5 Common Tree Diseases In Ohio And How You Can Prevent Them

Ohio Trees

5 Common Tree Diseases In Ohio And How You Can Prevent Them

Ohio is home to a diverse range of tree species, each with their own unique set of challenges when it comes to tree health. From pests and diseases to environmental factors, there are many things that can put stress on a tree and impact its ability to thrive. In this blog, we cover the 5 most common tree diseases in Ohio and offer ways that you can prevent them from occurring.

1. Powdery Mildew

If you’ve seen a tree whose leaves look like they are covered in sugar or salt, then you likely saw a tree that was suffering from Powdery Mildew. Powdery Mildew is a common fungal infection that interferes with the photosynthesis process in trees, making it difficult for the tree to produce energy. Unlike many other arbor diseases that focus on one or two types of trees, this disease hits a wide variety. Put short, powdery mildew is the “common cold” of trees. While Powdery Mildew is not typically fatal, it can cause significant damage to your trees if left untreated.

In order to prevent this disease from occurring, we recommend doing the following:

  • Plant your trees in open locations that have good airflow, sunlight, and plenty of growing room
  • Selectively prune overcrowded areas to increase air circulation around your plants; this helps to reduce relative humidity
  • Immediately remove infected branches or leaves that have fallen
  • Clean and disinfect tools before next use

2. Apple Scab

Apple and crabapple trees, whether wild or cultivated, are highly vulnerable to Apple Scab, a type of fungus that targets both the leaves and fruits of the tree. This fungal disease is characterized by the appearance of pale yellow or olive-green spots on the top of the foliage and darker patches on the undersides of affected areas. The leaves may even curl up and fall off prematurely, while the fruits can exhibit signs of rot that closely resemble the scab of a healing skin injury. If left untreated, Apple Scab can cause significant damage to the tree and greatly reduce its fruit yield.

If you want to prevent Apple Scab from occurring in your trees, then we recommend the following:

  • Choose scab-resistant varieties of apple or crabapple trees
  • Rake up and dispose of any fallen leaves or fruit on a regular basis. Never leave fallen leaves or fruit on the ground over winter
  • Prune your trees as needed to keep their crowns open so that light and air can move through
  • Irrigate your trees during early morning hours, and don’t use overhead sprays that will leave your fruit and leaves wet

3. Thousand Cankers Disease (TSD)

Thousand Cankers Disease is carried by a tiny insect called the Walnut Twig Beetle. The beetle is known to burrow into the bark of the tree, leaving behind a fungal pathogen that attacks the tree’s circulatory system. This fungal disease is responsible for significant damage to the tree’s bark and the growth of cankers, which appear as blemishes on the bark’s surface. The damage inflicted on the tree’s circulatory system can significantly disrupt the tree’s ability to transport water and nutrients, leading to a decline in its overall health and potentially causing its death.

To prevent this disease from occurring in your trees, we recommend doing the following:

  • Regularly inspect your trees for symptoms of TSD (yellowing, wilting leaves, dead limbs in upper part of tree)
  • Maintain overall tree health by watering regularly and avoiding physical damage whenever possible
  • Avoid moving firewood, since infected beetles may be present in the bark

4. Needlecasts

If you have coniferous evergreens like Douglas firs, pines, or spruces, you may be aware of the common fungal disease known as Needlecast. This disease specifically infects the needles of the trees, causing them to change color from yellow to purplish-brown or even black, before ultimately falling off. This disease tends to attack new growth, so it usually shows up on young needles during the spring and fall, after having thrived on infected ones throughout the winter.

In order to prevent Needlecasts from occurring in your coniferous evergreens, we recommend doing the following:

  • Purchase trees grown from local seed sources. These trees will be better adapted to the local conditions and are more likely to resist disease
  • Avoid planting your trees in shady areas where humidity and moisture remain high for extended periods of time

5. Cedar Apple Rust

Cedar Apple Rust is a fungal disease that can affect various tree species such as apple, crabapple, and red cedar trees. The primary symptom of this disease is the development of yellow spots on the leaves, which can eventually turn orange. If you suspect that your trees may be affected by Cedar Apple Rust, it’s important to act quickly in order to prevent the disease from spreading further. If you don’t, then your trees may suffer from premature defoliation and will see a decline in fruit quality, and in some cases, might even die.

In order to prevent Cedar Apple Rust from occurring in your trees, we recommend the following:

  • Work with a professional arborist to identify and treat the affected trees with fungicides and other preventive measures
  • Maintain your trees’ overall health by pruning, watering, and fertilizing
  • Dispose of unwanted apples, crabapples, or junipers


Now that you know about the 5 most common tree diseases in the Ohio and ways to prevent them from occurring, you should feel better about preparing your yard for the spring and summer seasons. At the end of the day, protecting your trees not only means that you’re making a difference in the environment, but it also means you are ensuring the safety of your property and loved ones. If you have any questions or need assistance evaluating the current health of the trees on your property, contact our team today. Our team of licensed arborists are happy to walk you through the health inspection process and offer healing solutions for your trees.

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