Identify Tree Fungus For Wood Processing (5 Expert Signs)

The Best Option: Early Fungus Identification for Optimal Wood Use

As someone who’s spent decades in the wood processing and firewood preparation industry, I’ve learned that one of the most critical skills is identifying tree fungus before you even think about felling a tree or processing logs. Why? Because early detection can save you time, money, and a whole lot of frustration. Knowing how to spot fungal infections allows you to make informed decisions about whether a tree is suitable for lumber, firewood, or should simply be left to decompose in the forest. It’s about making the best use of available resources, minimizing waste, and ensuring the safety of yourself and others. It’s the difference between a valuable resource and a costly problem.

1. Visible Fruiting Bodies (Mushrooms, Conks, Brackets)

This is the most obvious sign, but it’s crucial to understand what you’re looking at. These “fruiting bodies” are the reproductive structures of the fungus, like the flowers of a plant. Their presence always indicates that the fungus is already well-established inside the tree.

Mushrooms: These are often short-lived, appearing after rain. While some are harmless, many indicate significant decay. For example, clusters of Armillaria mushrooms near the base of a tree are a sign of root rot, which can weaken the entire tree. I once had a beautiful oak tree that seemed perfectly healthy until a heavy rain revealed a ring of Armillaria around its base. Within a year, it had to be taken down due to its instability.
Conks (Shelf Fungi): These are the hard, woody or leathery growths that protrude from the trunk. They can be annual (lasting only one season) or perennial (growing larger each year). Perennial conks are particularly concerning, as they demonstrate a long-term, active fungal infection. Ganoderma applanatum (Artist’s Conk) is a common example.
Brackets: Similar to conks, but often smaller and more delicate. They can come in a variety of shapes, sizes, and colors. Trametes versicolor (Turkey Tail) is a visually striking bracket fungus that is often found on dead or decaying wood, but its presence on a living tree should raise concerns.

What to look for:

Location: Are the fruiting bodies near the base, on the trunk, or on branches? This can give you clues about where the decay is concentrated.
Type: Different fungi cause different types of decay. Knowing the species of fungus can help you predict the extent and type of damage.
Size and Condition: A large, well-established fruiting body suggests a more advanced infection.

My experience: I recall a job where a client wanted me to mill a large maple tree into lumber. The tree looked healthy from a distance, but upon closer inspection, I noticed a small Ganoderma conk near the base. I advised the client to have the tree assessed by an arborist. Sure enough, the arborist confirmed extensive heart rot, making the tree unsuitable for milling. We ended up using it for firewood, but the client was grateful we caught it before wasting time and resources on milling unusable wood.

2. Bark Abnormalities

The bark is the tree’s protective layer, and changes in its appearance can signal underlying problems.

Cankers: These are sunken, dead areas of bark, often surrounded by a raised callus. They are usually caused by fungal infections that kill the cambium (the layer of cells that produces new wood and bark). Cankers can weaken the tree and make it susceptible to breakage.
Discoloration: Patches of discolored bark, especially if they are soft or spongy, can indicate decay.
Cracks and Splits: Deep cracks and splits in the bark can be entry points for fungi. They can also be a sign that the tree is under stress.
Exudates (Seepage): Oozing sap or other liquids from the bark can be a sign of infection.

What to look for:

Size and Shape of Cankers: Larger cankers are more serious. Cankers that encircle the trunk can be fatal.
Location of Bark Abnormalities: Cankers near the base of the tree are often more serious than those higher up.
Presence of Insects: Insects are often attracted to weakened or decaying trees, so their presence can be an indirect sign of fungal infection.

My experience: I was once asked to remove a large ash tree that had several large cankers on its trunk. The homeowner was concerned that the tree was a hazard. When I cut into the tree, I found that the cankers had penetrated deep into the heartwood, leaving the interior riddled with decay. The tree was indeed a hazard and needed to be removed.

3. Changes in Crown Condition

The crown (the upper part of the tree, including the branches and leaves) is a good indicator of overall tree health. Changes in the crown can be early warning signs of fungal infection.

