How to Recognize and Treat Fungus on Trees During the Wet Season

The wet season in the Bay Area creates the perfect conditions for fungal growth on trees, posing risks to their health and stability. Left untreated, fungus on trees can weaken their structure, invite pests, and even lead to tree death. Identifying early signs of fungal infections is essential for preserving your trees and preventing the spread of disease.

In this blog, we’ll explore common types of tree fungi, how to recognize them, and the best treatment options to keep your landscape thriving through the rainy season.

Common Types of Fungus on Trees in the Wet Season

The Bay Area’s wet season brings a surge in fungal activity, with certain types being particularly harmful to trees. Understanding these fungi can help you spot issues early and take action.

1. Powdery Mildew

This fungus appears as a white, powdery coating on leaves, stems, or branches. While it may not kill a tree outright, it can weaken it by reducing photosynthesis and overall health.

2. Armillaria (Root Rot)

Also known as honey fungus, Armillaria attacks tree roots, causing decay and instability. Signs include wilting leaves, dieback, and honey-colored mushrooms near the base of the tree.

3. Anthracnose

Anthracnose thrives in damp conditions and causes irregular brown or black spots on leaves. It can lead to leaf drop and weaken the tree over time.

4. Black Knot

This fungus is easily recognizable by the black, swollen growths it forms on branches. Left untreated, it can stunt growth and eventually kill affected branches.

5. Shelf Fungi (Bracket Fungi)

These wood-decaying fungi grow in shelf-like structures on trunks or branches, often indicating internal decay. They weaken the tree’s structure and increase the risk of breakage.

By familiarizing yourself with these common fungi, you’ll be better equipped to spot infections early. In the next section, we’ll cover the key symptoms of fungus on trees and what to watch for during inspections.

How to Spot Fungus on Trees: Key Symptoms

Early detection is critical when it comes to managing fungus on trees. Regularly inspecting your trees, especially during the wet season, can help you identify potential problems before they escalate. Here are the key symptoms to look for:

1. Discolored or Spotted Leaves

Fungal infections often manifest as unusual discoloration, brown or black spots, or blotches on leaves. Premature leaf drop can also be a warning sign.

2. Mushroom Growth

Fungi like Armillaria or shelf fungi produce visible fruiting bodies, such as mushrooms or bracket-like structures, near the base or on the trunk of the tree.

3. Unusual Bark Changes

Look for peeling, cracking, or discolored bark. Fungal infections can cause cankers—sunken, dead patches on the trunk or branches.

4. Growths or Swellings

Some fungi, like black knot, cause abnormal growths or swellings on branches, which can weaken and deform them over time.

5. Wilting or Dieback

Wilting leaves, branch dieback, or thinning foliage can indicate root or vascular system infections caused by fungi.

6. Soft or Decayed Wood

If parts of the trunk or branches feel soft or appear hollow, fungi may have caused internal decay, weakening the tree’s structure.

7. Odd Odors

A musty or rotting smell around the tree can signal fungal activity, especially if accompanied by visible signs of decay.

If you spot any of these symptoms, it’s important to act quickly. In the next section, we’ll discuss how to treat fungal infections and protect your trees during the wet season.

How to Treat Fungus on Trees During the Wet Season

Treating fungus on trees promptly can prevent further damage and help restore the health of your trees. Here are the steps to take if you suspect a fungal infection:

1. Identify the Issue

Correct treatment starts with identifying the type of fungus affecting your tree. Consult a certified arborist for a professional diagnosis, as some fungi require specific solutions.

2. Prune Infected Areas

Carefully remove infected branches, leaves, or other affected parts of the tree using clean, sterilized pruning tools – it may be best to hire experienced professionals for tree pruning. This prevents the fungus from spreading further. Always dispose of the debris away from healthy plants.

3. Improve Drainage

Excess moisture contributes to fungal growth. If water pools around your tree, consider aerating the soil, creating drainage channels, or adding mulch to help regulate moisture levels.

4. Enhance Airflow

Trim nearby shrubs or branches that crowd the tree to improve air circulation. Better airflow reduces the damp conditions fungi thrive in.

5. Boost Tree Health

Healthy trees are more resilient to infections. Regular watering (without overwatering), proper fertilization, and mulching can strengthen your tree’s natural defenses.

7. Call an Arborist for Severe Cases

If the infection is widespread or affecting the tree’s structural integrity, call a certified arborist. They can assess whether the tree can be saved and implement advanced treatments, such as trunk injections or systemic fungicides.

Treating fungal infections promptly not only saves the tree but also prevents the spread to other plants in your landscape.

Keep Your Trees Healthy This Wet Season

Fungal infections can pose serious risks to trees during the wet season, but with prompt action and proper care, you can protect your landscape and ensure your trees stay healthy. From identifying early signs to implementing effective treatments, addressing fungus on trees quickly makes all the difference.

At Sexy Trees, we’re experts in diagnosing and treating tree fungus. Whether you need professional advice, pruning, or advanced care, our certified arborists are here to help. Contact us today to keep your trees thriving, rain or shine!