My boxwood is being eaten alive by something (see brown sections in images). At first I assume it was boxwood moth pupae, but I’ve not seen any sign of caterpillars or the cocoon. I realized then that the white things on the boxwood is psyllid. It’s all over the boxwood hedge so it’s heavily infested. My questions: 1) does psyllid do the kind of damage seen in the images? 2) how do I treat the boxwood for psyllid? 3) What else is this boxwood infected with?
I have sprayed BTK just in case there was boxwood moth pupae because they’re difficult to see.
Thank you for contacting the Toronto Master Gardeners, and sorry to hear that your boxwood is being eaten!
It’s difficult to accurately diagnose without seeing the brown leaves up close, but if you are seeing white fluffy insects, it could be psyllid as you suggested. Assuming you’re in Toronto, your plant is likely suffering from one of the following: boxwood psyllid, boxwood blight, box tree moth, boxwood spider mite or boxwood leaf miners.
We have numerous posts on our website concerning boxwood and their diseases. Simply type “Boxwood” into the “Find it Here” bar located to the right of the page. You can also take a look at this previous post concerning brown boxwood leaves.
Are you noticing the leaves in the affected area are started to become a ‘cupped’ shape? That is a key symptom of psyllid.
The patch of brown leaves looks like it could also be blight. The symptoms are circular leaf spots with dark margins and black-brown streaking on stems. As the disease progresses the leaves will drop till the plant is completely defoliated. The roots of the plant are not affected so if the fungus is detected early you may be able to save an infected plant by removing the diseased portions. Be sure to disinfect your tools after working with diseased plant material and avoid working with healthy plants after dealing with the diseased ones as the sticky fungal spores can adhere to your clothing and other equipment. Otherwise, diseased plants should be removed and sent to landfill. Never compost diseased plants or leaf debris or include in municipal garden waste.
Lastly, check out this link for Boxwood alternatives should you decide to replace them.