From Maple Tar Spot To Anthracnose: What are Those Spots on Your Tree’s Leaves?


Vancouver, BC based tree service professionals discuss the group of tree diseases called leaf spot.

What Can Homeowners Do About Leaf Spot

The deciduous trees in this area of the world are some of the hardiest and loveliest trees anywhere. Silver maples and sugar maples are not only hardy, but have beautiful autumn foliage. Though they are resistant to many different kinds of attacks, the moist, warmer air that is coming can bring with it the perfect breeding ground for a nasty-looking group of tree diseases called leaf spot or leaf blotch. Normally leaf spot is seasonal and is only cosmetic, but there are situations where it can cause significant damage to your trees.

Spots on Leaves: Is It All Disease?

Just because your tree has leaves with spots does not automatically mean that your tree is infected with leaf spot. Both bacteria and fungi can cause leaf spot, but other environmental factors may be contributing to the problems that you are seeing on your trees. Fertilizer burn and overwatering can cause yellowing of leaves. Likewise, storm damage and pest infestation can show up in the tree’s leaves. This is why having a certified arborist look at the tree can be helpful in determining if treatment is needed.

Leaf Spot’s Most Common Culprits

As previously stated, bacterial and fungal infections are the main cause of leaf spot. Bacteria can cause problems if they have infected more of the tree than just the leaves. Fungi are the most common culprits of leaf spot. A few of the widely spread types of leaf spot will be detailed below.

  • Anthracnose: This particular disease starts by browning the leaf veins and then growing into spots that spread and kill early spring leaves. It affects many deciduous trees and hardwoods.
  • Cercospora Leaf Spot: The spots associated with this fungal infection start off red or purple then fade to gray or brown as the leaf dies.
  • Maple Tar Spot: This fungus presents first as a dark spot that eventually turns black and shriveled.They are often somewhat raised with a brown ring surrounding the “tar spot.”
  • Powdery Mildew: This one looks just like it sounds. It is a white powder that seems to cover leaves.

Treating and Preventing Leaf Spot

Though the leaves that are already affected will be lost, leaf spot is a treatable condition and will likely do no serious damage to the tree. It can even be ignored for the most part as long as it is not bothering the homeowner or the tree too much. There are strategies for removal if there is concern for tree health.

  • Keep leaves dry by watering with a soaker hose.
  • Tree trimming can prevent overcrowding of branches which promotes spread.
  • Use sterilized tree pruning tools to remove branches with affected leaves.
  • Test soil and fertilize if it is needed.
  • Use an antifungal spray.

Call in the Pros: What a Tree Service Company Can Do

All of the strategies above can be put into the capable hands of a certified arborist who will know how to correctly treat the particular disease or problem that is afflicting your tree. They are not only experts in tree removal, they are also experts in tree health care. The tree will not be removed unless it is deemed necessary.

About VI Tree Service

Since 1990, VI Tree Service has been caring for trees in Vancouver, BC and the surrounding areas. They have the right equipment and half a century of combined experience. Call today for a free quote.