Yes, You Can Grow, Cultivate, and Harvest Your Own Mycorrhizal Fungi!

Most of us have heard of mycorrhizal fungus and are well are aware of it’s vital importance to most crops grown worldwide.

Knowing how essential these Mycorrhizal fungi are to plants health and vigor, we certainly want to make sure that they are present in our root zones at every planting and transplanting that we do.

If we do a great deal of this, we may need to go through quite a lot of mycorrhizal fungus spores and propagules to get all of the plants sufficiently inoculated. If you have to purchase very much of these products, you will find that the costs can add up surprisingly quickly. For many of us, this can cause us to use less than we should, and our plants will suffer from the loss.

But many people were not aware that they could make their own, or rather cultivate their own, through relatively short and simple processes. The procedures can vary, but they have many similarities in their processes.

The ectomycorrhizal fungus is certainly the simplest type to propagate due to the fact that it is the type of fungus that makes visible fruiting bodies, known as mushrooms, which are easily collected.

These mushrooms, bits and pieces, are always covered in viable spores that have great potential to germinate when they are spread around in the environment. Particularly, if you add cut up bits of mushrooms to each planting hole you plant into.

In fact, you can drop all the mushrooms that you can find in the forests (except for the Honey Mushroom, AKA Armillaria mellea ) into a blender, and pour that puree into a sprayer full of water and spray it out over all of your trees and shrubs. There is no overdose potential and no special procedure except that it be blended fine enough to pass through the sprayer apparatus. The results are often amazing improvements in the health of the plants who received the sprays.

Endomycorrhizal fungi can reproduce easily, from the spores and vesicles they grow inside inoculated plants roots. They survive in dead plant roots and can germinate again when in contact with new living plant roots.

To collect indigenous endomycorrhizal fungus, you require a good set of soil sieves and time to take collections of soil from the locations where you know that indigenous mycorrhizal fungus was present. Of course, if you were incorrect, you would know after the sifting and checking the microscope images.

The sieves required are 750 micrometer mesh to do the initial sieving, followed by a 250 micrometer mesh for the second sieving, then a third pass through a 100 micrometer mesh sieve and FINALLY a pass through a 50 micrometer sieve, so that nothing but mycorrhizal spores remain in the sieve. You will need a microscope or powerful hand-lens to see them, but they should be there.
Another way to easily collect and use indigenous mycorrhizal fungi is simply to collect the roots, with the dry soil attached, and shake that soil into a container to run through the sieves, but also take that root mass and chop it into little pieces between approximately 1/4”-1/2” in length.

These dried root bits can be stored for up to a year in a cool, dry place. They can be used at any time during that period to inoculate any other suitable plant type by merely including them in the immediate root zone of every plant you put into your garden or your pots. They contain countless viable propagules and spores.

Now, also knowing that certain types of plants prefer specific strains of endomycorrhizal fungus, you can create your own cultures of those specific strains by first purchasing or obtaining them from a reputable source of high-quality mycorrhizal fungus. Then after inoculating your plants with those specific strains, you can collect them, by the methods just described previously. That way you know that if Rhizophagus intraradices, for instance, is the only strain that you really want, you can get as much of it as you want, by cultivating it in this method.

You can do this through more sterile procedures for more reliable results, and it’s not a great deal more difficult.

For instance, by following the “Greenhouse Method”, you can achieve a great deal of success.

You would start with assembling the required equipment to begin the process:
* Plastic pots (6”-10” diameter is ideal)
* Host plant seeds
* Paper towels
* Plastic bags
* Sterile growing medium
* Commercial mycorrhizal inoculum
* LOW-phosphorus, LOW-nitrogen fertilizer

First you must sterilize the plastic pots to remove any living bacteria which would compete with the mycorrhizal fungus and possibly prevent successful germination.

Next, thoroughly rinse off any disinfectant from the sterilized pots.

After that, Soak the host seeds for only 5 minutes, in a solution of 1 part bleach to 9 parts water. It’s important that the bleach is a 5% concentration listed on the bottle!

Then rinse those seeds thoroughly in sterile water (any water that has been boiled and allowed to cool)

The next step is to take the soaked, rinsed seeds and to place them between two paper towels, which will be then placed into some sort of ziplock type bag to maintain sterility through the germination process.

Once the seeds have germinated, plant them into the pots in their sterile growing medium. One part peat moss to 3 parts vermiculite is a good sterile medium. Rock wool is also acceptable (pre-soaked, of course) or coarse-grade, clean sand or regular sterilized soil.

If you want to sterilize regular soils, heat it in the oven for an hour at approximately 350F, or use a pressure cooker for an hour until temperatures of 140F-158F (60C-70C) are achieved.

It’s very important that the medium be free of phosphorus and nitrogen in order to facilitate the germination of the fungus.

When your host plants are growing, you will need to feed them periodically, of course, but be sure that your total phosphorus percentage of the fertilizer that you are using doesn’t exceed 6 percent total from all sources. Some good food sources include Fish Emulsion, Soybean Meal or Alfalfa Meal, which all contain appropriate, safe amounts of phosphorus. Compost and compost teas are good plant food which will ensure that you don’t have excess phosphorus available.

You should expect to have colonization by this method within approximately 6 weeks.

After approximately 14 weeks, stop watering and allow the growing medium to get completely dry.

Around the 16-week point, it’s time to shake the dried dirt off the dead rootstock sift through the sets of soil sieves mentioned earlier. Save all the spores from the 50 micrometer sieve and store in a cool and dried place for up to a year.

After this, the final step is to chop up the roots themselves into tiny pieces (1/4’-1/2” ideally). These pieces should also be stored in a cool and dry place until you are ready to use them as you would any commercially prepared inoculum. It is good for up to a year, in storage, as long as it’s kept in appropriate conditions.