Infected tree Leaves

Question: The image that I will attach is of two infected leaves among numerous (all leaves that have fallen, at least almost 100). This tree is next to a Black Walnut Tree. I have planted plants and bushes that should thrive living under Walnut Tree.
My question is : will the leaves that look like the leaves in the picture be infectious and harm the plants and bushes and shrub such as Cherry Laurel , Azaleas, Hydrangeas. Astibles, Cone Flowers etc?

responder: The Question Asker Replied July 10, 2023, 8:41 PM EDT
response: I added a photo of the tree that the leaves came from reference my previous question sent today 10 Jul 2023 with the photo of two infected leaves.

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 11, 2023, 3:42 PM EDT
response: Unfortunately we can't see enough detail in the leaf photo (file is too small) to determine the identify of the tree sample, and the second photo is too far away for us to recognize leaf shape as well. Are you able to take another close-up photo of the fallen leaves, please? Do you happen to know what type of tree it is? (Maybe River Birch? Hackberry?)  Impacts from a Black Walnut are likely not an issue in this case. This is probably a minor insect or disease outbreak that isn't going to affect the tree's long-term health, possibly coupled with drought stress from our ongoing shortage of rainfall so far this year. If you aren't already, you can monitor it for watering needs if you need to prioritize what to water in the landscape, since tree decline from drought sometimes doesn't fully manifest until years later when nothing can be done to reverse it.  It's not likely whatever is causing the tree leaves to become spotty and/or distorted and shed will affect the perennials and shrubs below, but once we can more clearly see its symptoms, we can provide more feedback.  Miri

responder: The Question Asker Replied July 13, 2023, 9:21 AM EDT
response: Sent from my iPhone On Jul 11, 2023, at 3:42 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: The Question Asker Replied July 13, 2023, 1:07 PM EDT

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 13, 2023, 4:33 PM EDT
response: Thank you for the additional photos. The leaf shape combined with the bark characteristics suggests this tree is a Hackberry, a good native species to have for its wildlife value. Hackberry is susceptible to developing a few types of cosmetic leaf damage from insects that form galls (a little like a plant tumor, but not serious), often in leaves. This particular case resembles Hackberry Blister Gall, though we can't tell for certain. (Here is another photo example in better lighting, though it's a case with less gall than your foliage has.) These are native insects and they do not cause long-term or substantial harm to the tree and can be ignored. You can rake-up and dispose of the fallen leaves, both now and in autumn if you wanted to reduce the insect population a bit, though it's not a foolproof way of preventing their return in a future year.  If you would like a second opinion and an evaluation of the tree in case any unrelated issues are causing it stress, you can have it assessed by a certified arborist. (Some arborists are employed by tree-care companies but others consult independently.) They can help confirm the ID of the tree as well as the organism causing these symptoms. We do not recommend the use of a pesticide in cases like this because they could risk harming pollinators or beneficial insects, and Hackberry is also the caterpillar host plant for several local butterflies.  With regards to your question about the ability of this phenomenon to spread to other garden plants, it will not if the gall-forming insect we identified as the culprit is indeed responsible. (Even if this was caused by a fungus, it still would be unlikely to affect anything else below.) The gall-makers are specific to hackberry and will not infest the shrubs and perennials you asked about.  Miri

responder: The Question Asker Replied July 13, 2023, 8:20 PM EDT
response: ISent from my iPhone On Jul 13, 2023, at 4:33 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: The Question Asker Replied July 13, 2023, 8:33 PM EDT
response: Thank you so much Miri.I live in a small HOA development of 3 Courts with a total of 48 town homes. I live in the the 3rd Court in a one level townhouse that borders on HOA open area that has about 4 trees. I volunteered to create a garden type area (in what was a neglected area that is located under the Walnut and Hackleberry Tree. There is also a Magnolia and Oak Tree in this small area at the end of Court 3. Picking up Magnolia leaves and up to about a thousand walnuts when in bloom, I actually wear a helmet when picking up Walnuts and do have help from a friend of mine who is still working but helps me on his off time.I am a 77 yr old Army Nurse widow who believes in giving back to the community.I really appreciate your and other MD Extension staff for helping me.  V/r,Pat

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 14, 2023, 8:58 AM EDT
response: You're very welcome!