What are Mycorrhizae?

Posted at March 3, 2011 | By : | Categories : Articles | Comments Off on What are Mycorrhizae?

The word mycorrhizae (pronounced My-cor-rye-zay) refers to a group of fungi which form a mutually beneficial relationship with many plants. These fungi grow either inside of a plant’s roots or attach to the surface of a root. The fungi benefits from the plant’s food and nutrients and in turn send their hyphae (like small roots) out into the surrounding soil to absorb nutrients and water.

So, mycorrhizae actually enhance a plant’s ability to take up nutrients and water. Because of this, research has shown that the presence of mycorrhizae also help plants deal with drought and some diseases. Approximately 95% of the world’s plants have some form of mycorrhizal dependence. As far as growing is concerned, in many cases, increased root and top growth occurs when plants are treated with mycorrhizae. These benefits are not always evident, especially on short term crops, unless the crop is stressed or planted into a landscape where water and nutrients are less available.


There are two main groups of mycorrhizae – Ectomycorrhizae and Endomycorrhizae. Both groups are specific in what plant types they will work with. Ectomycorrhizae forms relationships with birch, oak, spruce, pine and fir, but is not important to most greenhouse growers since the above plant types are not typical greenhouse crops.

The second group of mycorrhizae is endomycorrhizae which are also known as vesicular-arbuscular mycorrhizae or VAM. Roughly, 80% of all the plants in the world form associations with endomycorrhizae, as does nearly every greenhouse plant. So, this is the group of mycorrhizae that is most important to greenhouse growers, and the everyday grower. It is the one that you want.


It is not difficult to create a good environment for endomycorrhizal (VAM) colonies, all that’s needed is a plant that forms a relationship with VAM. After that, the primary factor is the amount of inorganic phosphorus in your growing system. Since the relationship between plant and fungi evolved to help the plants access low levels of phosphorus in the soil, mycorrhizae do not grow and colonize roots when the phosphorus level is high. Phosphorus levels above 10 ppm in the soil solution will negatively impact the growth and establishment of mycorrhizae. A high phosphorus level does not kill the mycorrhizae, it just creates an environment in which the mycorrhizae do not germinate and grow, and this renders them ineffective. As a grower, you should use low phosphorus feeds for the first 30 days to allow the mycorrhizae to grow.

Typical lime rates and medium pH levels of Grower’s Gold growing medium products do not have a significant positive or negative effect on the growth and colonization of mycorrhizae.Chemical fungicides should be avoided especially at the start of production and until enough time has elapsed to allow root colonization to occur.

The Sun Gro technical team has found excellent colonization results when mycorrhizae is added to Grower’s Gold growing mixes. Organic fertilizers release their nutrients slowly over time so the levels of phosphorus remain within a tolerable range for good mycorrhizal growth and colonization. Since we wish to supply our customers with the best performance, we are offering Grower’s Gold growing mixes with mycorrhizae.

Other media products in the market offer single species of endomycorrhizae or offer a blend of endo and ecto mycorrhizae. Grower’s Gold growing mix amended with mycorrhizae use a blend of endo species designed to enhance colonization under a wide range of growing conditions. We do not add ectomycorrhizae since they provide no benefit to most crops.



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