These last couple of weeks I’ve been outdoors cutting sprigs of boxwood for use in arrangements, garlands, and wreaths. It’s an evergreen that holds up in holiday adornments both indoors and out. And maybe, like me, you appreciate having the plant in your garden in all seasons. According to a survey of 4,000 landscapers, it’s the most popular garden shrub today.
And what’s not to like? It’s deer-resistant, drought-tolerant, versatile, an evergreen, and easy to grow. It’s been a staple in formal gardens for centuries and an integral landscape plant in my home state of Virginia since the mid-1600s. Sadly, the future of boxwood is now in jeopardy. A fungus, C. buxicola, has resulted in ‘boxwood blight’ that may destroy box the same way that the chestnut blight destroyed trees in the 30s.After taking a toll in European gardens, the blight was detected in 2011 on plants in a North Carolina nursery. It has since been reported in Virginia, Maryland, Rhode Island, Massachusetts, Ohio, Oregon, New Jersey, Pennsylvania, Connecticut, Delaware, New York and British Columbia. Has it reached New Hampshire yet?
Currently, no cure has been found but research is being conducted to combat the disease. Box can be treated with strong fungicides, but as of this date, the fungus cannot be eradicated. English and American Box seem to be the most susceptible. Japanese and Korean boxwood may be less susceptible. Three plants in the boxwood family are affected: boxwood, pachysandra, and sweet box (Sarcococca). Who knew pachysandra was in the box family? Not me. From pachysandra, the pathogen can spread to box.
From property to property, the sticky spores can adhere to animals, garden equipment, clothing, shoes, vehicles…. as well as by wind and rain. The spores remain active for 5 years in plant debris and soil. The spread of box blight on a plant is often rapid and hardly gives the gardener time to react. Here’s how to recognize symptoms: dark circular leaf spots often with darker margins that may eventually grow together and cover the leaf, black streaks or lesions on the stems, and finally, rapid leaf drop.
The boxwood gardens at Woodrow Wilson Presidential Library in Staunton VA (below), installed in the early 1930s by The Garden Club of Virginia, succumbed to the blight and
has been replaced not yet replaced (see update from Dianne in comments). Infected box was bagged and either burned or buried. The Garden Club of Virginia has since prohibited boxwood cuttings to be used in any club event statewide. What to do to prevent the fungus?
Experts say to avoid overhead irrigation, avoid high nitrogen fertilizer, disinfect garden tools, buy from reputable dealers, isolate new plants for 4 weeks, do not work with this family of plants when wet, and space your plants.
Report suspected cases of boxwood blight immediately to your local Extension agent. They can determine whether the disease is blight or similar looking disease.
In the meantime, I am ready to make substitution in my tiny parterre garden in zone 6 if the blight reaches my box. Japanese holly (Ilex crenata) will be my first choice with its similar form, density, leaf size. Other small edging choices for gardeners can be thyme or lavender, compact ornamental grasses or dwarf yew, globe arborvitae or hosta, or for our area, perhaps try a zone 6 hardy rosemary… (Rosmarinus officinalis ‘Madeline Hill’).