Back in October I wrote about the spotted leaves in my neighbourhood.
It seems someone at The Globe and Mail read that entry and today explained these unsightly leaves on the front page of their Globe Toronto section. Here's what Andre Davidson of the Globe wrote:
The spots aren't ashes from Mount St. Helens reaching Toronto, or a byproduct of the city's new smoking laws, but the result of the increased prevalence of a common fungus known as Maple tar spot.
Tar spot is a fungal leaf disease caused by Rhytisma acerinum, a fungus that affects a number of plants, but is most commonly found on maple leaves.
Just like any other fungus, Maple tar spot loves water -- its spores thrive on wet spots. And because of some of the heavy rains we've had this summer and fall, it's flourishing now, says city forester Richard Ubbens. "It seems to come and go a bit even on an area basis," he says. "Some areas that seem to have more of it this year may not necessarily have as much next year."
My initial instinct was to pin this on Rhytisma acerinum, but I didn't want to jump to conclusions. Now that my suspicions have been confirmed, I won't rest until every trace of Rhytisma acerinum is eradicated in my neighbourhood.