WHAT ARE MYCORRHIZAE?
Mycorrhizae (pronounced My-cor-rye-zay) are fungi that form mutually beneficial relationships with the roots of certain plants. These fungi have mycelium that either grow either inside of a plant’s roots (Endomycorrhizae) or attach to root surfaces (Ectomycorrhizae). Both the fungi and plants benefit. The fungi benefits from the plant’s food and nutrients, and the fungi send out their hyphae (like small roots) out into the surrounding soil to absorb additional nutrients and water, which benefits the plants.
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 helps plants better withstand 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.
TYPES OF MYCORRHIZAE
There are two main types of mycorrhizae – Ectomycorrhizae and Endomycorrhizae. Both types develop certain plant-fungi associations. Ectomycorrhizae species form relationships with birch, oak, spruce, pine and fir trees but are not important to most greenhouse growers.
Endomycorrhizae, which are also known as vesicular-arbuscular mycorrhizae or VAM, are far more common and develop relationships with many economically important herbaceous plants. Around 80% of all the plants in the world form associations with different species of endomycorrhizae. This includes nearly every greenhouse plant. These are the mycorrhizae that are important to greenhouse growers.
WHAT INFLUENCES MYCORRHIZAL GROWTH?
It is not difficult to create a good environment for endomycorrhizal (VAM) colonies. Simply plant the right host plant with the right endomycorrhizae and you are set. The proprietary mix of endomycorrhizae selected for Sunshine Advanced mixes will colonize many species of greenhouse plants, so growers can be confident in choosing our myco-enhanced mixes! From there, several growing conditions need to be considered.
The primary environmental factor of concern is the amount of inorganic phosphorus in your growing system. The relationship between mycorrhizae and their host plants evolved to help the plants access low levels of available phosphorus in the soil, so mycorrhizae do not grow and colonize roots at high phosphorus levels. Phosphorus levels above 10 ppm in the soil solution will negatively impact the growth and establishment of mycorrhizae. High phosphorus levels do not kill the mycorrhizae but create an environment where they will not grow, and this renders them ineffective. As a grower, you should use low phosphorus feeds for the first 30 days to allow mycorrhizae to grow.
Chemical fungicides should be avoided, but if their are needed, wait to use them until enough time has elapsed to allow root colonization to occur. Four to six weeks should provide ample time.
GROWER’S GROWING MIXES
The Sun Gro technical team has found excellent colonization results when mycorrhizae are added to Sunshine Advanced grow 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 offer two top-quality grow mixes with mycorrhizae, Sunshine® Advanced Mix #4 Growing Mix, Sunshine® Mix #4 Aggregate Plus with Mycorrhizae, Sunshine Advanced Rain Forest Blend, and Sunshine Advanced Ultra Coir.
COMPETITIVE GROWING MIX PRODUCTS
Other media products in the market offer single species of endomycorrhizae or a blend of endo and ecto mycorrhizae. Sunshine Advanced mixes 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 greenhouse crops.