MYCORRHIZAE - The Latest Horticultural Breakthrough

The word comes from two words: mycorr, meaning fungus; and rhizae, meaning root. Mycorrhizae is a root fungus, actually many different kinds of fungus. It exists in a symbiotic relationship with the roots of plants. It's estimated that 99% of the plants of the world have this mycorrhizal association. It may have been around for millions of years but it is something relatively new and extremely exciting to the world of horticulture. It is due to this symbiotic relationship that the plants of the forest grow and prosper. Due to this beneficial association, the roots are able to absorb a much greater proportion of minerals and water than they are able to on their own. The fungus, in turn, gets 35-40% of the photosynthates that are its food, created by the plant's normal process of photosynthesis. We learned years ago that to plant pawpaw seeds and achieve success, we needed to mix some of the soil from underneath a bearing pawpaw tree with our potting soil before we planted pawpaw seeds.

Also, some years back, Charles Novak received a load of seeds from many of the plants of Brunei, sent to us by Bobby Tee. Several members planted the seeds in our best potting soil and nurtured them as they came up and began to grow. We had several species of durian, two kinds of tarap, mangosteen and others. They grew well up to 6 or 8" and then began to die as the nourishment in the seeds was consumed. Virtually all of the plants died. We can only assume that they were lacking the mycorrhizal fungi they needed.

Fortunately, the elusive mycorrhizae is now being produced on a commercial basis. All of our tropical fruit trees are endomycorrhizal. This is the mycorrhizae that actually live inside the roots. In the tropical jungles, the mycorrhizae digest the litter which continually falls from the trees, being decomposed and recycled back into the trees. It works in conjunction with the roots of the trees and does an absolutely fantastic job.

Now that we can inoculate the soil of a growing plant, mix mycorrhizae with some soil in a ratio of 1 to 10, push a shovel into the ground and push it forward and put a scoopful into the hole. Make several holes in the ground around the tree between the trunk and the drip line. For a small potted plant, poke holes in the soil with a pencil and put a teaspoon of mycorrhizae in each hole. When planting seeds, mix it with the potting soil before planting the seeds.

We don't know whether mycorrhizae will be the panacea that will solve all our problems, but it looks like it's going to be a great help. We have to do a lot of experimentation on this, one of the newest materials in horticulture now commercially available.

After inoculation, the fungi grow in the soil, and unlike fertilizer, it never has to be added to, just nurtured with good soil care. Likewise, we do not know how much or how little to use. We do know it is a very small amount. One thing we do know is that results are not immediate, as with the addition of fertilizer; the fungus must germinate and grow.

I am presently mixing it with the sphagnum moss I use for air layering. I should get a much better root production in the moss in the 6 weeks I normally allow for roots to form. I am mixing 1 teaspoon of mycorrhizae with the sphagnum moss per air layer.

Bob Heath, Tampa Bay, South Florida

DATE: December 2001

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