Composting Maple Leaves with Black Spot

by Katherine
(Kitchener, Ontario)

Hi,
In your last newsletter you wrote about the benefits of composting leaves. I have access to a lot of leaves in my area but many of the leaves are from maple trees which are infected with black spots (I think they are known as tar spots). Is it o.k. to use these leaves in my garden or should I forego them?


Doug says that if your garden is close to this garden, then you probably have this as well. In general, conventional wisdom is to burn or destroy all leaves from trees with tar spot.

If you compost them or grind/mow/chew them up and mulch them over plants, breaking up the overwintering fungal bodies will prevent the spores from maturing.

Leaving them in piles on the ground is not the best problem-breaking solution.

So if you do something to them, you'll be fine. If you just let them sit, then you're risking further infecting your own trees.

Having said that, it is clear that tar spot doesn't bother the health of trees. It's unsightly and bothers us more than the tree.