Helpful Tree Fungus

Most trees depend on mycorrhizae.

Most trees depend on mycorrhizae.

The word fungus does not often conjure up good thoughts. However, for trees, some types of fungi are good. Some species of fungi help bring needed moisture and nutrients to tree roots, which can be especially helpful during droughts. Mycorrhizae, a fungus found in the soil, has a symbiotic relationship with trees. The fungus helps the tree take up water and nutrients in exchange for sugars.

Types of Mycorrhizae

There are two main types of mycorrhizal fungi: ectomycorrhizae and endomycorrhizae. Ectomycorrhizal symbiosis happens when the fungus coats the roots of the tree and spreads into the soil around the tree. This brings the nutrients to the tree while the tree gives the fungus the carbohydrates it needs to survive. Endomycorrhizal symbiosis is the more common type of partnership between tree and fungus. Instead of covering the roots of the tree, the fungus only has a few attachments to the tree roots. Through this attachment the fungus creates a bridge to the surrounding soil for the tree.

Symbiotic Relationship

Tree roots push outward and downward in search of nutrients and water as the tree grows. The furthest tips of the roots may be no larger than the width of a hair. This is where the mycorrhizae fungus attaches itself. The fungus creates a line from the tree root to the surrounding soil, enabling the tree to receive more nutrients than it otherwise would have. In return, the fungus receives carbohydrates from the tree. Since this relationship does not harm either the tree or the fungus, it is considered a symbiotic relationship.

Importance of Mycorrhizae

Because the mycorrhizae fungus essentially extends the trees' roots further than they would have been able to do on their own, it helps the tree survive during times of stress. For example, if the area is suffering a drought, the fungus helps bring more water to the tree. The water helps keep the tree healthy so it can better fend off diseases or pests. Mycorrhizae can also be added to soil that has suffered damage and is nutrient poor, such as from hazardous waste or mining. Trees planted in an effort to reclaim the natural environment will have the help they need to be healthy.

Urban Uses

Landscapers and garden supply professionals recommend using mycorrhizae when planting or transplanting trees, especially in urban areas. Soil may be damaged by the pollution in urban areas and the fungus helps the trees thrive and grow well. The mycorrhizae is injected into the ground around the tree where they are left to establish themselves. It is best to consult with an arborist to determine the right strain of fungus to add to soil in your yard.

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