There’s absolutely no reason to believe that anybody reading this reads Greenhouse Product News magazine, unless you’re running your own commercial nursery. For those who do, GPN is a free trade publication that offers US and international subscriptions, covering new developments in propagation and distribution for greenhouse operators. And for everybody else, it’s one of the magazines I read cover-to-cover when I get each issue.
Okay, so you’re figuring “Yeah, but you’ll read anything.” That’s all too true: when left without sufficient reading material, I’ve been known to memorize guides for wallpaper application and removal. (The summer of 1976 is one I don’t want to repeat, EVER.) However, you won’t believe some of the interesting stuff you’ll come across in an issue. Case in point, I just received the July 2011 issue Saturday, and immediately glommed onto the subhead cover story “Can Dryer Sheets Repel Fungus Gnats?” Sadly, the article isn’t online yet, so let me give a synopsis for the fungus-gnat-impaired.
Every spring, I get calls from friends, cohorts, and co-workers at the Day Job, getting frantic about little black bugs that fly errratically around flowerpots and other soil-bearing containers. I explain, over and over, that these are fungus gnats. The most common genus in my vicinity, Bradysia, is completely harmless to humans, even if they are annoying. The grubs are pests when they eat the roots of potted plants, but the whole life cycle is so rapid that they’re rarely a pest for more than two or three weeks. In my case, I don’t complain, because the fungus gnats start up in my greenhouse right about the time all of my temperate sundews and butterworts come out of dormancy. Set out a few Pinguicula primulflora, which attract fungus gnats like a “FREE BEER” sign attracts fratboys, and the butterworts feed exceedingly well.
What’s a minor annoyance in a small greenhouse, though, can be a major disaster in a commercial operation, especially when the little vermin feed on particularly delicate roots of plants that can’t handle the attention. Commercial operations have many different ways to control fungus gnat onslaughts, and one of the more intriguing involved using fabric softener dryer sheets to repel them.
Want to know why I love GPN? It’s because the article starts “In fact, Bounce original brand fabric softener dryer sheets have been promoted to repel mosquitoes and ‘gnats’ in some magazines; however, there is no quantitative data to substantiate such claims.” The four authors (Raymond A. Cloyd, Karen A. Marley, Richard A. Larson, and Bari Arieli) then supply the quantitative data. Contrary to a lot of claims about homespun garden cures (*coughSuperThrivecough*), this apparently really works in laboratory experiments.
According to the paper, one of the major volatile constituents in the dryer sheets is a monoterpene alcohol called linalool, which is also used in cosmetics, apparently is the active ingredient in the fungus gnat repellent. Interestingly, the citrosa plant Pelagornium citrosum, commonly hyped as a mosquito repellent with only a small amount of data to back up those claims, is loaded with linalool.
Now, this leads to all sorts of interesting possibilities. The first is that enterprising young horticulture students should consider further research into linalool as a fungus gnat repellent, and possibly develop an improved delivery system over fabric softener sheets. The second is possibly a further evaluation of linalool as a mosquito repellent. The best one, though, is that when co-workers start nuhdzing about fungus gnats every spring, I’m going to their pots with a teddy bear and scream “The fungus gnats will die before my eyes, and they’ll know – THEY’LL KNOW – that it is I, Baron Snuggles, who encompasses their doom!” That should take care of the problem once and for all. (Hey, it worked when they were bugging me about dog’s vomit slime mold in their flowerbeds.)