Garden Q&A: Fungi are everywhere, and they're not all to be feared

Garden Q&A: Fungi are everywhere, and they're not all to be feared
Maybe it’s all coincidence. Maybe it’s the mild and damp air at this time of year. Maybe it’s just part of the newfound interest in the subject of mycology. But whatever the reason, recently there seem to be a lot of articles and lectures and even a Netflix documentary about fungi. Not just the kind that menace our plants, nor the ones we saute, but the broad, complicated science surrounding their study, which is called mycology.
Fungi are neither plants nor animals (though DNA studies have determined that fungi and people are more closely “related” than fungi and plants). They make up their own kingdom that includes yeasts, rusts, smuts, mildews, molds and, of course, mushrooms. They are among the most widely spread organisms on earth and are proving to potentially be of great environmental and medical importance.
They are also one of, if not the, oldest continuing life form on the planet. In 2020, a group of researchers identified a fungal fossil dating back at least 715 million years or more. That means fungi in some form predate land plants that didn’t come onto the scene until about 300 million years ago and have survived six mass extinction events over the past 445 million years.
Fungi, together with bacteria, are responsible for most of the recycling on the planet, by turning biomass into soil. They recycle dead organic matter back into organic material in a form which can be reused. Without fungi, this recycling would be seriously slowed, leaving us lost under piles of thick, dead plant and animal parts.
Humans seem to have a love-repulsion-fear relationship with fungi. In part because of their obvious association with death and rotting.
Possibly in part because they are fearful of ingesting mushrooms that we know may be deadly. In reality, though, only about 1% of the known species is lethal.
Some folks are anxious because they’ve have heard too much about (or even experienced) the psychoactive properties of some mushrooms. Who hasn’t heard of “magic mushrooms” and Timothy Leary?
Some people may be creeped out by the way mushrooms and toadstools, the fruiting, parts of fungi, appear overnight and disappear just as mysteriously. They are the reproductive structures of the larger underground organism. The spores are released above ground to float or swim away from the parent.
True. Some mushrooms and other fungi will make you sick. But others have provided life-saving medicines. Perhaps the most famous of all antibiotic drugs, and one of the world’s first, penicillin, is derived from a common fungus called Penicillium. Since that accidental discovery in 1928, many other antibiotics are now widely used to control diseases in human and animal populations. The discovery of the action of this one organism revolutionized world health care.
And other mushrooms are just plain delicious. So delicious in fact that the American diet includes more than it used to — about four pounds per person per year. But that represents only a small portion of the fungi we actually consume. More often, we’ll find fungi used in the production of many foods and drinks, such as cheeses, beer, wine, bread, cakes and other products.
We began this column explaining that fungi are all around us. While mushrooms and toadstools may be the attention getters of the fungi kingdom, the real action is taking place underfoot. As of 2020, almost 150,000 species of fungi have been identified, but the global number of species can only be guessed. A 2017 report suggests that this may be only 10% of estimated 2.2 million species worldwide.
Most fungi are inconspicuous because of the small size of their structures. Most fungi are multicellular. Most form tiny microscopic cylindrical threads, from which hyphal tips branch out in all directions. This gossamer-like underground network is known as mycelium. This network can extend for miles. The largest living organism on earth today is a fungus in Oregon just beneath the surface of the ground, covering about 3.7 square miles and estimated to weigh as much as thirty-five thousand tons.
Most, but not all, fungi reproduce by spores — “a reproductive cell capable of developing into a new individual without fusion with another reproductive cell.” Spores can sit inactive for long periods prior to germination, which will only occur when the environment is conducive. Other species, like yeast and penicillin and some other molds, never make a fruiting body at all.
Unlike plants, fungi don’t have chlorophyll and can’t photosynthesize. Instead, they must rely on once-living matter. They feed on what organic material their hyphal tips bumps into, be it the remains of a giant oak, a tiny field mouse or a piece of bread. The spores expelled by the fruiting structure will secrete enzymes to digest food outside of their bodies which they then absorb.
For the home gardener, the word “fungus” strikes dread into our marrow. After all, they are the cause of about 85% of all plant diseases. From black spot, powdery mildew, cercospora leaf spot, take all root rot, to anthracnose, a fungus will be the cause. Once active, fungal diseases exploit plant weaknesses, leaving plants prone to more disease and insect pests. The UF publication, “Fungi and Plant Disease” provides a more detailed discussion of these problems with links to solutions: (https://gardeningsolutions.ifas.ufl.edu/care/pests-and-diseases/diseases/fungi-and-plant-disease.html).
Perhaps a quote from Merlin Sheldrake, noted author on mycology, offers some reason for the spreading interest in fungi: “… they are humble yet astonishingly versatile organisms, eating rock, making soil … nourishing and killing plants … inducing visions, producing food, making medicines … and influencing the composition of the earth’s atmosphere.”
I can’t help but think … that’s not a bad day’s work.
Paula Weatherby is a Master Gardener Volunteer with the Duval County Extension Service and the University of Florida/IFAS. For gardening questions, call the Duval County Extension Office at (904) 255-7450 from 9 a.m. to noon and 12:30 to 3:30 p.m. Monday-Friday and ask for a Master Gardener Volunteer.