You may not have heard of boxwood blight, but it is a disease of boxwoods you do need to be aware of that seems to be making some inroads into Alabama. According to an update from Auburn University, diseased boxwoods have been identified in the Birmingham metro area and in the historic district of Huntsville.
Dave Bradford of Bradford Horticulture (BoxwoodDoctor.com) also told me his observations about boxwood blight in a recent email:
Early on, spots will appear with a darker circle around them on the leaf
There will be defoliation of the leaves
On limbs that are not dead, look for lesions along the green stem
It is easily confused with other more common Boxwood diseases
If any one finds these specific signs, they should check the info. sheet (in the link above) and collect a sample for the Plant Diagnostic Lab at the BBG
There are also good notes for Homeowners, Landscape Professionals, Nurseries, and Garden Centers.
Sprays are not very effective long term. Even If this disease doesn’t kill the Boxwood, it will become so unsightly that it will need to be removed from the landscape.
The information below was copied from the Plant Diagnostic Laboratory at Auburn University in the link above and refers to residential and commercial landscapes. For more information please refer to the link for the complete report.
Commercial and Residential Landscapes – Boxwood blight is most likely to be introduced into the landscape on diseased plant material. Localized spread from diseased plants within or to adjacent landscapes may also occur via rain or irrigation splash, contaminated clothing or shoes, hoses, or tools.
• Plant disease-resistant boxwood but be aware that these cultivars may harbor the pathogen without displaying symptoms. See Table 1 for list of disease-resistant boxwood.
• Purchase boxwood that originate from states where the disease is not found.
• Inspect boxwood at time of purchase for symptoms of boxwood blight
• Monitor newly established boxwood plantings for blight symptoms for 60 to 90 days.
• Remove diseased plants and bag them from disposal.
• Surface rather than overhead water established boxwood.
• Should suspicious symptoms appear on boxwood, submit a sample for diagnosis to the Plant Diagnostic Laboratory.
• Remove, bag and, discard leaf litter from soil surface from beds where diseased boxwood have been removed.
Do not reestablish boxwood into landscape beds where disease plants were removed and replace with selections of Dwarf Yaupon, Japanese (little leaf), or dwarf inkberry holly.
• Clean tools with a surface disinfectant like isopropyl alcohol after trimming or removing diseased boxwood.
• Clean tools between landscapes.
• For highly valued boxwood, apply protective fungicide listed in Table 2 when plants are vulnerable to attack and weather favors disease spread.
I hope you find this information helpful. We’ll do our part by continuing to monitor any new developments about boxwood blight in Alabama and will pass along information as it becomes available from Auburn University Extension Service and other experts in the horticultural industry.