Boxwood yellow lines - Ask Extension
My boxwood leaves are turning yellow then brown. Some leaves seems to have yellow lines or veins in them. I just noticed this in the last 2 weeks but ...
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Boxwood yellow lines #821155
Asked February 26, 2023, 2:52 PM EST
My boxwood leaves are turning yellow then brown. Some leaves seems to have yellow lines or veins in them. I just noticed this in the last 2 weeks but it seems to be getting worse. Please advise. Thank you!
Franklin County Ohio
Expert Response
Thank you for your question to Ask a Master Gardener Volunteer with eXtension.
I am so sorry to hear about your boxwood problem. Unfortunately, I do not have much good news for you.
From the pictures you sent in with your inquiry, the problem appears to be boxwood blight, which is becoming quite a problem here. (so much so that many nurseries are not selling boxwood or guaranteeing them if you do purchase them).
Please see the following for proper identification and further insight into this disease:
I am so sorry to hear about your boxwood problem. Unfortunately, I do not have much good news for you.
From the pictures you sent in with your inquiry, the problem appears to be boxwood blight, which is becoming quite a problem here. (so much so that many nurseries are not selling boxwood or guaranteeing them if you do purchase them).
Please see the following for proper identification and further insight into this disease:
https://extension.umd.edu/resource/boxwood-identify-and-manage-common-problems
https://hgic.clemson.edu/factsheet/boxwood-diseases-insect-pests/
https://extension.psu.edu/boxwood-diseases
https://newgarden.com/notes/boxwood-blight
https://www.extension.purdue.edu/extmedia/bp/bp-203-w.pdf
Best of luck to you.I have done a little further digging and opened up a leaf of boxwood to see orange/ yellow worms. I attached a photo. Please advise!
Thank you so much!
Eleanor
I am glad you persevered! (and sent a much closer picture of your damage). It is always difficult to try and make a diagnosis without very close up shots and adequate information. I believe the larvae you are seeing is the boxwood leafminer.
Boxwood leafminer damage may be mistaken for winter injury and vice versa. Both produce similar symptoms when viewed at a distance. There is no way to be certain if it’s one or the other without a close examination of the foliage. Adding to the challenge, it’s not uncommon to observe both leafminer damage and winter injury on the same plants, particularly at this time of the year.
I am attaching the following information:
As you read about this pest you will find the recommendation to use Imidacloprid, a systemic insecticide (Merit or Bayer Tree and Shrub Insect Control), which will control the larvae inside the leaves and does not require precise timing. This product should be applied in mid- to late April.
Hopefully this new information will be of use to you as you take the necessary action to protect your boxwoods!
Boxwood leafminer damage may be mistaken for winter injury and vice versa. Both produce similar symptoms when viewed at a distance. There is no way to be certain if it’s one or the other without a close examination of the foliage. Adding to the challenge, it’s not uncommon to observe both leafminer damage and winter injury on the same plants, particularly at this time of the year.
I am attaching the following information:
As you read about this pest you will find the recommendation to use Imidacloprid, a systemic insecticide (Merit or Bayer Tree and Shrub Insect Control), which will control the larvae inside the leaves and does not require precise timing. This product should be applied in mid- to late April.
Hopefully this new information will be of use to you as you take the necessary action to protect your boxwoods!