Dieback: This is the progressive death of branches from the tips inward. It can be caused by a variety of factors, including fungal infections that disrupt the flow of water and nutrients to the branches.
Thinning Canopy: A sparse or thinning canopy, where you can see more sky through the leaves than usual, can indicate that the tree is under stress.
Premature Leaf Drop: If the tree is losing leaves earlier than normal, it could be a sign of infection.
Discolored or Distorted Leaves: Fungal infections can cause leaves to develop spots, blotches, or other abnormalities.

What to look for:

Pattern of Dieback: Is the dieback concentrated in one area of the crown, or is it widespread?
Severity of Thinning: How much of the canopy is affected?
Timing of Leaf Drop: Is the leaf drop occurring significantly earlier than normal?

My experience: I was assessing a stand of birch trees for firewood harvesting when I noticed that several of the trees had significant dieback in their crowns. Upon closer inspection, I found evidence of Nectria canker, a fungal disease that commonly affects birch trees. I decided to avoid harvesting those trees, as the wood was likely to be of poor quality.

4. Woodpecker Activity

While woodpeckers are beneficial birds, their presence can also indicate problems with a tree. Woodpeckers often target trees that are infested with insects or have internal decay.

Extensive Drilling: If you see a lot of woodpecker holes in a tree, it’s a sign that they are finding something to eat. This could be insects that are feeding on decaying wood.
Fresh Wood Chips: The presence of fresh wood chips at the base of a tree can indicate recent woodpecker activity.

What to look for:

Location of Woodpecker Holes: Are the holes concentrated in one area of the tree, or are they scattered throughout the trunk and branches?
Type of Woodpecker: Different woodpeckers have different feeding habits. Some target insects, while others feed on sap.

My experience: I was once felling a large oak tree that had a few woodpecker holes in its trunk. When I cut the tree open, I discovered that the interior was riddled with insect tunnels and decay. The woodpeckers had been attracted to the insects that were feeding on the decaying wood.

5. Soil Conditions and Root Health

The health of the soil and the tree’s root system are critical to its overall well-being. Problems with the roots can make the tree more susceptible to fungal infections.

Standing Water: Trees that are growing in poorly drained soil are more likely to develop root rot.
Compacted Soil: Compacted soil can restrict root growth and make the tree more vulnerable to stress.
Damaged Roots: Construction activities, landscaping, or even lawnmowers can damage tree roots, creating entry points for fungi.
Presence of Root-Rot Fungi: Some fungi, such as Armillaria, directly attack the roots of trees.

What to look for:

Drainage: Does the water drain away quickly after a rain, or does it pool around the base of the tree?
Soil Compaction: Is the soil hard and difficult to dig?
Exposed Roots: Are any of the tree’s roots exposed? If so, are they damaged or decaying?

My experience: I was consulted about a large spruce tree that was declining rapidly. The homeowner had recently installed a new patio, and the construction crew had inadvertently damaged several of the tree’s roots. This had created entry points for fungi, leading to root rot and the tree’s eventual demise.

Understanding Decay Types and Their Impact

Identifying the type of decay is just as crucial as recognizing the presence of fungus. Different fungi cause different types of decay, each with its own implications for wood processing. Here’s a breakdown of the most common types:

Brown Rot: This type of decay primarily attacks the cellulose in wood, leaving behind a brown, crumbly residue. Wood affected by brown rot loses its strength rapidly and is unsuitable for lumber. It’s often caused by fungi like Serpula lacrymans (Dry Rot) and Gloeophyllum sepiarium. Firewood affected by brown rot will burn quickly and produce less heat.
White Rot: White rot fungi break down both cellulose and lignin in wood, leaving behind a bleached, stringy, or spongy residue. The color can vary, but it’s often lighter than the original wood. Trametes versicolor (Turkey Tail) and Ganoderma species are common culprits. While white rot can weaken wood, it doesn’t always cause it to crumble like brown rot. In some cases, wood affected by white rot can still be used for certain purposes, like rustic furniture.
Soft Rot: This type of decay is caused by fungi that can tolerate very wet conditions. It’s often found in wood that is in contact with the soil or constantly exposed to moisture. Soft rot creates small cavities within the wood cells, weakening the wood over time. It’s less common in standing trees but can be a problem in stored logs or firewood.
Heart Rot: This is a type of decay that affects the heartwood (the non-living core of the tree). Heart rot fungi enter the tree through wounds or branch stubs and gradually decay the heartwood, leaving the sapwood (the living outer layer) intact. Trees with heart rot can appear healthy from the outside, but the internal decay can significantly weaken them. Many of the fungi mentioned above can cause heart rot.

