Streptomycetes Possibly on Boxwood bushes - Ask Extension
Ned advised on what to do about my Boxwoods
Knowledgebase
Streptomycetes Possibly on Boxwood bushes #851222
Asked September 25, 2023, 5:50 PM EDT
Ned advised on what to do about my Boxwoods
Cuyahoga County Ohio
Expert Response
Hi Laura,
Thank you for sending photos. They're very helpful, but it's still difficult to diagnose many plant diseases without being able to examine the plant.
Just from what I'm able to see, my best guess is your boxwoods have become infested with boxwood leafminers, insects that deposit eggs between the upper and lower surface of the leaves. The eggs hatch in early summer, and the leafminer maggots spend the season consuming the insides of the leaves. It is believed they take a break at some point during the summer and resume feeding just about this time of year.
What makes the situation worse is that birds often do further damage to the boxwoods while they feed on the insects.
This fact sheet offers more information as well as guidance on treating boxwoods with insecticides: https://bygl.osu.edu/node/2102
It's also possible the boxwoods have been targeted by the fungal disease boxwood blight, but that usually results in a fast and severe die-back of the branches. The disease is also characterized by black streaks on the stems, which I am not seeing in the photos you sent. Here is more info on boxwood blight: https://bygl.osu.edu/node/1359
If you want a certain diagnosis, you can send samples to Ohio State's C. Wayne Ellett Plant and Pest Diagnostic Clinic in Wooster. Information is at https://ppdc.osu.edu/ .
Good luck!
Thank you for sending photos. They're very helpful, but it's still difficult to diagnose many plant diseases without being able to examine the plant.
Just from what I'm able to see, my best guess is your boxwoods have become infested with boxwood leafminers, insects that deposit eggs between the upper and lower surface of the leaves. The eggs hatch in early summer, and the leafminer maggots spend the season consuming the insides of the leaves. It is believed they take a break at some point during the summer and resume feeding just about this time of year.
What makes the situation worse is that birds often do further damage to the boxwoods while they feed on the insects.
This fact sheet offers more information as well as guidance on treating boxwoods with insecticides: https://bygl.osu.edu/node/2102
It's also possible the boxwoods have been targeted by the fungal disease boxwood blight, but that usually results in a fast and severe die-back of the branches. The disease is also characterized by black streaks on the stems, which I am not seeing in the photos you sent. Here is more info on boxwood blight: https://bygl.osu.edu/node/1359
If you want a certain diagnosis, you can send samples to Ohio State's C. Wayne Ellett Plant and Pest Diagnostic Clinic in Wooster. Information is at https://ppdc.osu.edu/ .
Good luck!
Hello,
I sent you examples of the Boxwood that are infected, and I am wounding if you looked at the 3 sample that I sent you. If you look at them, what should I use to help the return to health.
Thank you
Laura Mihelick #0121148
Hi Laura,
Did you send the samples to the C. Wayne Ellett Plant and Pest Diagnostic Clinic (the place I had suggested)? I am a master gardener volunteer and don't work at the clinic, so I'm not able to tell you whether they arrived or what the diagnosis was.
You should be able to reach the clinic at<personal data hidden> or <personal data hidden>. Hopefully someone there will be able to assist you!
Did you send the samples to the C. Wayne Ellett Plant and Pest Diagnostic Clinic (the place I had suggested)? I am a master gardener volunteer and don't work at the clinic, so I'm not able to tell you whether they arrived or what the diagnosis was.
You should be able to reach the clinic at<personal data hidden> or <personal data hidden>. Hopefully someone there will be able to assist you!
