Q • For the past five years, our 30-year-old sycamore tree has leafed out every spring, then some of the leaves turn gray, wilt, then brown — and then the tree grows new leaves and seems fine. This year, it lost every leaf. I thought it was dead, but I fed the roots, and the tree rebudded and it is still green. I’ve kept it watered all summer. Other sycamores close to it have the same small loss every year, but never as much as this one and not total, as was the case this year. We live in Jefferson City. What is this disease? What can I do?
A • I can’t confirm the disease without seeing symptoms on leaves and twigs, but I suspect you’re describing sycamore anthracnose, a common fungal disease that infects new leaves during cool, wet weather in spring.
Once the tree is infected, symptoms develop and leaf drop occurs in the following weeks. Severity of infection is variable from year to year, depending on local weather conditions. As warmer temperatures arrive, no additional infection will occur, and a new crop of leaves will be produced. Certainly the extraordinary heat this summer and ongoing drought could be contributing to leaf loss this year. See our anthracnose Web page here: tinyurl.com/8p7n6fh.
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Susceptibility is also variable from tree to tree, and the American sycamore (Platanus occidentalis) is more susceptible than the very similar hybrid London planetree (Platanus x acerifolia). While chronic severe infections can weaken individual trees, sycamores are nonetheless surprisingly tolerant of this disease and may live for many years with the condition.
If fungicidal treatments are desired, I would recommend you search for an arborist certified by the International Society of Arboriculture in your area to treat your tree. Search at isa-arbor.com/faca/findArborist.aspx.
Arborists are also listed in the Yellow Pages under “tree service.”
Write to Chip Tynan at [email protected] or Horticultural Answer Service, Department PD, P.O. Box 299, St. Louis, Mo. 63166. Check his blog at: mobot.org/gardeninghelp/hilight.asp