What is attacking my dogwood?
I have a white Dogwood tree less than five years old. I noticed that the leaves are curling and have a powdery substance on them. Upon further inspection I saw that the bark of the tree is split and some has been stripped completely away. Looking closer I observed small wholes in the bark. I saw some small winged insects on the trunk. Can this be treated?
Anne Arundel County Maryland
Please send us photos of the tree so we can see what you may be dealing with. Send photos of the whole tree, around the base, affected foliage , and trunk.
The white spots on the foliage sounds like powdery mildew, a fungal disease. There is a range of susceptibility among dogwood to 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. http://extension.umd.edu/hgic/powdery-mildew-trees-and-shrubs
This looks like old trunk damage to the dogwood that has tried to heal over. The crotch shows some occluded bark that may become become a weak spot that would weaken the crotch. There is nothing that can be done and no chemical controls are recommended.
The white spots on the trunk are lichens and they can occur on a mature tree but they are not a reason for decline. They are an indicator of good air quality http://extension.umd.edu/hgic/lichens-trees-and-shrubs
We noticed that there are improperly pruned branches on the tree leaving stubs. It is recommended to prune broken branches back to the trunk. Do not cut the branch flush with the trunk removing the collar. The collar is an area of natural shedding that contains protective tissue that encourages healing.
Take a look at our pruning publication for more pruning information http://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs/...
As mentioned in our first response, there may be some powdery mildew on the foliage. At this point all you can do is prune properly, keep the tree watered during dry periods, make sure mulch is no thicker than several inches and away from the base of the trunk. The tree will limp along and you will eventually have to replace it. If you want another dogwood, select species that are resistant to powdery mildew and/or disease like spot anthracnose or another tree species based on your site and mature height and width. Dogwoods are understory trees and grow best in morning sun and afternoon shade. See our publication on dogwood http://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs/...