How to Identify Fungal and Bacterial Damage on Your Trees and Plants

You may be surprised at the amount of trees and plants that are destroyed by fungal and bacterial diseases every year. Even in well-kept yards, fungi and bacteria can quickly grow and take over your trees and plants. Managing these invaders is an important part of good plant healthcare. By taking the time to learn about the most common fungi and bacteria to affect trees and plants in Ohio and Indiana, you are better equipped to identify damage and put a stop to it before the damage gets out of control.

Common Fungal Diseases That Damage Trees and Plants

Anthracnose — Cause and Symptoms

Anthracnose is a fungal disease that affects a wide variety of trees including ash, white oak, maple, sycamore, dogwood, elm, birch, hickory and others. The type of fungus that causes Anthracnose is host-specific and depends on the variety of tree — so, for example, a fungus that causes Anthracnose in a maple tree could not carry over to an oak tree.

Even though Anthracnose damages the trees’ foliage, it thankfully does not result in tree fatality. To keep your trees in your landscape strong and healthy, watch out for the following symptoms:

• Irregular spots and blotches on leaves
• Curling or distorted leaves on new growth
• Branch cankers (specific to certain tree species, like sycamore and dogwood)

Powdery Mildew — Cause and Symptoms

Powdery mildew affects a variety of plants and can inhibit the growth of your plants if not remedied. Powdery mildew spores usually travel into gardens by wind and thrive in warm, dry climates. Plants with lack of air circulation or those located in shady areas are more susceptible to this fungus damage.

Your plants may have powdery mildew fungus damage if you see these symptoms:

• The plant’s leaves are covered in a light, flour-like dusting
• Circular, powdery white spots on the plant’s leaves or stems
• Disfigurement of leaves and new, growing tips

Thousand Cankers Disease — Cause and Symptoms

Members of the black walnut family, like oak trees and hickory trees, are very susceptible to developing Thousand Cankers Disease, which emerged in the western United States and has made its way to the midwest region. Thousand Cankers Disease, which is caused by the Geosmithia morbida fungus, progresses quickly and can destroy a tree in as little as three years. The fungus is carried by the walnut twig beetle, which tends to be more active between April and October.

In Ohio specifically, oak and hickory trees make up more than half of forested land. If you have an oak or hickory tree in your home’s landscape, you’ll want to watch out for the symptoms:

• Yellowing, wilting foliage
• Thinning on upper crown of the tree
• Small circular or oblong cankers on twigs, branches or tree trunks

Dutch Elm Disease — Cause and Symptoms

As the name suggests, Dutch Elm Disease (DED) can seriously damage elm trees. The spread of DED is seen by native elm bark beetles and European elm bark beetles that carry either Ophiostoma novo-ulmi or O. ulmi fungi. Sometimes this fungal disease is spread to healthy trees through roof grafts of neighboring diseased elm trees.

Symptoms of DED to look out for, especially during summer months when elm bark beetles are most active, include:

• Wilting and yellowing leaves
• Brown-colored bands or streaks in the outer rings of sapwood

Although leaves are an indicator of Dutch Elm Disease, an official diagnosis can be hard to determine based on foliage alone. Other environmental stressors, such as drought, can cause yellowing leaves on elm trees that don’t necessarily indicate fungus damage. Since there are so many reasons for why an elm tree’s leaves may begin to yellow or wilt, it’s important to consult a plant health care professional that can properly identify the issue and provide the right solution.

Common Bacterial Infections That Damage Trees and Plants

Bacterial Wetwood — Cause and Symptoms

While Bacterial Wetwood isn’t always an urgent or serious case, it is still considered a chronic disease that can eventually damage your trees and plants over time if not managed.

Caused by several strains of bacteria, trees that are infected will show the following symptoms:

• Visible, dark brown-black water “bleeding” from the trunk and branches
• Bubbling or seepage on heavily affected wood tissue

Unfortunately, there is no cure of preventative treatment to avoid Bacterial Wetwood. However, with the help of integrated plant and disease management professionals, the lifespan of trees affected by this bacterial damage can be prolonged.

Elm Yellows — Cause and Symptoms

Elm yellows, caused by phlegm-obligate bacteria, is one of the most destructive diseases of elm trees. This bacteria is typically transmitted by insects like leaf hoppers during the summer and fall months.

If you have an elm tree, you should keep an eye out for yellowing and wilting leaves, along with branch flagging. The symptoms of Elm Yellows are very similar to those of Dutch Elm Disease, so it’s imperative to properly identify the infection before managing or remedying the tree.

Tips to Prevent Fungal and Bacterial Infections

It’s always better to prevent an issue than trying to fix a problem that already exists. If you want to prevent these common fungal and bacterial diseases from forming on your landscape, you may want to:

1. Water plants early in the morning. That way, there’s adequate time for leaves to dry off before nightfall.
2. Prune plants regularly to promote proper air circulation. Without good airflow, plants are at a greater risk of developing fungal or bacterial infections.
3. Invest in Integrated Plant and Disease Management to monitor your trees, shrubs and plants throughout the year. It’s similar to getting check-ups at the doctor’s office to maintain good health and prevent major illnesses.

What to Do if You Suspect Harmful Fungus or Bacteria

Of course, even if you’re diligent, you may still end up being faced with fungal or bacterial growth on your trees and plants. If you notice any of the symptoms mentioned above on your trees or plants — or anything else out of the ordinary — you should reach out to a plant health care professional that can accurately identify the issue and recommend the best course of action.

While it may be tempting to experiment with at-home remedies, you may be putting your trees and plants at risk of reaching a point of no return, or to a point where the solution becomes more costly because of the additional damage incurred.

The experts at Townsend Residential will be able to recommend remedies and develop a plan of action to help your trees and plants thrive.