Fungi are an essential part of our ecosystem, contributing to the recycling of nutrients and organic matter. However, some fungi can also be harmful, especially when they attack trees. Identifying common tree fungi and understanding treatment options is key for effective tree care and landscape management.

Signs and Symptoms of Tree Fungus

There are a few key signs that may indicate a tree is affected by a fungus:

Mushrooms or Conks

One of the most obvious signs of fungus is the presence of mushrooms or conks growing directly on the tree trunk or branches. These reproductive structures produce and release spores. Different fungus species produce different mushroom shapes, sizes, and colors.

Common examples include:

• Shelf or bracket fungi that grow in layered, shelf-like caps on trunks.
• Mushrooms with central stalks and caps growing from roots below ground or woody debris around the base.
• Ball-shaped puffball mushrooms that release powdery spores when pressed or burst open naturally.

Fruiting Bodies and Spore Masses

Some fungi produce small, round fruiting bodies that rupture to release spores. Tiny black pinhead-like pycnidia or larger perithecia may dot infected bark. Powdery masses of orange, yellow, or other colored spores can also erupt from bark.

Mycelium Fans

Mycelium refers to the vegetative network of threadlike hyphae that make up the main body of fungi. White or brightly colored mycelium fans may visibly grow between bark and wood. Mycelium secretes enzymes that break down plant tissue.

Bleeding Cankers

Fungal cankers damage the vascular cambium, interrupting the flow of water and nutrients. Cankers often ooze sap, which appears as wet spots or streaks on bark. Dark sunken lesions may also signal cankers.

Dieback

Fungal infections can cause entire branches or even whole trees to die back from the tips inward. Dead twigs and small branches with withered brown leaves are a symptom.

Rotting Wood

Wood decay fungi break down lignin and cellulose, causing wood to crumble. Advanced fungal rot may cause swollen cankers, hollowed trunks, or a spongy texture in infected wood.

Common Tree Fungi

There are thousands of fungi that can grow on trees, but a few groups account for most landscape infections:

Wood and Butt Rot Fungi

Fungi like Ganoderma, Armillaria, Laetiporus, and Phellinus species cause wood and butt rots. Heart rot fungi slowly degrade heartwood, while butt rot fungi infect the tree base and roots. Infected trees are prone to blowing over in high winds.

Canker and Wilt Fungi

Botryosphaeria, Cryptodiaporthe, Neofusicoccum, Ceratocystis, and Verticillium fungi lead to branch dieback and sometimes full wilt. Canker fungi kill patches of bark and cambium while vascular wilt fungi clog water-conducting cells.

Rust Fungi

Coleosporium, Cronartium, Gymnosporangium, Melampsora, and Puccinia rust fungi trigger orange, yellow, brown, or white leaf spots. Severe rust can negatively impact tree growth and vigor.

Leaf Blight/Spot Fungi

Anthracnose, leaf spot, and blight fungi like Apiognomonia, Discula, Guignardia, Entomosporium, and Septoria create spots, patches, or curled areas on leaves and needles. Defoliation can occur.

Root and Butt Rot Fungi

Armillaria, Ganoderma, Heterobasidion, Phytophthora, and other soil-borne fungi infect roots, typically entering through wounds. Aboveground symptoms include thinning canopy, slow growth, and eventual death.

Powdery Mildew Fungi

Superficial fungal diseases like powdery mildew coat leaves, needles, shoots, and flowers in white fungal growth. Common examples are Erysiphe, Microsphaera, Phyllactinia, and Podosphaera. Severe cases Impact photosynthesis.

Fungus Identification

Proper identification is important to select appropriate treatment methods. Consider characteristics like:

• Mushroom shape, texture, color
• Location on tree
• Host tree affected
• Pattern of symptoms like canker margins, leaf spots, etc.
• Signs like mycelium, spore masses, etc.

Take high quality photos of symptoms, surrounding environment, and fruiting structures. Microscopic analysis of spores may help pin down a diagnosis. Submit samples to diagnostic labs for culture and DNA testing if needed. Compare findings against published guides and expert knowledge.

Some fungi can be tentatively diagnosed based on recognizable symptoms. For example, Ganoderma species often form dramatic shelf mushrooms on trunks:

Credit: Gardening Know How

However, many tree fungi can only be identified by lab analysis. For instance, related Cytospora, Valsa, Leucostoma, and Valsella species cause very similar cankers, dieback, and staining, requiring microscopy or lab culture to differentiate.

Tree Fungus Treatment and Management

Effective Integrated Pest Management utilizes a combination of cultural, biological, and chemical measures:

Sanitation

• Prune out dead branches, water sprouts, and other debris.
• Rake up fallen leaves and twigs. Compost or remove this debris.
• Avoid excessive mulch buildup around tree bases.
• Disinfect tools between trees to avoid transmission.

