Rainy summer spurred growth of tree fungus diseases
This week, I was going to write about anthracnose affecting many of the trees in our area, but I came across a Penn State tree release that describes this summer’s tree problems.
This information is from the Penn State release:
If it isn’t one thing, then it’s another. Last year, we suffered through a drought, and this year we have so much rain that fungus diseases are rampant. Have you noticed trees with few leaves or leaves that are spotted and yellowâ¢ The dampness has promoted anthracnose — a fungus that affects trees such as maple, dogwood, ash, white oak and sycamore — across Pennsylvania. And lots of people have noticed.
Some sycamores have lost as many as 90 percent of their leaves this summer. Trees affected with anthracnose have brown and shriveled leaves that may progressively die and drop off. Although unsightly, the fungus usually does not kill trees. There are outbreaks of anthracnose in Pennsylvania whenever we have a wet spring. Many sycamores that had their leaves turn brown and fall, grew a second set of leaves that also died and now releafing for the third time.
Many trees in southern counties are refoliating, but trees in the northern half of the state have not fared as well and may not grow new leaves until next year. Still, according to Jim Finley, professor of forest resources, most will survive.
“We have gotten a lot of calls about it,” he says. “When folks saw so many oak trees losing their leaves in the northwest region of the state, they were a bit unnerved. But trees are going to recover.”
Anthracnose symptoms appear in early spring when fungal spores infect leaf buds. If conditions continue to be favorable for the spread of the fungus, as they have been this year, symptoms persist and worsen in late spring and early summer. Trees infected with anthracnose for consecutive years will weaken and become more vulnerable to other pests and diseases.
This year’s cool, damp weather has had far-reaching effects. Anthracnose has damaged trees in Michigan and Ohio, as well as Pennsylvania, and as far south as the mountains of the Carolinas. Every time we have a cold, wet spring there are outbreaks; and the colder and wetter the weather, the worse anthracnose is.
By the time people notice the problem, it is too late to do anything about the disease. There are fungicides that could be sprayed preventively to minimize the effects of anthracnose, but by the time you realize you have a problem, it is too late, and in most cases, it is impractical and/or prohibitively expensive to treat large shade trees.
Dogwoods in the landscape might be one tree to consider treating in future years. Anthracnose is a major cause of dogwood decline and death. Careful pruning, moderate fertilization, a light mulch and a couple of carefully timed fungicide sprays can go a long way to keeping dogwoods healthy and beautiful.
But, for most shade trees, anthracnose is a disease that makes them look bad in wet seasons, but does not kill the trees.
Fall is a great time for planting. So, take a walk around the yard. Note a tree may be needed or what shrubs need to be replaced.
Continue planting spring-flowering bulbs such as tulips, crocus, daffodils and hyacinths.
Garden tip: Fall is one of the best times to kill perennial weeds in the lawn, so spray weeds now for less weeds next year.