When most people think about what it takes to keep their trees healthy, they imagine a simple regimen of watering, fertilizing, and pruning. And while this will preserve your plants under most conditions, there are some issues that go beyond simple maintenance. Cankers are a particularly serious threat for all Michiganders trying to keep healthy trees in their yards. A broad category of diseases that can result from fungal or bacterial infections, cankers cause serious damage and are hard to get rid of. It’s thus important to catch these threats early and take evasive action as soon as they arise.


A canker is a sore that appears on your tree after it has been infected by tree diseases. Both fungi and bacteria can cause cankers, with each type of organism producing different specific symptoms. The most common kinds of cankers include beech bark disease, Phomopsis juniper canker disease, chestnut blight, and walnut canker disease.

Canker disease usually starts when your tree gets wounded, whether due to storm damage, insect attacks, or mistakes made while pruning. When there is a large injury on the trunk, bacteria, and fungi have an easy time getting inside and spreading. They eventually infect the entire wounded area. Many types of canker infections cause large, ridged calluses to form on your trees, making them easy to identify. But some versions of canker disease, such as chestnut blight, do not create the same large ridges, so it’s more difficult for you to find and get rid of them.

As cankers get larger and more serious, they will split the bark that separates healthy and diseased tissue. This causes that bark to turn darker in color, ooze moisture, and develop a foul smell. Canker disease also causes leaves to grow smaller and shrivel, and it can affect the vascular system of your tree. Over time, these issues can lead to branch dieback or even kill the entire plant.

In addition to its severe negative effects, canker disease is so serious because it is hard to get rid of. There are no chemical treatments that consistently eliminate this disease, meaning once the disease has gotten underway, there is little you can do to stop it. In some cases, you can prune diseased parts of the tree, so that only the healthy part continues to grow. But this is dangerous, as the area you pruned can become infected, so you should only do it when you have the assistance of a professional and you are sure you can get rid of the entire infected area.


Given the lack of reliable chemical cures, the most effective way to deal with tree canker disease is to give your trees all the care and nutrients they need to grow strong regardless. Through proper maintenance, you can stop other diseases from attacking your trees while watering and nourishing them to maximal health. As a result, they will be able to grow strong and sturdy even with canker disease.

Safari Tree offers a comprehensive care program for trees across Michigan. To bolster your plants against cankers and other infections, we can:
  • Apply Dormant Oil- At the start of each spring, we apply a dormant oil that prevents insects from harming the tree.

  • Feed the Roots- After applying a dormant oil, we carry out deep root feeding that gives your trees all the nutrients they need to grow. This strengthens them and allows them to take full advantage of the growing season, even while fending off a canker infection.

  • Fungal & Insecticide Spray- During the summer, we apply three rounds of spray to get rid of fungi and insects. This prevents these organisms from compounding the damage of a canker infection by attacking and weakening the tree.
  • Fall Feeding- Once autumn begins, we carry out the second round of feeding. This allows your trees to stay strong during the winter even while dealing with cankers.

  • Anti-Desiccant Treatment- Before winter begins, we spray your trees so they don’t dry out in the cold weather. Drying would make them more vulnerable to damage from the cankers.

For more information on canker disease or to get a free estimate on tree care, contact Safari Tree today.