Knowledgebase
Boxwood Leafminer-how to treat #845754
Asked August 15, 2023, 11:39 AM EDT
I am pretty sure that my boxwoods are afflicted with the leaf miner blight. There are brown spots on many of the leaves and though they look a little better now than they did in spring, they have lost a lot of foliage this year. Is there anything I can do to save them/treat them? Thank you.
Wayne County Michigan
Expert Response
Hi Rachel,
I can't be sure if your boxwood have leafminer from the photos.
Here is an article from MSU on boxwood leafminer with helpful hints on how to determine if that is what is impacting your plants.
Here is more information from Missouri Botanical Garden with lots of photos.
It is too late to treat boxwood leafminer. There is a small window of time for chemical treatment in summer. If you have a significant number of boxwood, you may want to hire a professional for treatment. If they spray outside the window of time that adult leafminers are active, it will be ineffective.
If you dissect a few leaves and decide it is not leafminer, you can reply to this email and discuss other possibilities and strategies.
Lindsey K. Kerr, MS, MHP (she, her, hers)
Consumer Horticulture Educator
Michigan State University Extension
