Mycorrhizal Fungi: The Hidden Allies Beneath Your Plants’ Roots

Unlocking the Underground Network: What Are Mycorrhizal Fungi?

I’m Dr. Russell Sharp, and in this blog we’re talking about something microscopic but mighty—mycorrhizal fungi.

The term mycorrhiza combines myco (fungus) and rhiza (root), describing the mutualistic partnership between fungi and plant roots. This ancient alliance dates back millions of years and plays a crucial role in plant health, nutrient uptake, and ecosystem stability.

Why Do Plants “Feed” Fungi?

Plants share up to 15% of their photosynthetically produced sugars with mycorrhizal fungi—about the same energy they would use for flowering or fruiting. That’s a massive biological investment. So, what do plants get in return?

• Enhanced phosphorus absorption (especially in soil)
• Increased stress tolerance (drought, flooding, salinity)
• Better resistance to root pathogens and diseases
• Improved soil structure and microbial diversity

Are Mycorrhizae Useful in Hydroponics?

In hydroponic systems, where phosphorus is abundant, the nutrient uptake role of mycorrhizae is less pronounced. However, they can still help with:

• Root health
• Disease suppression (e.g., root rot)
• Stress tolerance under suboptimal conditions

Not All Plants Use Mycorrhizae

Surprisingly, about 10% of plant species don’t form mycorrhizal connections, including:

• Brassicas (cabbage, broccoli, mustard)
• Proteas (many South African species)

Some plants already exude chemicals to extract phosphorus efficiently, making mycorrhizae unnecessary. Others may avoid them as a defence against fungal pathogens masquerading as beneficial fungi.

Fascinating Examples: Orchids and Pines

• Orchids require mycorrhizal fungi to germinate. Their dust-like seeds can’t grow without fungal support.
• Conifers (like pines) thrive with mycorrhizal associations and are often inoculated intentionally in nurseries to boost survival and nutrient uptake.

How to Know If It’s Working? You Don’t.

One challenge with mycorrhizal products is that you can’t visually confirm if inoculation was successful. Unlike diseases that leave visible symptoms, mycorrhizae operate behind the scenes. You might never know if they:

• Prevented a root disease
• Improved water uptake
• Outcompeted pathogens

This leads some growers to think of them as “optional extras”—especially when they come at a cost.

Risks and Real-World Results

💡 Tip for Grow Shops:
Rotate your mycorrhizal stock frequently. These are living organisms, and like all lifeforms, they die over time—especially if stored improperly.

🔍 Mixed Results in Trials:

• Positive: Strong outcomes in bamboo and certain trees
• Negative: Growth inhibition in some grasses due to bulk fillers in commercial products

Types of Mycorrhizal Fungi

There are three main types of mycorrhizae, each with distinct roles:

1. Endomycorrhizae (Arbuscular)
   • Penetrate root cells
   • Common in herbaceous plants and orchids
   • Excellent for nutrient absorption in poor soils
2. Ectomycorrhizae
   • Form a sheath around roots
   • Found in trees like oaks, birches, and pines
   • Aid in toxin resistance and heavy metal tolerance
3. Vesicular-Arbuscular Mycorrhizae (VAM)
   • Live between and inside root cells
   • Enhance root surface area significantly (e.g., 80 cm of fungal strand per 1 cm of onion root!)

Weird and Wonderful Fungi

• Truffles: Yes, they’re a form of mycorrhizal fungi!
• Fly Agaric: The red-and-white mushroom famed in fairy tales (and Norse folklore) is also a mycorrhizal species.

Final Thoughts: Should You Use Mycorrhizae?

If you’re growing crops in soil, media, or even hydroponics, exploring high-quality mycorrhizal products could be beneficial—especially for long-term or stress-sensitive plants.

However, avoid high-phosphorus fertilizers and biocides like hydrogen peroxide, which can kill beneficial fungi. And always check product freshness—because dead fungi don’t help anyone.

Let us know in the comments: Have you tried using mycorrhizae? What were your results?

Article by Dr Russell Sharp

If you would like to keep up to date with subjects just like this, you can listen to both our podcasts! Links can be found bellow:

Hydroponics Daily Podcast: https://open.spotify.com/show/207T7p7fw9sPjINfSjVXW2

Cereal Killers Podcast: https://t.co/eSEbBkTVHl