant could easily contract Box Blight during so long a period. Remember, the point of quarantining is to ensure the new plant isn’t already carrying Box Blight.
Indeed, many suggest quarantining the new plants in a moist, shaded and damp spot favoured by Box Blight so any inherent infection will manifest itself more rapidly – in perfect conditions and if the disease is present, it will (re)establish itself within 48 hours.
• Do not replant Box into soil that has had a contaminated plant in it – Box Blight can stay viable in the soil for years
• Check with visiting friends and family whether or not they have Box in their garden before you let them near those in yours. They won’t be offended!
• Only buy from reputable growers and nurseries. Unknown sellers on e-commerce sites are best avoided
And, above all, BE VIGILANT. As for any disease, the best defence against Box Blight is to spot it and remove it the moment it appears. To suggest that Monty Don could have saved his Box may be heresy, but the truth is that by the time viewers of Gardener’s World saw him rip up his beloved low Box hedging, the disease was long-established.