Black spots and dropping leaves – Are your trees dying?
Right about now, the greater Madison and Milwaukee areas are experiencing symptoms of a foliar disease called Anthracnose.
Commonly affected tree species – Around southern Wisconsin we can expect to see Anthracnose on Maple, Ash, White Oak, Walnut and even Sycamore! Each of these Tree species are affected by a specific but related strain of the fungi classified within the Genus Gleosporium.
Anthracnose Symptoms – Generally, the symptoms if this disease cause irregular dark brown or black spots on the leaf tissue. If the infection is severe enough the leaves may curl, die and drop from the tree.
How did my trees get it? – The Anthracnose spore, which becomes the fungus, is very common in our area and will lay dormant until the optimal conditions arrive. These conditions are generally moist, cool periods (typical Southern WI in springtime).
How concerned should you be? – The good news is that Anthracnose is generally just superficial. But it will cause varying amounts of leaf drop depending on the severity and seasonal conditions. The exception is with Sycamore, where we commonly see twig dieback associated with the infection.
To treat or not to treat? – For on Maple, Ash, White Oak and Walnut: we do not generally recommend using any form of chemical treatment. Instead, the use of a nutrient and bio-stimulant soil injection will help assure that your trees weather the infection with as little long-term effects as possible. (Think of this as a science-based probiotic for trees!)
The Exception – If we diagnose Anthracnose in a Sycamore tree, we will strongly recommend a fungicide trunk injection. Anthracnose in sycamore will cause twig dieback and may severely stunt the tree.
Can I, as a Homeowner, help the tree? – Raking up the leaves and either burning or composting at high temperatures (140F and up) will destroy the spores and help to reduce the spore load in the coming seasons.
Just some notes:
You neighbors will most likely develop symptoms as well but don’t fret, it’s not your fault, this disease is nearly everywhere just waiting for the right environmental conditions.
You may experience an annual infection of varying degrees of severity, this is common. If this happens, we highly recommend either a tree growth hormone injection or a Bio-stimulant injection to reduce the overall stress on the tree.