Native dogwood tree in my front yard in Pikesville, more than 30 years old....
Native dogwood tree in my front yard in Pikesville, more than 30 years old. Facing west, it gets afternoon sun, although there are many tall trees nearby. No pesticides have been used, and the lawn on which it is located was last fertilized in the fall. Mulch was applied earlier this summer. All the leaves are lighter in color between the veins, while the veins are darker green. It looks as though the darker pigment between the veins is disappearing. Some of the leaves have looked shriveled and dry. There are no anthracnose-types spots visible.
We would like to see photos of the whole tree and the affected foliage. Dogwoods in general can be susceptible to several insect and disease problems such as borers, scale insects, powdery mildew, leaf spots, soil compaction, etc. Has anything changed around the root system of the dogwood? You will have to look for this. At this point all you can do is keep the tree well watered during dry periods.
See our dogwood publication for more information http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/not_updated/hg12_IPM...
Three photos of the leaves are attached. Leaves on the entire tree appear to be affected.
Note that although the photos exaggerate the intensity of the red color or the spots and veins, they are definitely red. When I first noticed a problem about 2 weeks ago, the leaves looked wrinkled, and their green coloration seemed spotty.
There have been no changes to the area where the tree is located. I do have a commercial lawn cutting service, but the area around the tree is grass-free. As far as watering, we have had a lot of rain, so do you think that I should supplement the water?
In your photos we noticed some dieback and looks like the leaves were subject to powdery mildew, a fungal disease. You may want to check with your lawn service and make sure no broadleaf herbicides were sprayed in the area for weed control.
See our dogwood publication on management and control for powdery mildew. The best recommendation is to plant powdery mildew resistant varieties in the future. Pruning for air circulation may help. You will have to monitor the plant in the future and decide if you want to spray fungicides or horticultural oil products listed for powdery mildew. This disease does not kill the plant but can weaken it.
Mulch the area under the tree with about two inches of mulch and keep away from the base of the trunk. This will help conserve soil moisture and keep the lawn mower away from the tree. Water during dry periods.
Powdery mildew even if I haven't noticed a powdery film on leaf surfaces? First notice of problem was that leaves had patchy areas of green instead of each leaf's being completely green.
As mentioned in our publication in some years the the powdery film may not be evident. It is not as obvious for example, as powdery mildew on lilac.
All you can do is monitor the tree throughout the growing season and keep well watered during dry periods. See above response.