Living Columns & Blogs

Smut City

I’m living in what used to be the smut capital of the nation.

I’m not talking about dirty pictures, but about the fungi that plague cereal plants like wheat. The fungi are known as “smut,” and they were once rife in the Pacific Northwest. The good news is that smut is mostly under control these days owing to long-term efforts by plant pathologists.

Some fungi can grow on wheat, and other fungi can grow in your toenails. Smut fungi in wheat can be eradicated by pesticides while plants thrive relatively unaffected by the poisons. It’s tougher to eliminate fungi that live in toenails, because fungi are more like us animals than they are like plants – which means it’s difficult to eradicate toenail fungus without damaging some of your own cells.

Fungi get their revenge on us for our pesticides by polishing off a few people from time to time. Novice mushroom pickers sometimes make the news when they die from toxins in fungi. And a simple by-product of fungi called aflatoxin sickens many animals. Aflatoxin can be found in corn and peanuts, particularly when they are stored for a time.

Recently in the U.S. aflatoxin killed a number of dogs and cats because it was in pet food, introduced accidentally into the vegetable part of the formulation. The good news for us is that food destined for humans is tested for aflatoxin.

“Aflatoxin is really bad stuff, and it’s a potent cancer-causing agent,” said Washington State University plant pathology professor Jack Rogers to me one recent morning.

The aflatoxin isn’t something the fungi itself needs.

“But the fungi may have evolved to produce the aflatoxin to keep us animals away,” explained WSU plant pathology professor Lori Carris.

The two professors explained the basics of smut and aflatoxin when they gave me a tour of the fungus herbarium at WSU. There are samples of 71,521 species of all sorts of fungi including common and exotic mushrooms, a wide range of smut, and more.

Here’s what I think is the very best part of the fungal story I learned from the professors:

There was a time in Earth’s history when fungi were the most impressive life forms on land. That’s a tale both fungus experts and geologists love.

Back long before the saber tooth tiger and the woolly mammoth, and even before the age of the dinosaurs, the living world was a very different place.

Land plants were humble, lichen-like vegetation, only a couple of inches tall. The simple plants had no roots and no leaves. Land animals back in that day were all but nonexistent, likely limited to a few insect species.

Geologists call that time the earliest part of the Devonian Period. The name is from Devonshire, in Great Britain, where we first discovered rocks of that age. (Geologists generally name periods of time for places. We’re an odd tribe.)

What appear to be Devonian fungi are preserved in what became flint-like rock. Fungal experts have recently studied these fossils in all their odd glory.

Remember the idea that fungi are more like us animals than they are like plants? That’s part of the way to make sense of the possibility of giant fungi of the ancient past, living off the hard work of the simple vegetation of the time.

To make a living, fungi must consume things, just like us animals. Compared to a pouncing cougar, fungi are slow moving. But they can reach out and touch the world around them. Fungal threads secrete enzymes that dissolve organic material. This altered material is absorbed by the fungus as its food.

That means the Devonian giant fungi were, so to speak, the top “predators” of their day, feasting on the poor little plants.

But, I hasten to add, the scientific jury verdict isn’t fully in yet on the Devonian. There are just a few fossils of the type in question, and they can be interpreted in different ways.

Still, there’s a real chance that fungi were once Lord of the Jungle -- a fact that could be powerful fuel for nightmares if you meditate on the Devonian as you fall asleep.

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