Imagine looking out on your garden and noticing that one of the arborvitaes you planted three years ago – the ones that had just started to block out your annoying neighbors’ loud purple paint job – was looking a little ragged around the edges.
Or taking a stroll in your backyard and seeing a mysterious wilt in that Japanese maple you’ve been caring for over the last 20 years. Or … or …
We care a lot about our yards, and even more about the trees in them. While you can lay down new sod or replace those ailing boxberry bushes without too much trouble, a tree is an investment that takes time to mature. Therefore, when a formerly healthy tree gets attacked by tree fungi, you’ve got something to say about it.
Usually, though, that something is more of a question: Why is your nice hardwood tree losing branches? What can you do about it? And what do you need to know about fungus in the United States in general?
Today’s post contains the most important answers to these questions. We’ve gathered information from the most reputable sources as well as our long experience in tree care, and we’re here to share it with you.
What You Need to Know About Fungus Growing on Trees
Many people are concerned about fungi attacks on trees even before they have a problem, and rightly so. Mushrooms and other types of fungi can do more than grow on the outer surface of your trees; they can also develop within them and beneath the surface of the soil.
It’s critical to know what to do about this. First, let’s answer some basic science questions.
What Is Fungus?
Google defines fungus as “any of a group of spore-producing organisms feeding on organic matter, including molds, yeast, mushrooms, and toadstools.” Fungal species grow throughout North America and the world, found everywhere from your average forest ecosystem to waterways, gardens, and inside our homes.
A fungal infection can manifest in many ways. You might see mushrooms growing on a tree trunk, and often when you see wood decay fungi are responsible. They can affect any part of the tree, so you might first notice them in the form of an infected branch, mottled tree bark, or dead wood.
You might also see a fruiting body – what we would call a mushroom, though this is just part of the specimen. It’s responsible for releasing asexual spores that spread fungal disease. It may also spread through fungal spores or mycorrhizal fungi, long filaments that spread through soil.
It’s important to note that plenty of fungi are friendly, performing critical decomposition and nutrient cycling roles in wide-ranging ecosystems. They also fix carbon dioxide in the soil, so can potentially help to reduce climate change.
What About Lichen?
Many homeowners and garden enthusiasts also wonder about lichen. It’s everywhere, so you might be understandably nervous about it.
The good news is, you don’t need to worry. All lichen species, from fruticose lichen to crustose lichen, are self-sustaining. That
means they harvest water and sunlight from the environment around them to live and grow. Like moss, they stay on the surface and do not draw nutrients from trees, so they’re fine to leave wherever they develop.
What Kind of Damage Can Fungus Cause for Trees & Tree Roots?
Now for the types of fungus that grow on trees and can do damage. Yes, plenty of friendly fungi form a symbiotic relationship with their host, but if your trees are dying, that’s an act of war. Like carpenter ants, they’re great in the forest and super not great in your landscape specimens or foundations.
Two of the most dangerous types are root rot and collar rot. Let’s take a look.
Root Rot
Root rot, as the name suggests, affects the roots of trees and other plants, indoors and out. When infected, tree roots become slimy and mushy, incapable of taking up water, oxygen, and nutrients. Root rot is caused by a range of fungi, including:
Armillaria: Also known as shoestring fungus, this genus affects all types of plants, including palms, succulents, and trees. The first sign is dropping leaves, as well as yellowing and upper limb dieback.
Phytophthora: Usually infecting trees and plants in poorly drained areas of the yard, this genus usually manifests as quickly wilting and dying leaves and branches with the onset of heat.
Pythium: While often associated with grass die-off, Pythium species can also infect every type of conifer and hardwood. They may cause plants to lose leaves, branches, and limbs, or simply stop growing.
Fusarium: Often associated with stressed or injured trees, symptoms of this genus include wilting, yellowing leaves, and decayed roots. It can affect all kinds of trees and many other plants.
Rhizoctonia: This type of root rot predominantly affects seedlings and young trees. Symptoms of rot in older trees, however, are likely caused by another type of fungus.