Wound Care

• Prune properly in early dormancy and avoid unnecessary wounds.
• Trim damaged roots and smooth ragged bark edges.
• Promote compartmentalization of infections via stimulation methods.

Air Circulation and Sunlight

• Space trees appropriately to encourage air flow.
• Thin dense interior canopy branches to increase light penetration.

Watering

• Water trees during drought stress to maintain vigor.
• Improve drainage in poorly aerated or compacted soils.
• Mulch around trees to conserve soil moisture and reduce soil compaction.

Fertilization

• Apply balanced fertilizer in early spring to support tree health.
• Avoid excess nitrogen, which promotes susceptible fast shoot growth.

Pest Management

• Monitor for and manage secondary insect and disease problems like borers, canker worms, etc.

Fungicides

• Apply preventative labeled fungicides around infection periods for protection.
• Use systemic fungicides for eradicant activity against existing infections.
• Always follow label directions for allowed sites, rates, timing, and required PPE.

Biological Control

• Research potential biofungicides like Trichoderma species for suppression of some soil fungi.

Tree Removal

• Remove and destroy trees with severe advanced infections to prevent further spread.

An integrated program should focus on promoting plant health and managing wounds to avoid infections. When fungal diseases do strike, sanitation, fungicides, and biocontrols can help suppress spread and severity. Seek professional diagnosis and management assistance for valuable landscape trees. Stay vigilant for symptoms and signs to detect fungal problems at an early and most treatable stage.

Frequently Asked Questions About Tree Fungi

Tree fungi are complex organisms intertwined with forest, landscape, and human health. Here are answers to some common questions about identification and control of tree fungi:

What are some key differences between molds, mushrooms, and other fungal types?

• Molds are filamentous fungi that grow as cottony or powdery colonies on plant or animal matter.
• Mushrooms are the reproductive structures of some fungi that have a fleshy cap on a stalk rising above ground.
• Rusts, mildews, rots, and blights are damaging plant diseases caused by more complex fungal organisms.
• Yeasts are single-celled spherical fungi like Candida albicans. They reproduce by budding off daughter cells.
• Mycorrhizal fungi form symbiotic relationships with plant roots to aid nutrient uptake.

How can you tell if a mushroom is edible or poisonous?

There is no simple home test to determine edibility. Never eat any wild mushroom unless you have had it positively identified by an expert mycologist. Some tips:

• Avoid any mushrooms with white gills, a skirt or ring on the stem, or a volva cup at the base. These suggest the deadly Amanita genus.
• Look for blue, black or orange bruising which indicates toxicity. Smell for phenol or carbolic acid odors.
• Start learning edibles with easily recognized, choice species like chicken of the woods or morels.

Do tree fungi play any beneficial roles?

Yes, many fungi break down wood and leaf litter, releasing bound nutrients. Edible mushrooms like oyster, chanterelle, and maitake have culinary and potential health benefits. Medicinal fungi contain antimicrobial compounds. Mycorrhizae aid plant growth.

Should you remove brackets, conks, or mushrooms growing on a living tree?

Scrape off any shelving fruiting fungal structures. Remove sporocarps or conks by cutting off flush with the bark surface. Avoid pulling them off, which strips even more bark. Sterilize tools between cuts.

How do you treat lawn mushrooms?

Mow over mushroom caps before they release spores. Improve drainage and aeration of overly moist soils. Reduce thatch thickness through aerification, raking, or dethatching. Apply compost tea or quality compost to enrich soil microbiome diversity.

What is the best way to manage fungus on landscape trees?

Focus on prevention by selecting resistant species, maintaining tree vigor, and avoiding unnecessary wounds. Promote airflow circulation. Clean up and remove fallen debris promptly. Apply preventative fungicides before infection periods when warranted. Prune out affected branches.

Conclusion

Tree fungi perform vital ecological roles, yet some species can devastate ornamental and forest tree health. Being able to identify common tree fungi by mode of infection, signs and symptoms, and fruiting structures is key to guiding control decisions. An integrated pest management plan using sanitation, cultural practices, biological control agents, targeted fungicide applications, and tree removals if warranted, can help limit fungal impacts. Continue learning about tree fungi identification and management techniques to protect your landscape.

Common Signs, Symptoms, and Treatments

Trees provide beauty, shade, and ecological benefits to landscapes. However, fungi pose one of the most significant threats to tree health. This section will explore common signs and symptoms of fungal infections, as well as various treatment methods to manage tree fungi.

Wilting, Dieback and Decline

Trees rely on an interconnected network of woody tissues just under the bark to transport water, sugars and nutrients up and down the trunk and throughout the branches. When fungi infect and degrade these vascular tissues, known as the xylem and phloem, they interrupt the flow of water and nutrients throughout the tree.

