Japanese Maple Disease #868519

Asked May 15, 2024, 10:42 AM EDT

I have a Japanese Maple on the west side of my home beside knockout roses. The roses appear to have Rose Rosette Disease (RRD). They look like internet pictures of roses with RRD. Now the Japanese Maple looks diseased. Based on internet advice, I assume the roses can't be saved. Is there any treatment you can recommend to save the Japanese Maple?

Frederick County Maryland

Expert Response

You don't have to worry about your Japanese Maple - it can't get Rose Rosette Disease.
It's not uncommon for people to think they have this disease on their roses when they may actually not. We would need to see more clearly focused photos of your rose (which can be attached directly to this reply) to tell whether it has RRD. 
New growth on Knock-Out roses naturally have red leaves at first.
You may have already seen it but here is our page on RRD:


Thank you Christine for your response.  My question is regarding the Japanese Maple.  It is diseased.  Could you look at the pictures of the Japanese Maple and let me know what I should do to treat what looks like a fungal disease?  Thanks.

The Question Asker Replied May 15, 2024, 3:04 PM EDT

I accidentally posted a picture of the rose instead of the Japanese Maple.  Here is the 2nd Japanese Maple picture.

The Question Asker Replied May 15, 2024, 3:06 PM EDT
We do not see any indications of a disease on the Japanese Maple. There is what looks to be lichen on the bark, which is normal and harmless, but no indications of fungal dieback or scale insects, the only two issues we occasionally see on this species. Are there areas of dead branches or foliage with leaf spot? (The latter of which is not a serious threat to plant health.) As to the bare zone at the top of the plant, that can be normal but may be influenced by how much summer sun the plant receives and if it's been previously stressed (such as by drought). We weren't certain if you were concerned about the rose virus potentially infecting the maple, but that won't happen as that particular virus only uses roses as hosts.

Thank you!  I didn't want to lose the maple.  The roses are a lost cause!
On Wed, May 15, 2024 at 5:03 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied May 15, 2024, 6:11 PM EDT

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