Thielaviopsis: Also known as black root rot, this type of fungus is particularly dangerous for palms. It can eat the plant from the inside out, eventually causing it to collapse completely.
The most pernicious thing about root rot is, because it begins below the soil, it is hard to spot. Eventually, it will manifest in above-ground signs, but even then can be hard to diagnose because of the global nature of the symptoms.
Typically, though, root rot manifests in areas of poor drainage or constant moisture. If you notice signs early and get an expert opinion, you can typically tackle the issue in time to save the tree.
Collar Rot
Collar rot is a fungal infection of the collar, the part of the tree right above the ground that widens beneath the trunk and above the root flare. The collar is technically part of the trunk, not the roots. It needs to stay above ground where it can receive light and nutrients and stay dry.
When it is exposed to too much water or buried in soil, your tree can get collar rot, often caused by Phytophthora species (which, yes, can also cause root rot). A number of other species can cause collar rot, some specific to their hosts, and some more general – like Phytophthora. While collar rot can infect any type of woody tree, it is of particular concern for fruit trees.
Symptoms of collar rot include “Cankers on the trunk between the soil line and crown roots, scattered yellow leaves mid-season, a reddish or purple cast in the foliage in late September, [and] sparse foliage and low vigor.”
The only upside of collar rot is that it often occurs before root rot. If you catch it early when it is still higher up on the tree, you can prevent deadly root rot from taking hold.
Other Types of Tree Fungus
Although root and collar rot are the two most pressing concerns for most growers, there are other types of fungus to watch out for as well. These can impact landscape specimens, fruit trees, or forest trees on your land.
The following fungus can infect an older tree or a younger tree, as well as both evergreen and deciduous tree specimens. These include:
White rot: This disease breaks down the wood on the host tree, causing the infected tree to fall apart. The infected tree is often a deciduous species, infected by wood decay species that live on the forest floor or in brushy backyards.
Black fungus: Also known as black knot, this fungus forms bulbous swellings that attack trees, particularly fruit species such as plum and cherry.
Oak wilt: Though often confused with a canker disease, oak wilt is caused by the Bretziella fagacearum fungus and is particularly dangerous to oak trees. Oaks are especially susceptible to it when you prune in late spring to midsummer, so avoid that wherever possible.
Mushroom conks: Also known as bracket fungi or artist’s bracket, Ganoderma applanatum is a species of perennial shelf fungi. Although these look charming in the woods, they aren’t. They eat the heartwood of a huge variety of trees, leading to death.
Powdery mildew: One of the most widespread fungal infections of all, powdery mildew can infect anything from a redwood to a squash plant. Although it is dangerous to seedlings, older trees aren’t at risk. However, its blotchy, whitish spatters may cause unsightliness.
An Ounce of Fungal Prevention Is Worth a Pound of Fungal Cure!
No matter what kind of fungus you have, it’s important to take care of it quickly. Healthy trees are in danger from infected trees nearby, as well as diseased brush and infected equipment from pruning. If you want to avoid a dead tree, you have to look alive.
Fungus, happily, is not a given on your trees. In addition to planting trees in well-drained soil, keeping them watered during hot spells, and watching carefully for signs of rot, you should reach out to a tree care service to help keep fungus in check today.
How Can Rojas Tree Service Help with Tree Fungus?
Many tree lovers, after reading the above, start to get concerned – but never fear! With a good arborist on your side, you can dispense with the worry and ensure your trees are in good hands all year round.
Rojas Tree Service is North Atlanta’s favorite choice. We focus on tree trimming, removal, stump grinding, and lot clearing. Doing so will help keep trees in your yard, garden, and orchard healthy and fungus-free. If you have a special concern, we’re delighted to help you with that as well.
Ready to book a free consultation on tree fungus or any other service? We invite you to visit our site or give us a call at 678.616.9124 right away. Don’t wait to give your trees the TLC they deserve!
