I have two large ornamental cherry trees that the tree service I use have...
I have two large ornamental cherry trees that the tree service I use have diagnosed as having brown rot. They are suggesting multiple spraying per year, I'd hate to lose these trees, but is it worth the effort or are these trees doomed?
For the last few years ornamental cherries, particularly Kwanzan cherries have been prone to brown rot. This is a fairly new occurrence. Although brown rot is a very common disease that infects fruit trees such as peach and cherry and the reason they need to be sprayed multiple times beginning when they are blooming. Treating trees your size would be problematic as fungicides need to be applied starting at bloom stage and then again every week to two weeks into the summer.
The disease seems to target the smaller branches first and can cause some die back. It eventually may target larger branches. Because this disease is fairly new we do not have a lot of information on it. It may help to have the trees pruned, certainly any dead branches should be removed. Thinning out the tree canopy may help to reduce moisture which promotes fungal diseases. Prune the tree during the summer or fall when the weather is dry to prevent spreading the disease.
Another piece of information about ornamental cherry trees in Maryland is that they are not long lived trees. They have about a 25-35 year life span. If your trees are older it most likely is not worth the cost of treating them.