The black death, a cold black heart, fear of the dark, black cats, don’t go to the dark side! The idea that something that is dark or black is in some way evil is deeply engrained in our culture. Many of these instances are for good reason. Thanks to this prevailing opinion, a very common question Arborist get asked often is one he already knows the answer to without even looking. “What is this black stuff all over my maple leaves!?”
Tar spot is one of the most common fungal infections of maple trees in the area. Like most leaf affecting fungus, it all starts in the spring when spores released from the infection on last years leaves are released just as the new foliage from this year is developing. Any time a spore manages to find its way to the soft delicate tissue of a brand new leaf it can germinate and a new spot is born. First appearing as a slightly faded yellow mark, it will soon become a raised black blotch by July and will remain an eyesore for the rest of the year.
Fortunately for your tree that’s all it is, an eyesore. Tar spot causes nothing more then cosmetic damage to the leaves of your tree and it requires no help from us. Although absolutely terrifying in appearance to the concerned tree lover, this fungus is merely using the leaves as a vehicle for reproduction. If you don’t mind the sight of it then there is no control necessary. If the thought of your prize maple tree covered in reproducing microscopic fungi sickens you to your core, a descant amount of control can be obtained by raking up and disposing of infected leaves in the fall. Timely applications of the proper fungicide by an Ostvig Tree Care Arborist can be made in cases where disposal of infected leaves is not possible.