Mycorrhizae (my-cor-rhi-za) is a unique type of fungi that does not produce its own food source, and therefore relies on the roots of plants for energy. In exchange, the Mycorrhizae make water and nutrients available to the plant that they would otherwise be unable to access on their own. The relationship between the roots and these fungi is symbiotic, which means it is mutually beneficial for both parties.


There are several hundred species of mycorrhizal fungi and they have all evolved perfectly to increase the absorptive capacity of a tree’s root system. The small size, the branching structure, and ability to grow quickly to respond to the specific needs of individual trees make these tiny fungi incredible at finding water and transporting it to the root zone. They also use acid-like enzymes to release essential nutrients, such as nitrogen, phosphorus, and Iron that are bound in the soil. This function is especially important in Toronto because our soils have high clay content and a high pH, making nutrients even more inaccessible than in other cities.

The recent drought has only exacerbated these existing problems. Traditional synthetic fertilizers may flood the required nutrients into the soil, but without a complex network of fungi and bacteria the tree will not be able to access or store them. Unused nutrients often leach out and contaminate nearby water sources.

Having mycorrhizae available in the soil is extremely beneficial to mature trees in an urban environment where soil disturbance has destroyed the delicate structure these organisms need to survive.

At Cohen and Master, we’ve created a custom product for Toronto soils that combines all the ingredients required to give the tree an immediate boost. However, we also recognize that living organisms are required to rebuild a soil environment where the tree can create and maintain a healthy root system on its own. By adding Mycorrhizae and bacteria, along with food sources and nutrients into the soil around your tree, you are providing these valuable landscape features with the resources needed to not only thrive tomorrow but to sustain themselves for decades.

By: Rachael Kowaleski, BES
Consulting Arborist, Cohen & Master Tree and Shrub Services