What Kinds of Fungi Decay Arbutus Trees and Why Is My Pacific Madrone Dying?

Is your Madrone tree not at its best? Are you asking yourself, “What kinds of fungi decay Arbutus trees and why is my Pacific Madrone dying?” In this article, we’ll dig deep to find the answers you’ve been looking for.

Named after its discoverer, Arbutus menziesii is a native North American ornamental tree. It’s also known as Arbutus, Pacific Madrone, and Madrona. The plant is heavy with extremely hard-to-chop wood that tends to warp after drying. It produces fruits that serve as food for birds and some wild animals.

This article will tackle Madrone diseases and attempt to discuss solutions for healthier Madrone.

Madrone Diseases

There are around three main areas that diseases prey on when it comes to Arbutus trees. 

Most diseases prey on three main areas in Arbutus trees. Some affect the leaves, while others might attack the branches or the roots. The cause of the damage may vary from fungi to canker diseases.

Foliage Diseases

In this section, you’ll know how to diagnose Madrone foliage sickness, what causes it, and what to do if your Pacific Madrone is dying.

What Do They Look Like?

Some foliage diseases appear as hollowed spots on leaves. The spots vary in their diameter from 0.25 to 0.5 inches. These fungal spores are characterized by their circular or irregular form. Some spores might consume large areas from the leaves, while others might keep the same circumference.

They’re typically brownish, but some spots may have small yellowish margins. Unfortunately, the spots might coalesce to destroy the whole leaf.

What’s Their Effect on Madrone?

Despite the seemingly grave outcome of foliage destruction, these spots aren’t threatening. They mainly cause discomfort when it comes to how aesthetically pleasing the tree looks. 

What Causes Them?

It’s quite tough to decipher the real secret behind sick foliage. Yet, researchers think that fungi are the main culprit. Fungal organisms travel via water drops from a leaf to another, which causes airborne disease transmission.

Phytophthora ramorum fungus, commonly known as sudden oak death, tears up the Madrone surface and spreads deadly spores on top of its leaves. On the backside of the leaves, however, a common fungus chemically known as Rhytisma acerinum might cause brown or black irregular spots. 

What Should You Do?

As we said earlier, there’s no need to panic about Madrone foliage diseases because they’re not fatal. However, you can reduce the spread of the fungi infection by pruning dead leaves and branches.

Trimming excess foliage can help in reducing shade and increasing light all over the plant, which will eventually boost the Madrone’s health.

Twigs and Branches Diseases

Here, we’ll discover what causes the dieback of twigs, branches, and trunks. You’ll get to know the symptoms of canker fungi and how to deal with all of these diseases.

What Causes Them?

There are two common reasons for such chaos. First, fungal infections. Fungi are mostly fatal, especially when they infect the cambium—the active growth layer of Madrone. They mainly attack vulnerable trees through wounded tissues.

Second, the misuse of yard equipment. So, yeah, you may have been injuring your Madrone without knowing. Be cautious with lawnmowers around a tree trunk because there’s a chance you might aggressively scratch or cut the trunk open. 

Ultimately, scratched areas die and get replaced by cankers—a pretty deadly fungus. Cankers make themselves at home, inviting other pathogens that your plant won’t feel welcome around.

What Do They Look Like?

When you see a change of color in Madrone, it’s probably a fungal infection. Fungi change the color of bark from natural, beautiful green to blackened, almost burnt brown. 

On the other hand, to know a dieback disease, notice the slow but steady drying process. Twigs color won’t change all of a sudden, but they’ll gradually lose their vitality. The dieback starts from the tips of the branches and progresses downwards until the destruction is accomplished.

What Should You Do?

First, limit mechanical injuries as much as possible to decrease the chances of vulnerable regions where canker can inhabit. 

Second, deeply water the plant from time to time to prevent drought: Your tree needs to have enough supply of nutrients to fight those diseases.

Third, keep a schedule of proper pruning to disrupt wood decay.

Root Diseases

Visible dieback is probably the reason you started worrying about your Madrone trees. However, the cause might literally be entrenched deep down in the roots. Unfortunately, the vicious effect of dieback disease doesn’t stop at the roots, but can also hit the tree trunk.

What Do They Look Like?

A root disease would appear as brown infection or black decay in the trunk. You might as well suspect a problem with the roots when you notice the tree sap oozing out as discolored discharge. 

What Causes Them?

Both humans and nature can overburden Madrone’s roots and put the whole plant in danger. Something that we unconsciously do that hurts plants is excessive watering. You might feel the urge to give the plant all you can, but this should not necessarily include water. 

Over irrigation is a huge deal when it comes to many plants for a reason. Soggy soil is a perfect habitat for fungi, especially Armillaria. So, don’t be generous by watering the plant more than what it actually needs.

What Should You Do?

Avoid overwatering the plant for a better overall healthy Madrone. Some trees will persevere despite the stress, but it’s easier to spare your tree and avoid such exhaustion. 

On the contrary, deep watering every two weeks can enhance trees’ vigor and ability to sustain themselves during hot summer waves.

Madrone Insect Pests

Insects don’t necessarily put Madrone’s life in danger. Yet, there’re some pests and worms that contribute to the slow but steady downfall of certain parts of the plant. For instance, aphids, fall webworms (Hyphantria cunea), and western tent caterpillars can feed on the trees’ fruits and sap.

You can control a pest infection by pruning foliage. Also, to get rid of Aphids, try knocking them off with a water hose. Pay extra attention not to destroy the leaves, though.

Keeping Madrone Healthy

Cultural control can have a significant impact on the recovery process of sick Madrone. Awareness is a key factor to save your plant before it’s too late. Try to learn more about your plant to understand its features and characteristics. You might also want to pay a visit to your local plant disease control center for a consultation.

Always try to make sure that Madrone has enough sunlight. Airy, will-lit surroundings help the plant become more resilient and vigorous. On the other hand, partially shaded foliage is more likely to be sick and diseased because they aren’t able to photosynthesize as they need. To solve the equation and achieve the perfect atmosphere, consider regular pruning.

After pruning a tree, disinfect your tools before using them on another tree to minimize the risk of cross-infection. Although some people use bleach for this task, you can use a simple mouthwash to stay away from harsh chemicals. 

Avoid excessive or inadequate irrigation and seek a balance between both. While watering, direct the stream right at the root zone and away from the trunk. A sign of an overwatered soil would be dampness for a couple of days. Stick your finger about two inches down the soil; if it comes back with pits and pieces of wet soil all over it, then there’s extra moisture.

The Takeaway

Many diseases can sicken your Arbutus tree. Foliage diseases can devour the leaves, trunk dieback and cankers might sever the branches, and fungi can strike roots.

Overall, you can defeat most of these diseases by regular irrigation, sunlight exposure, limiting mechanical injuries, and consistent pruning.

Wishing you a happy, evergreen Madrone tree!