EIGHT OUT OF MY TEN BOXWOODS ARE EITHER DEAD OR DYING.
tHEY ARE ABOUT 12 YEARS OLD AND HAVE DONE WELL WITHOUT MUCH HELP. iN THE LAST MONTH, THEY GOT VERY SICK. iS THIS A BLIGHT/INFECTION. i DO NOT WANT TO REPLACE THEM ONLY TO FACE MORE FATALITIES.
Thank you for contacting the Toronto Master Gardeners about your ‘dead or dying’ boxwoods. Unfortunately, boxwoods in the Toronto area have been affected by either boxwood blight
or box tree moth. Box tree moth has been the most recent concern (detected in Toronto in August, 2018), which may be what has been affecting your boxwoods. The caterpillars (larval stage of the box tree moth) would have been present toward the beginning of May and may continue through September. They eat the leaves and produce a webbing, in effect defoliating the shrub. You mention that you’ve only noticed this recently. Box tree caterpillars can be controlled by the use of BTK, usually available at garden centers and other retail stores.
Boxwood blight is a fungal disease which eventually causes the leaves to drop–it thrives in warm, humid conditions. It can be controlled by removing and disposing the dead plant material with garbage (not garden waste) and making sure that your tools are disinfected. Hopefully they are not ‘dead’ and can be brought back to health.
More information and excellent photos are included in the more comprehensive links below. Your box woods may not be dead and will most likely recover if you can control the infestations as soon as possible. We hope that this information will help you determine the problem with your box woods and prevent further issues with them.