Growing strong and healthy trees can be an incredible investment. Not only is there a financial investment at the beginning, but finding a new home for your tree requires strategic planning. You’ll also have to consider the correct amount of food and water your tree will require. Most of all, your tree will require a large investment of time. All of these things considered, you’re putting in a lot of time, energy and resources into making sure your tree has everything it needs to thrive.
As soon as you start seeing irregularities in your trees, you start thinking the worst. Is my tree ok? Is it disease infected? Is my tree dying? One of the things many maple tree owners see is that the leaves start producing black spots on them. If you have the same scenario going on with your tree, don’t panic, this is a very common fungus disease called tar spot and is often seen on the Norway Maple, Silver Maple and the Freeman's Maple.
Tar Spot can look extremely bad in some cases, but rarely does it ever cause more than an aesthetic blemish to your tree. In general, those spots will become apparent around early to mid June and will peak around late August or early September. The good news is that Tar Spot is fairly benign and will rarely cause any health concerns to your Maple tree. If you’re uncertain if you have Tar Spot on your tree then you should contact a local arborist near you to confirm and to structure a disease management program specifically for you.
How do you treat black spots on maple leaves?
If the presence of tar spot on your leaves is concerning to you, you can have an arborist and pesticide applicator apply an effective dose of fungicide the following spring season. Going through with this is usually only recommended when you have persistent tar spot or it’s extremely prevalent in your immediate area.
Most arborists will caution you that spraying a fungicide on your leaves will only be effective if you treat every single leaf on your tree. This can get really challenging if you have a mature tree with many branches and hundreds or thousands of leaves on it.
Will tar spot kill a maple tree?
No, tar spot does not kill maple trees. For the most part, this fungus creates a cosmetic issue and will not go further than that. In many cases, tar spot does not even cause serious defoliation. This fungus does cause unsightly marks on tree leaves and may even spread from one tree to another but it does not pose a serious threat to your maple tree.
Is tar spot preventable?
The best way to prevent this fungus from occurring the following season is by raking and disposing of all the leaves that fall to the ground. Since it’s a fungus that is currently living on your leaves, you’ve got to kill them. You can dispose of them by burning them (law permitting), burying them, or hot composting at a temperature of at least 140 degrees. If you’re going to use hot compost as a method of elimination just remember to consistently turn the leaves so that the ones on the outside are moved toward the inside where it’s hot and where the fungi is being killed off.
How do I know if my maple tree is dying?
Maple trees are one of the country’s top 10 favorite trees. It's easy to understand why since it’s a very robust tree with beautifully shaped leaves and extremely colorful foliage. They grow strong, tall and prominent and can live very long and healthy lives. Unfortunately maple trees can grow sick if its environment isn’t right so if you see evident signs that it’s struggling, you should take immediate action to save it.
Here are some signs to look for (especially during the growing seasons):
- Partial or complete defoliation
- Yellowing or browning of leaves
- Curling of leaves
- Damaged bark or branches in the form of legions
- Appearance of fungal fruiting bodies
In general, Maple trees are very majestic, beautiful, healthy and resilient trees. Although it can be scary to look at its leaves and see “marks” on them, tar spot is a common occurrence and will not cause harm to your tree. However, they are not disease resistant and they can die from improper nourishment if left untreated. Don’t panic, it’s obvious when a maple isn’t doing well. Until then, enjoy all the benefits they have to offer.