Signs and Symptoms

• Branch dieback – Progressive death of shoots and branches
• General canopy thinning and wilting
• Slowed growth
• Small, off-color leaves
• Early fall coloration and leaf drop

Treatments

• Improve drainage and reduce compaction
• Water during drought stress
• Apply preventative fungicides to protect new growth
• Fertilize to improve vigor
• Prune out severely affected branches
• Remove extensively damaged trees

Cankers

Cankers are areas where fungal infections kill patches of bark and cambium tissues. Cankers often appear as sunken or discolored lesions and can girdle limbs or the whole trunk.

Signs and Symptoms

• Sunken, cracked bark
• Dead branch tips beyond canker
• Discolored sap oozing from margins
• Callus tissue forming at edges

Treatments

• Cut out active cankers and sterilize tools
• Apply wound paints or pruning sealants
• Spray fungicidal coatings on susceptible bark
• Improve air circulation
• Fertilize surrounding tissues to stimulate compartmentalization
• Remove extensively cankered trees

Wood Decay

Wood decay fungi gradually break down lignin, cellulose and other woody compounds. Advanced decay causes structural wood to crumble away.

Signs and Symptoms

• Hollow, cracked trunks
• Mushrooms, conks, or mycelial fans on bark
• Spongy, crumbly wood
• Sagging, leaning trees

Treatments

• Support valuable trees with cables and braces
• Remove prior to toppling in winds
• Keep surrounding grass away from root collar
• Avoid unnecessary wounds
• Apply wood preservative pastes or foams

Root Rot

Soil-borne fungi infect woody roots, typically entering through wounds or stem tissue near the soil line. Infections spread to major buttress and structural roots.

Signs and Symptoms

• Thin canopy with lighter foliage
• Dieback and death of peripheral branches
• Resin bleeding around root collar
• Fruiting bodies near soil line

Treatments

• Remove infected trees to contain spread
• Avoid excessive mulch buildup at base
• Improve drainage in poorly aerated soils
• Apply biofungicides e.g. Trichoderma
• Solarize soil or replace with clean fill before replanting

Leaf Spots and Blights

Many fungi attack leaf and needle tissues directly. Small spots enlarge and merge to form brown blotches. Severe infections defoliate trees.

Signs and Symptoms

• Round leaf spots with dark borders
• Angular yellow leaf blotches
• Black coating on blighted shoots
• Premature leaf drop

Treatments

• Rake and remove fallen leaves promptly
• Apply fungicides at bud break for protection
• Improve air circulation in canopy
• Water in morning so leaves dry completely
• Fertilize appropriately to avoid succulent growth

Rust Diseases

Rust fungi cause yellow, orange, brown or white pustules on leaves. Black teliospores spread repeat infections. Heavily rusted trees weaken and grow poorly.

Signs and Symptoms

• Bright yellow leaf spots
• Raised orange or white spore pustules
• Black overwintering teliospores
• Premature defoliation

Treatments

• Apply fungicides at bud break
• Rake and dispose of fallen leaves with teliospores
• Plant resistant varieties
• Prune off infected branches
• Remove highly susceptible trees

Identification of Common Tree Fungi

Proper identification of tree fungi is essential for effective management. This section covers some of the most common tree fungi found in landscapes and forests based on distinctive field symptoms and microscopic characteristics.

Ganoderma Root and Butt Rot

Host Trees

Hardwoods like oak, maple, elm, willow, and fruit trees

Signs and Symptoms

• Large, hard, woody conks on lower trunk
• White mycelial fans between bark and wood
• Hollow trunk, little healthy wood left

Microscopy

• Double-walled basidiospores
• Clamp connections present

Management

Remove extensively infected trees. Avoid wounds, soil compaction. Improve drainage.

Image Source: Arborilogical Services

Armillaria Root Rot

Host Trees

Broad host range including hardwoods and conifers

Signs & Symptoms

• Clusters of small honey mushrooms at base
• Mycelial fans under bark
• Resin bleeding from lower trunk

Microscopy

• Segmented mycelial strands
• Clusters of oval spores

Management

Remove badly infected trees. Apply fungicidal drenches. Improve drainage.

Image Source: Penn State Extension

Hypoxylon Canker

Host Trees

Mainly oaks, also affects poplar, willow, maple, birch

Signs & Symptoms

• Cankers with black zone lines
• White, pink, orange fungal pustules
• Dieback

Microscopy

• Curved, Y-shaped ascospores
• Asexual state: Libertella with curved conidia

Management

Improve vigor. Prune out cankers. Protect wounds. Remove susceptible trees.

Image Source: Home and Garden Information Center, University of Maryland Extension

Phytophthora Root and Collar Rot

Host Trees

Many broadleaf and conifer species

Signs & Symptoms

• Bleeding lesions on lower trunk