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Trending in the Aisle: Black Tar Spot

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As summer comes to a close here in Boston and the cool mornings and evenings encourage the break out of sweaters and flannel shirts, we New Englanders,  look to the trees to begin preforming their colorful, autumn show.

There is a disturbing trend happening in the branches above, and it brings customers into the aisle of my Home Depot asking the question: What is wrong with my maple tree?

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The maple trees are suffering from a fungus that is called “Black Tar Spot”. The disease has been appearing for the past several years, but this year, because of the long, wet, spring, the affliction has, literately, raised the, "spotted-disease head", earlier, and to a broader range. The Norway maple, a variety of maple that is prominent in the forestry of New England, is the hardest hit.

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The symptoms start early in the season with a pale circular spot on the leaves, it looks like a small pale burn mark, translucent, exposing the leaf cells; then as the season progresses the circle turns black, and somewhat raised…looking as if, black tar was dripped onto the leaves. That is not the only unsightly symptom; the leaf itself starts too curly around the edges, and then the outside rolls up, it becomes an ugly brown, with black raised spots, and then the leaves drop from the tree prematurely…. becoming a crunchy, ugly, mess!

From all my research, I have found that this disease is more of a cosmetic problem, it is said that it does not affect, or harm, the life of the tree, but just causes the leaves to scar and fall early….uggg! 

How can defoliating early, not affect the trees life cycle? It seems to me that: the early leaf drop, and the bare branches, would disrupt many aspect of the autumnal routine; not to mention the factoring of less leaves, for the incredible display of fall colors that “leaf peepers” flock to Boston, and New England for.

Leaf cleanup is crucial, a continual cleanup, and raking, from this early point on, will help the fungal cycle to be broken, or at least minimize the spread. Each leaf carries the spores of the disease, the spores travel on the leaves, in the air, and through water particles. The disease can winter over in the ground if leaves are left  to decompose into the soil, and then the cycle begins again next season.

The early season rains in the North East this year eased the ability of the spores to spread, resulting in the noticeable, widespread, early browning of leaves…….that bring in the customers, and their concerns….”What is happening to my maple trees”?

I explain what I know, it is “Black Tar Spot”, and what my research has uncovered, and then I offer some advice:

  *Start fall cleanup now, do not let the leaves pile up; grab a few pack of yard waste bags now!

  *Purchase a Spring Tine Rake, this rake has wide spread tines that allow you to get into the garden and rake leaves around vegetation, and flowers that are still growing. We still have weeks and weeks until a frost comes and removing leaves from garden that is still flourishing is not an easy task, a spring tine rake will make it a bit easier.

  *Do not add diseased leaves to your home compost pile; bag them, then have them taken away, by the town or city.

 *Continue the process throughout the autumn. The final clean should be thorough!


Between the devouring of leaves by gypsy moth caterpillars, last year’s drought, the winter’s heavy snow burden, along with a very wet spring, and now this Black Tar Spot epidemic, the trees are tired, stressed, and need a little help….so cleanup!


Stop by your local Home Depot; pick up a few packs of yard waste bags now!

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This must never be a view from the past, or what fall use to look like! These are healthy Norway maples during peak foliage season!


Let us know if you see signs of “Black Tar Spot” on the trees in your neighborhood, give us your zip code......we all need to "Wake Up and Rake Up"!





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Posted 2017-08-31T17:37:39+0000  by Maureen_HD_BOS Maureen_HD_BOS