Human arrogance has always assumed we are evolutionarily superior to plants, but it appears that modern science may be the antidote to this egocentric view.
Researchers in the UK have discovered an extensive underground network connecting plants by their roots, serving as a complex interplant communication system… a “plant Internet,” if you will.
One organism is responsible for this amazing biochemical highway: a type of fungus called mycorrhizae. Researchers from the University of Aberdeen devised a clever experiment to isolate the effects of these extensive underground networks. They grew sets of broad bean plants, allowing some to develop mycorrhizal nets, but preventing them in others.
They also eliminated the plants’ normal through-the-air communication by covering the plants with bags. Then they infested some of the plants with aphids. The results were remarkable.
Most people have no idea how important mycorrhizal fungi are for plant growth. They really are one of the keys to successful growth of plants. In my own garden, I just purchased a 15 gallon vortex compost brewer in which I grow these fungi in large quantities for my ornamental and edible landscape.
Underground Communications Network Thwarts Infestation
The aphid-infested plants were able to signal the other plants, connected through mycorrhizae, of an imminent attack—giving them a “heads up” and affording them time to mount their own chemical defenses in order to prevent infestation.
In this case, the alerted bean plants deployed aphid-repelling chemicals and other chemicals that attract wasps, which are aphids’ natural predators. The bean plants that were not connected received no such warning and became easy prey for the pesky insects.
This study is not the first to discover plant communication along mycorrhizal networks. A 2012 article in the Journal of Chemical Ecology describes mycorrhizae-induced resistance as part of plants’ systemic “immune response,” protecting them from pathogens, herbivores, and parasitic plants.2
And in 2010, Song et al published a report about the interplant communication of tomato plants, in which they wrote:3
“CMNs [common mycorrhizal networks] may function as a plant-plant underground communication conduit whereby disease resistance and induced defense signals can be transferred between the healthy and pathogen-infected neighboring plants, suggesting that plants can ‘eavesdrop’ on defense signals from the pathogen-challenged neighbors through CMNs to activate defenses before being attacked themselves.”
Miles of Mycorrhizae in One Thimbleful of Soil
The name mycorrhiza literally means fungus-root.4 These fungi form a symbiotic relationship with the plant, colonizing the roots and sending extremely fine filaments far out into the soil that act as root extensions. Not only do these networks sound the alarm about invaders, but the filaments are more effective in nutrient and water absorption than the plant roots themselves—mycorrhizae increase the nutrient absorption of the plant 100 to 1,000 times.5
In one thimbleful of healthy soil, you can find several MILES of fungal filaments, all releasing powerful enzymes that help dissolve tightly bound soil nutrients, such as organic nitrogen, phosphorus, and iron. The networks can be enormous—one was found weaving its way through an entire Canadian forest, with each tree connected to dozens of others over distances of 30 meters.
These fungi have been fundamental to plant growth for 460 million years. Even more interesting, mycorrhizae can even connect plants of different species, perhaps allowing interspecies communication.6
More than 90 percent of plant species have these naturally-occurring symbiotic relationships with mycorrhizae, but in order for these CMNs to exist, the soil must be undisturbed. Erosion, tillage, cultivation, compaction, and other human activities destroy these beneficial fungi, and they are slow to colonize once disrupted. Therefore, intensively farmed plants don’t develop mycorrhizae and are typically less healthy, as a result.
Making Farming More Eco-friendly
The discovery that fungi may be providing plants with an early warning system has profound implications for how we grow our food. We may be able to arrange for “sacrificial plants” specifically designed for pest infestation so that the network can warn, and thereby arm, the rest of the crop.7 In order to feed the world’s increasing population, farmers must return to working WITH nature, instead of against it.
Raising food is really about building soil, and modern agricultural practices are degrading million year-old topsoils, without any attention to rebuilding them. Spreading toxic chemicals, monoculture, using genetically engineered seed, generating toxic runoff and destroying biodiversity are all examples of working against nature. Mycorrhizae not only assist the plants in staying vital and healthy, but they enrich the soil and improve its productivity, add organic matter, protect crops from drought, and increase the overall balance and resilience of the ecosystem.
Mycorrhizae’s Excellent Cousin: The Mushroom
Many fungi are as beneficial to people as they are to plants. Mushrooms are powerhouses when it comes to nutrition, with high-quality protein, enzymes, antioxidants, and B vitamins.
About 100 species of mushrooms are being studied for their health-promoting benefits, and about a half dozen really stand out for their ability to deliver a tremendous boost to your immune system. Studies have shown that mushrooms can combat infectious disease (including smallpox), inflammation, cancer and even help regenerate nerves. A compound from the Coriolus versicolor mushroom was recently found to significantly slow hemangiosarcoma in dogs, a deadly cancer.
Mushrooms are also nature’s recycling system, according to mycologist Paul Stamets. Various mushrooms can break down the toxins in nerve gas and clean up petroleum waste.
Mushrooms and their parent mycelium break down rocks and organic matter, turning them into soil. The mycelia, just like the mycorrhizal network, occupy landscapes in a web-like mat that, in some cases, stretches across thousands of acres. Stamets describes this intricate, branching network as “the Earth’s Internet” because it functions as a complex communication highway. There is also evidence mycelia are “sentient” beings that demonstrate the ability to learn. Speaking of cool and calculating…
Tips for Adding Mycorrhizae to Your Own Garden
Now that the secret’s out, companies are beginning to offer mycorrhizae to home gardeners and commercial farmers alike. If you have an organic garden, adding a sprinkle of mycorrhizae, along with good organic fertilizer, is a great way to ensure your garden will be the envy of your neighborhood.
For tips on how to use this in your garden at home, I recommend watching the “smiling gardener” video above. It’s important to remember that mycorrhizae must be applied to the roots of your plants. If you just sprinkle the granules onto the soil and they don’t make contact with the roots within about 48 hours, they’ll die and your efforts will be wasted. So, you can make a “tea” out of it and apply it as a spray, or you can rub a small amount directly onto the roots of your transplant. But it has to come into direct contact with some part of the root.
The only vegetable garden occupants that will not benefit from mycorrhizae are your brassicas (members of the mustard family, such as cabbage, broccoli, cauliflower, turnips, radishes, etc.), because they don’t allow this colonization.8 But all your other veggies will love you for it. The benefits will be even greater in a year or two, after the mycorrhizae really have a chance to grow and spread.
Also, remember to refrain from tilling and manipulating the soil. This isn’t necessary and is actually counterproductive, as it disrupts helpful organisms and crushes their tunnels.9 Just topdress your garden with a blend of good compost and topsoil each year, and leave the bed alone, which will allow those beneficial organisms to grow and flourish, undisturbed.
When you practice ecofriendly gardening, you greatly lessen your need for fertilizers and herbicides, reduce your need for watering, and reduce runoff and erosion, while giving your garden plants the best nutrition and resistance to disease. And best of all, a healthy veggie garden means more nutrients passed along to you!
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