Fungi and Plants and their relevance for gardeners

 In Gardening

Fungi and plants have a very close and not always negative association.

The reaction from gardeners to finding fungi and plants together in their garden is often one of alarm! However in many cases there are absolutely no reasons for concern.

This close association of some fungi and plants as we shall see is something to positively encourage. Read on!

Walking my dog in our nearby wood I’m struck by the musty smell of autumn.

Toadstools, fallen leaves, dog, woodland

A large toadstool ring in fallen leaves

It’s not unpleasant and in fact I quite like it. It’s a sure sign that fungi are at work!

The carpet of fallen leaves is already under attack and being broken down by fungi. Obviously in this case it’s a good thing!

All the nutrients accumulated in those leaves are being recycled. As a result they will be available to the trees to grow more leaves again. I’m sure that you will agree that this is a very positive association of fungi and plants!

But in the minds of many gardeners most fungi are thought to be a threat. Of course many indeed are and cause diseases. Nevertheless far more are beneficial and indeed vital to get good plant growth.



Symbiotic Fungi and Plant Relationships

Most plants have a symbiotic relationship with fungi. This goes unseen since it involves the roots of plants and is hidden underground.

I was reminded of this recently when inspecting pot grown Strawberry Trees [Arbutus unedo].

These plants were small when we potted them up. And yet they were now ten times the size, strong, healthy and full of flower only a few months later!

We used to struggle growing Arbutus well and many didn’t make it to a saleable size. And feeling that the plants lacked something that we couldn’t really put our finger on we tried adding root friendly fungi to the pots.

mycorrhizal fungi on Arbutus roots

Bracket and toadstool fruiting bodies on strong pot grown Arbutus unedo [Strawberry Trees]

Well what a difference that made! I felt that this graphically illustrated the important symbiosis that exists between plants and fungi!






Root Grow

What we added was a product called Root Grow. I recommend that you add it when planting too!

This product is invaluable when planting roses, especially if you must plant where roses have grown before.

But it works for fruit trees too.

And it doesn’t stop there because almost every plant grows better when it has this almost invisible sheath of fungi [actually called mycorrhizae] covering its roots.

The friendly fungi sheath increases nutrient and water absorption by the plant and takes a little of what the plant has to offer in return.

mycorrhizal fungi on pine roots

Massive mycorrhizal growth on roots of a pine tree

If you get the opportunity to see pine tree roots then the friendly fungi sheath shows itself as a white covering. This is sometimes mistakenly thought to be harmful.

Of course that could be no further from the truth!

We added Root Grow when potting pines and monkey puzzle trees when we had our nursery.

We found that the powdered product works best when in direct contact with the roots.

I think you can see from this image that we have achieved a very strong symbiotic relationship between fungi and plants on our pot grown Mountain Pines!

All the white fungal mycelium has completely covered the root system of our pines.

I’d strongly recommend that you too add Root Grow to the planting hole when you’re planting. You’ll get better establishment and growth than planting without it.

If you want to know more about Root Grow and friendly mycorrhizal fungi read this.



Some of the Harmful Fungi

Honey fungus toadstools, fungi

Masses of honey fungus toadstools on a dead tree

I know what you are thinking and yes there are harmful fungi that attack roots of many plants.

But often these are old and weakened plants or plants that have become stressed or damaged.

Top of that list is ‘Honey Fungus’ [Armillaria mellea].

Few woody plants show any resistance to what is also sometimes called ‘Bootlace Fungus’.

But all soft stemmed plants remain largely unaffected by the presence of this pathogen in our soils.

Often this disease attacks a weakened tree then kills it. The organism feeds on the trunk and roots until all the food in it is consumed.

Honey fungus then has the ability to send out the equivalent of its root system to find and attack another tree nearby.

Honey coloured toadstools are where it got one name and the thick bootlace like rhizomorphs that grow under the bark is where it got the other. The toadstools are variable and so diagnosis from them alone can be tricky.

Little can be done to control honey fungus except to promptly remove an afflicted tree and its roots. Also do try your best to avoid surrounding woody plants becoming stressed.

There is a list of trees that show some tolerance to honey fungus but I’m afraid that they are not the most ornamental trees available!

It’s on this link here and you will need to scroll down to the ‘Download’ subtitle on this page to access it.


But back to where I started with rotting leaves and the role which fungi plays there! Composting garden prunings and waste relies completely on this invisible army!

Sure you can speed things up by adding Garotta or another compost accelerator but the bulk of the work is done by beneficial fungi.

So next time you see a toadstool in your garden, hesitate before you sweep it away because it might be one of those almost invisible beneficial fungi that we couldn’t garden without!

You may want to read more about Honey Fungus here.

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