You might have noticed that boxwood plants around your home and garden aren’t looking as healthy as they did last year. The reason could be “winter burn.” West Virginia University experts offer advice to help restore boxwood plants to their previous state and prevent future damage.
“Boxwood plants aren’t native to West Virginia, and they sometimes aren’t as winter hardy as other more common, evergreen plants,” explained Mahfuz Rahman, WVU Extension Service plant pathology specialist.
This winter caused widespread winter burn damage to boxwood plants across the region. Winter burn occurs when plants lose water from their leaves, and roots are deprived of water because the ground is frozen.
“It’s important to take proper measures during the winter months to protect boxwood plants,” Rahman said. “Prune away any damaged parts of the plant in the springtime before new growth starts to help the plant recover from any winter burn from the previous season.”
There are a few ways to determine if boxwood plants have suffered from winter burn. Black or brown discoloration, or bleaching of new growth are typical signs of winter burn damage.
“Wind is a common factor that causes winter burn,” said William MacDonald, WVU Davis College of Agriculture, Natural Resources and Design forest pathology professor.
The southwest facing side of the plant typically has the most noticeable winter burn damage, especially if the plant has no protection from wind-induced withering.
MacDonald explains that winter burn damage could be reversed if you take steps to fix it now.
“April is the perfect time of year to prune boxwood plants because the plants haven’t started to sprout new growth,” he added.
To repair the plant and make way for healthy, new growth cut back the tips of any damaged branches—just above a living, green leaf. Use shears for smaller branches, and loppers for large branches that are 1-1.5 inches or bigger in diameter.
Help prevent winter burn damage by establishing boxwood plants that are suitable to West Virginia’s hardiness zone. The use of organic mulch around the plants will help maintain soil moisture.
Water boxwood plants during the winter months if the ground is not frozen for a length of time. During windy periods, cover the plants with burlap, which helps prevent further water loss.
“Anti-transpirants and anti-desiccants garden sprays can be applied to help retain moisture and prevent water loss,” advised MacDonald. “These compounds are sprayed directly onto the plant and protect plants from some fungal diseases, too.”
If leaves turn brown or tan after proper pruning of boxwood plants in the spring, it’s possible the plant is suffering from a leaf disease.
Common symptoms of disease include brown discoloration and presence of black fungal fruiting structures on leaves. These structures are commonly seen on dead leaves attacked by a fungus called Macrophoma. Another type of fungus, named Volutella, may cause similar symptoms as Macrophoma, but may produce orange-pink colored fruiting structures.
Specimens that show symptoms and signs of disease can be sent to WVU’s Plant and Pest Diagnostic Clinic for proper identification.
For more information on proper planting, pruning and plant diseases, contact your local office of the WVU Extension Service or visit www.ext.wvu.edu.
CONTACT: Cassie Waugh, WVU Extension Service
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