Mycorrhizal Fungi For Your Plants: What Are Their Uses And Benefits?

mycorrhizal fungi bacteria

What are mycorrhizal fungi, actually?

The adjective ‘mycorrhizal’ is made of two parts: myco-, from the Greek word for fungus, and -rrhiza, from the also Greek word for root. So, fundamentally, a mycorrhizal fungus is a root fungus; a species of fungi that lives and thrives on the roots of plants. When these fungi begin their growth, they do so by associating themselves with the root systems of plants.

At school we are sometimes taught that fungi are decomposers; that their role is basically to exist upon dead things and break them down to their smallest components. This is true for some species of fungi, but not for all of them. Some, like these mycorrhizal ones, exist in what is called a symbiotic relationship with the plants that host them; a relationship in which both parties benefit from their association and none of them is harmed.

This association of mycorrhizal fungi and plants has in fact been going on for millions upon millions of years, possibly all the way since the first terrestrial plants appeared. Some scientists believe that, when algae began to colonize dry land four hundred million years ago, these mycorrhizal fungi first gave them the stability that they needed to become established, and later produce their own root systems over time.


Why do they matter for gardens and farms?

So, they’re historically a big deal, but why do mycorrhizae matter now? That is, what benefits do they actually bring to the present gardener or farmer? The answer to that is related to what we saw above: basically, mycorrhizal fungi benefit plants today in the same manner that they did millions of years ago, by serving as extensions of the plant’s roots in more than one sense.

  • Being smaller than the average root (being microscopic, even), the mycelium of these fungi can get to where plant’s roots can’t. This means access to a whole range of micronutrients that are trapped in very small pockets of soil, underground water, and nutrients in surrounding organic matter.
  • Being natural decomposers, these fungi can also dissolve and make usable a lot of nutrients that are not entirely available to plants in their raw states. Iron, for example, is a mineral that they dissolve by secreting acids in small quantities, in order to allow the plant’s roots to absorb it.
  • By outcompeting other organisms that want to colonize the plant’s roots, sometimes even producing antibiotic substances to eliminate them, these mycorrhizal fungi form a protective barrier around the root systems of their plant hosts, greatly reducing their exposition to disease.
  • These fungi also generate a small number of immune stimuli to the plant, generating an equally small but enduring immune response. Mycorrhizal fungi thus serve as a sort of ‘plant vaccine’ that favors the development of a healthy immune system in the host plants, which allows them to better resist real threats.
  • As if the former advantages weren’t enough, mycorrhizal fungi have also a strong impact in how well plants can adapt to changing climatic conditions; including an increased resistance to drought, heat, cold and salinity, and even metal toxicity. Even chemically contaminated soils are restored with the aid of mycorrhizal fungi.
  • Finally, when their host plant is under the attack of an insect pest, mycorrhizal fungi produce organic substances destined to attract the predator of those insects. They do so by mirroring the same processes that the plant follows to produce those organic substances, serving to double the plague’s predator attraction.


How can we be sure of their usefulness?

All of these beneficial impacts are documented by scientists, even some of them that have only recently been discovered (suggesting that many more are yet to be identified). But there’s no need to take our word for it: here’s a handful of scientific papers discussing what we’ve said above. In addition, you can check here for more information on the positive effects of these fungi on the plant’s immune system; here for a detailed case of how they help plants to absorb nutrients, and here for a really interesting explanation of how plants communicate using subterraneous networks of mycorrhizae, to alert each other of plagues and pests.

In addition, here are a couple of resources for you to delve more deeply into the world of mycorrhizal fungi. Here’s a link to the New York Botanical Garden’s article on the matter, a similar one to the Royal Horticultural Society of the UK, and one more to the Mycorrhizal Associations Web Resource. That last one has a great introduction to mycorrhizal fungi, even detailing the many types of these fungi that exist and what each of them specifically does. In fact, they have a list of some of the main documented benefits of mycorrhizae, which it’s definitely worth checking out.


How can you get them on your plants?

So, mycorrhizal fungi are great. They’re the cream of the crop, they’re the top, they’re the pick of the litter: how do you get them on your plants? Well, if it weren’t so difficult to actually spot them and to actually remove them and inoculate your plants with them, what you could do would be to dig some mycorrhizal fungi that are already present in the edge of a forest or in your own garden and begin to spread it around. The great problem is that not every species of mycorrhizal fungi (because there’s many) will actually colonize every species of plant, mainly because they have evolved over time to specialize and focus on one or just a few. Another problem is that to actually inoculate with already existing fungi you’d have to dig out plant’s roots, possibly killing them in the process, without actually being sure that the inoculation will work out because you’d be basically cutting pieces of fungi and spreading them around, hoping for the best.

So, the best way to ensure that your plants are reaping all the benefits of associations with mycorrhizal fungi is by applying them at the moment of planting, and then renewing applications of spores of these fungi each year. Spores are fungal seeds: they’re also hard to collect on your own. Fortunately, a good deal of products are sold specifically to inoculate your garden or farm with mycorrhizal fungi: why don’t you take a look at ours here?

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