Gnatty dread

No matter the season, something always landed in my wine. In summer it was fruit flies and in winter it was fungus gnats.

That took a little while to figure out. Plants overwintering in the breakfast nook would, by December, be home to generations of scrawny flying insects. These were not apparent on the soil but only in the air, your face or your adult beverage.

Especially attracted to fungal odors such as those of beer or wine yeast, fungus gnats constitute six of the seven families categorized in Sciaroidea. I couldn't tell whether the ones breeding in my katuk plants were the same as those that infested my lemongrass back east, but I knew what to do about them when they turned up.

That discovery had been accidental. While living in a former industrial park, I had run a sprouter the size of an underbed shoebox to grow microgreens: alfalfa, radish, cabbage, lentil, peas, etc. The drain water had smelled quite fecund, so I tried it on the habanero peppers I grew in the window. They did great, and never suffered from gnats.

While reading about damping-off of seedlings (in which they are sapped by mold toxins and collapse), I found that certain plants are more resistant to it. Their seed coats contain naturally occurring fungicides that prevent the water mold Pythium from growing in the soil. I also learned that fungus gnats are a vector for Pythium, infecting soils with it via spores on their feet.

That would be terrible if you were starting seedlings indoors with your overwintering plants. I guessed that organisms similar to Pythium might be feeding the fungus gnats, so I started up the sprouter again in order to produce that precious stink-water. Sure enough: Within three days of starting a sprout water regime, all my fungus gnats vanished.

When fungus gnats appeared this winter, I didn't have the sprouter or seeds. Lentils, if certified organic (these are more likely to be alive, viable seed), would suffice. The sprouted lentils could then be sprinkled raw on a salad or toasted first for extra crunch.

While waiting the three days' interval for sprouted lentils, I scraped an inch of soil from the surface of the affected plants. Reasoning that healthy compost would contain predators of fungus gnat larvae, I replaced that inch of soil with my own compost.

Even before the lentils had finished sprouting, the fungus gnats disappeared. Once again, fertilizing plants organically also suppresses pathogens.

There are other, less holistic ways to control fungus gnat larvae. Greenhouses often use diflubenzuron which, like all -cides, kills much more than the target organism.

I've read about other methods that don't stray from permaculture principles. A sprinkling of diatomaceous earth may work, in the unlikely event you have that on hand. A layer of sand over the tops of potted plants' soil should separate the gnats from the decaying organic material on which they reproduce and feed.

Sprout-water and compost offer the largest array of benefits and feed the soil food web in potted plants. Whatever helps the most, helps best!

■ Alex Féthière has lived on Harstine Island long enough to forget New York City, where he built community gardens and double-dug his suburban sod into a victory garden. He can be reached at [email protected].