Impact on Wood Processing:

Lumber: Wood with significant decay of any type is generally unsuitable for lumber. The decay will weaken the wood and make it prone to cracking and warping.
Firewood: Wood with brown rot is still usable for firewood, but it will burn quickly and produce less heat. Wood with white rot may be more difficult to split and burn. Wood with soft rot is generally not recommended for firewood, as it may be too wet and difficult to ignite.
Other Uses: In some cases, wood with minor decay can be used for rustic furniture, wood turning, or other decorative purposes. However, it’s important to carefully assess the extent and type of decay before using the wood.

My experience: I once purchased a load of firewood that was advertised as “seasoned oak.” However, when I started splitting the wood, I found that many of the logs were affected by white rot. The wood was soft and spongy, and it was difficult to split. I ended up having to discard a significant portion of the load. This experience taught me the importance of carefully inspecting firewood before buying it.

Tools and Techniques for Assessing Tree Health

While visual inspection is crucial, sometimes you need to use tools and techniques to get a more accurate assessment of a tree’s internal condition.

Increment Borer: This is a specialized tool that allows you to extract a core sample from a tree without harming it. The core sample can be examined to assess the tree’s age, growth rate, and internal condition. I use a 12″ increment borer, which is suitable for most trees I encounter. The core sample can reveal signs of decay, such as discoloration, soft spots, or fungal hyphae.
Resistograph: This is a more advanced tool that measures the resistance of the wood to penetration. It can be used to detect internal decay and cavities. Resistographs are more expensive than increment borers, but they provide a more detailed assessment of the tree’s internal condition.
Sounding: This involves tapping the trunk of the tree with a hammer or mallet and listening to the sound. A solid, resonant sound indicates healthy wood, while a dull, hollow sound suggests decay. This technique takes practice to master, but it can be a quick and easy way to identify potential problems.
Visual Inspection from a Height: Using binoculars or climbing the tree (if you are trained and equipped to do so safely) can allow you to get a better view of the crown and upper branches. This can help you spot signs of dieback, thinning, or other abnormalities that may not be visible from the ground.

Safety Considerations:

Personal Protective Equipment (PPE): Always wear appropriate PPE when working with trees, including a hard hat, safety glasses, gloves, and sturdy boots.
Working at Heights: If you need to climb a tree to assess its health, be sure to use proper climbing techniques and equipment. If you are not trained and experienced in tree climbing, it’s best to hire a professional arborist.
Hazard Trees: Be aware of the potential hazards associated with working around trees, such as falling branches or unstable trunks. If you suspect that a tree is unstable, do not attempt to climb it or work near it.

My experience: I once used an increment borer to assess a large oak tree that was suspected of having heart rot. The tree appeared healthy from the outside, but the homeowner was concerned because a large branch had recently fallen. The core sample revealed extensive decay in the heartwood, confirming the homeowner’s suspicions. We advised the homeowner to have the tree removed, as it was a hazard.

Strategic Decision-Making Based on Fungus Identification

The ultimate goal of identifying tree fungus is to make informed decisions about how to use the wood. Here’s a framework for strategic decision-making:

Assess the Extent and Type of Decay: Use the techniques described above to determine the extent and type of decay.
Consider the Intended Use: What do you want to use the wood for? Lumber, firewood, or something else?
Evaluate the Structural Integrity: Is the wood strong enough for its intended use?
Weigh the Risks and Benefits: What are the risks of using the wood, and what are the benefits?
Make a Decision: Based on your assessment, decide whether to use the wood, discard it, or leave the tree standing.

Specific Scenarios:

Lumber: If the wood has significant decay, it’s generally unsuitable for lumber. Even if the decay is localized, it can weaken the wood and make it prone to cracking and warping.
Firewood: Wood with brown rot is usable for firewood, but it will burn quickly and produce less heat. Wood with white rot may be more difficult to split and burn. Wood with soft rot is generally not recommended for firewood.
Rustic Furniture: Wood with minor decay can be used for rustic furniture, but it’s important to carefully assess the extent and type of decay.
Wood Turning: Wood with interesting patterns of decay can be used for wood turning, but the wood may be more difficult to work with.
Leaving the Tree Standing: In some cases, it may be best to leave the tree standing. This is especially true if the tree is providing habitat for wildlife or if it is located in a sensitive area. However, it’s important to assess the risk of the tree falling and causing damage or injury.

