At Texas Tree Surgeons, we love trees and we love our customers, and we have created a series of articles covering tree basics. If you have a specific tree question, let us know!

Mulch is an important part of tree care that is often overlooked. Many trees are surrounded by turf grass or other plants, which can stifle their growth. Proper mulching can be the key to trees that not just survive, but thrive.

In nature, trees live in a complex organic environment. A forest can be made up of hundreds of different plant and animal species, each contributing something to its surroundings. The forest floor is composed of layers of organic material, from fallen and rotting trees to tiny plants that serve as ground cover. This complexity provides a habitat for animals, plants, and microorganisms. In this environment, a tree is able to send out its roots into rich, fertile soil and get the exact nutrients it needs to thrive.

In our urban environment, trees are often in competition for resources with turf grass.  or may even be surrounded by non-organic materials, such as concrete. The soil around a tree can easily become compacted due to above-ground traffic. While we cannot completely re-create the forest environment in a city, we can help reduce soil compaction and competition by correctly mulching around trees. When mulch is properly applied and maintained, trees are able to grow sturdier root structures, tree health is improved, and we benefit from hardier trees that can live for decades.

Does the Type of Mulch Matter?

Despite the various ways that mulch is marketed, packaged, and sold, there are only two basic types: organic and inorganic. Organic mulch is made up of plant material, and can come from a variety of sources. Wood chips, bark, nut shells, and pine needles are common components. Inorganic mulch includes anything that is not plant or animal material and does not break down naturally. Crushed stone, recycled tires, and landscape fabric are common types. While inorganic materials can be useful in certain landscaping applications, they are not beneficial to trees, and may actually be harmful if used as tree mulch.

Choosing the best mulch requires understanding the needs of your tree and the underlying soil conditions. Soil density, pH, drainage, and composition all have an effect on the ability of a tree to send out roots and get the nutrients it requires. While mulch is not primarily a fertilizer, it is composed of organic matter. Insects, earthworms, and microorganisms break down the organic material become food for the tree. Mulch selection and maintenance can influence which types of organisms are able to survive in the mulched area and benefit (or harm) the tree.

Most commercially-available mulch is made from tree material that is shredded to a consistent size, partially composted, and often dyed brown, black, or red. Commercial mulch is generally long-lasting and a good basic mulch. We recommend sourcing mulch from a reliable local producer that does not use chemical treatments or dyes, but composts mulch naturally.

In addition to general-purpose mulch, many producers offer mulch produced from a particular material, which can be used to alter or amend the chemical composition of the soil. Pine bark, for example, is acidic, and cedar mulch contains cedar oil, which can be a natural insect repellent. Other materials, such as nut shells or pine needles, may be available and can be helpful when mulching a particular species. Contact your arborist to see about mulch producers in your area/

Can I Use Wood Chips or Grass Clippings as Mulch?

Tree care businesses or municipalities may sell wood chips produced as a waste product of tree trimming or removal. If you have tree work performed, the tree trimmers may leave wood chips behind. These chips can be a cost-effective way to get organic material, but are not identical to commercially-produced mulch. Best practice is to compost any fresh wood chips before using.

Grass clippings, leaves, and other landscape waste material should be thoroughly composted before use to help prevent weed growth and neutralize any chemical imbalances. Sawdust should likewise be composted first, but sawdust from treated lumber should never be used as mulch. If modifications to soil pH are recommended, certain materials can be added uncomposted to mulch to achieve the desired effect. Ask your arborist for any special needs your trees may have.

The Right Mulch for You

In North Texas, it is common to have fairly dense, clay-like soil that tends to be more alkaline than acidic. Ensuring good drainage during wet weather can be difficult. In dryer periods, the soil can harden and crack. Mulch can help create a stable, permeable layer that can regulate moisture better than the underlying soil. Mulch also insulates the shallow roots from swings in temperature that we can have during the spring and fall. Most native trees and shrubs are adapted to the natural soil pH and composition, and only need basic mulching. Other species, however, may benefit from slightly acidic mulch.

At Texas Tree Surgeons, we love trees and we love our customers, and we believe that the more people learn about their trees, the better we can serve our community. We hope this article has helped answer your questions about mulch. If you have any specific questions, let us know, and we’ll be happy to send an arborist out to evaluate your needs and offer our suggestions and expertise.

-K.N.

As we’ve mentioned before, all this rain has really been a mixed blessing. While we are happy to be safely out of drought conditions, many issues that we don’t see in drier weather have started presenting themselves. Fungi, which thrive in moist environments, have been growing rapidly, sometimes seeming to appear overnight. While a few toadstools in your yard may not indicate a serious problem, visible fungal growth on trees is something to be on the lookout for and may need to be addressed.

There are a wide variety of different fungal species that can live in the soil around trees. Some are beneficial, and are part of a healthy soil ecosystem. Others, however, can spread through a tree’s living tissue and cause health problems for the tree. We have seen problems with Chinese pistaches recently that are caused by a proliferation of fungi due to the wet weather. In the past few years, Italian cypresses have also been afflicted with health issues due to the spreading of a particular fungus. In both these cases, there were little or no warning signs or visible “mushroom” growth before the trees started browning and dying back. However, there are some fungal infections that exhibit visible growths and can be diagnosed before the tree is too far gone.

Ganoderma

Ganoderma is the name of a genus of fungi, and there are several different species that are present in the environment. While the different species vary in appearance, the ones commonly seen in North Texas generally mature into ear-shaped growths called “conks.” The conks may appear on a tree trunk, near the base, or even grow right out of the ground. The conks begin as white- or light-colored, but darken into dark orange or brown with a shiny appearance on top. Oaks and elms are particularly susceptible to Ganoderma, but other species can become infected, as well.

Ganoderma, like Kretzschmaria, is present in the soil, and infects a tree when its roots become damaged and lose their protective bark. While Ganoderma is similarly untreatable, it can be easier to detect in its early stages and may be able to be managed, avoiding immediate removal. Root zone excavation can also be helpful in determining the extent of damage.

ARE ALL MUSHROOMS BAD?

While Kretzschmaria and Ganoderma can cause serious tree stability and health problems, not all visible fungi are a hazard. Fungi in the genus Laetiporus (such as sulfur shelf or chicken of the woods mushrooms) can live on a tree trunk for years without harming the tree. Common white toadstools, such as those in the genus Lepiota, may appear in lawns as a result of beneficial fungal growth in the soil. In periods of heavy rain, species that are usually hidden underground may show visible growths. If you see mushrooms or other fungal growth in your yard or on your tree, send us a photo, and we are happy to let you know if it’s something to be worried about. We love trees and we love our customers, and we always want to help you understand the complex ecology of our urban forest.

Have a specific tree question? Let us know, and you may see it answered in a future Ask Texas Tree Surgeons installment!