Q. All three of my beautiful Ornamental Cherry trees are full of brown leaves. It’s as if the leaves from fall didn’t drop. I took a branch to the Master Gardeners at the Farmer’s Market, but they didn’t know what it might be. They told me to pick the leaves off, but the trees are ten years old and huge. I don’t have a ladder tall enough. All the new leaves are green. My son is getting married this summer, I will have tons of company, and they look horrible. Yet I hate to cut these beautiful trees down if the leaves just didn’t blow off due to our mild winter. Your advice is much appreciated. I saw the same thing on a cherry tree in Olympia a few weeks ago. Bonnie Westmark – Puyallup, WA
A. It sounds to me like you Ornamental Cherries have a disease called Brown Rot. This is a fungal disease that will attack flowers and leaves. The diseased flowers and leaves eventually turn brown and fail to senesce (a fancy horticultural term for drop). The failure to senesce works to the advantage of the disease. The infected brown leaves contain spores that are carried through to the new season. The spores then germinate from the diseased leaves and flowers forming a grayish fuzz when conditions are favorable (read cool wet spring). Eventually the disease can spread into smaller branches (twigs). Therefore the condition you describe is not likely due to our mild winters but rather Brown Rot. If you intend to keep these trees you will need to remove tree debris below the tree since some infected leaves will fall. If you cannot reach the tree yourself you should contract a certified arborist to clean out the infected twigs and leaves. The cuts should be made into healthy tissue below the infection. I recommended the pruner’s blades be cleaned with rubbing alcohol if a cut is made into diseased tissue. This prevents the spread of the disease via pruning. A certified arborist can also recommend the appropriate time in spring to make a fungicide application if necessary.