Case Study: Optimizing Firewood Production from a Diseased Ash Tree

I was contacted by a homeowner who had a large ash tree that was showing signs of ash dieback, a fungal disease that is devastating ash populations across Europe and North America. The tree had significant dieback in its crown, and there were several cankers on its trunk. The homeowner wanted to know if the tree was suitable for firewood.

I assessed the tree using the techniques described above. I found that the tree had extensive dieback in its crown and several large cankers on its trunk. I also found evidence of heart rot in the lower trunk.

Based on my assessment, I determined that the tree was not suitable for lumber. However, I concluded that the sounder portions of the trunk could be used for firewood. I advised the homeowner to fell the tree and cut it into firewood-sized pieces. I also advised him to carefully inspect each piece of wood for signs of decay and to discard any pieces that were significantly affected.

The homeowner followed my advice, and he was able to produce a significant amount of firewood from the tree. He was also able to remove a hazardous tree from his property.

Tools used:

Chainsaw: Stihl MS 261 C-M (a versatile saw suitable for felling and bucking).
Splitting Axe: Gransfors Bruks Splitting Axe (known for its efficiency and durability).
Wedges: Steel felling wedges (to prevent the tree from pinching the saw during felling).

Safety Precautions:

Wore appropriate PPE, including a hard hat, safety glasses, gloves, and chaps.
Felled the tree in a safe direction, away from buildings and power lines.
Used proper felling techniques to avoid kickback and other hazards.

Results:

The homeowner produced approximately 3 cords of firewood from the tree.
The firewood was seasoned for one year before being burned.
The homeowner was able to heat his home for several months using the firewood.

Drying and Storing Firewood to Minimize Further Decay

Even after you’ve identified and processed wood for firewood, proper drying and storage are essential to prevent further fungal growth and decay.

Seasoning: Seasoning is the process of drying firewood to reduce its moisture content. Green wood (freshly cut wood) can have a moisture content of 50% or more, while seasoned wood should have a moisture content of 20% or less. Seasoning firewood makes it easier to ignite, burn more efficiently, and produce less smoke.
Stacking: Stack firewood in a single row, off the ground, in a sunny and windy location. This will allow air to circulate around the wood and speed up the drying process. I recommend using pallets or cinder blocks to elevate the wood off the ground.
Covering: Cover the top of the firewood pile with a tarp or other waterproof material to protect it from rain and snow. However, leave the sides of the pile open to allow for air circulation.
Storage: Store seasoned firewood in a dry, well-ventilated location. A woodshed or garage is ideal. Avoid storing firewood directly on the ground or against a wall, as this can trap moisture and promote decay.

Timing:

Drying Time: The amount of time it takes to season firewood depends on the type of wood, the climate, and the stacking method. Hardwoods, such as oak and maple, typically take 6-12 months to season. Softwoods, such as pine and fir, can season in as little as 3-6 months.
Moisture Meter: Use a moisture meter to check the moisture content of the firewood. A moisture meter is a small, handheld device that measures the electrical resistance of the wood. The lower the resistance, the lower the moisture content.

My experience: I once stored a large pile of firewood directly on the ground, thinking that it would be protected from the rain. However, the wood absorbed moisture from the ground, and it quickly began to rot. I learned my lesson and now always stack firewood off the ground and cover it with a tarp.

Conclusion: A Holistic Approach to Wood Processing

Identifying tree fungus is a critical skill for anyone involved in wood processing or firewood preparation. By learning to recognize the signs of fungal infection, you can make informed decisions about how to use the wood, minimize waste, and ensure the safety of yourself and others. Remember to consider the type and extent of decay, the intended use of the wood, and the overall health of the tree. Use the tools and techniques described above to assess the tree’s condition, and always prioritize safety. And finally, don’t underestimate the importance of proper drying and storage to prevent further decay. By taking a holistic approach to wood processing, you can maximize the value of your resources and enjoy the fruits of your labor for years to come.

Identify Tree Fungus for Wood Processing (5 Expert Signs)