Black Fungus Gnat – IPM Treatment
We all know what a gnat is. Most likely you have had a few gnats flying around your home, more commonly known as “fruit flies”. But fungus gnats are your gardens worst nightmare! They are small flies that infest soil and potting mix and lay their eggs in your container gardens as well. Their eggs can lay dormant in soil for weeks and then release these nasty little larvae that wreak havoc on your plants. Their larvae primarily feed on fungi and organic matter in soil, but also chew into roots and can be a problem in greenhouses, nurseries, potted plants and interior plants. Adult fungus gnats may emerge from houseplants and become a nuisance indoors too.
There are a bunch of organic and chemical treatments for fungus gnats. The organic solutions include:
Hydrogen peroxide w/ no additives, Boiled grapefruit rind, Neem oil and a plethora of IPM.
We discovered we had gnats in our indoor Sunglo greenhouse after purchasing a bag of store bought miracle soil. It has been a HUGE problem. At least 100 plants have been ruined. So we researched online and came to the conclusion that we would try nematodes.
What are nematodes?
The nematodes or roundworms constitute the phylum Nematoda. They are a diverse animal phylum inhabiting a very broad range of environments. Nematode species can be difficult to distinguish, and although over 25,000 have been described, of which more than half are parasitic, the total number of nematode species has been estimated to be about 1 million.Unlike cnidarians and flatworms, nematodes have tubular digestive systems with openings at both ends. Nematodes have successfully adapted to nearly every ecosystem from marine to fresh water, to soils, and from the polar regions to the tropics, as well as the highest to the lowest of elevations. They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in locations as diverse as mountains, deserts and oceanic trenches. The earth benefits from these microscopic worms. They are pretty much everywhere!
There are lots of brand of nematodes to buy but we settled on this baby. Above. The nematodes come wrapped in a soft wet sponge ready to swim their way into your soil and eat the fungus gnat larvae!
By dunking the sponge in water and swooshing it around a bit, it will release the microscopic nematodes into the water and allow them to be transferred into your infested soil. One they have broken the soil barrier the nematodes are free to wreak
havoc on the fungus gnat larvae! Too bad they are microscopic. It would be pretty neat to see
The nematode treatment worked, along with sticky tape but only for a week or so. It was difficult keeping our greenhouse contained. The gnats had too many places to hide in our building and were able to fly freely in and out of the greenhouse. In a different situation the nematodes, I’m sure, would have wiped out the larvae and our problem would have disappeared. We eventually cleaned out the entire greenhouse, cleaned all pots and containers, threw away all the dirt that was sitting around and moved most of the plants outside for a weekend to try to abolish the pesky gnats! And so far we’ve gotten rid of ALMOST all of them. The orchids we have in the greenhouse now are doing pretty well – See picture below. There are still a few gnats buzzing around but they have not harmed our orchid collection. We definitely learned a lesson from this… no more store bought generic soil! And to keep the greenhouse as clean as possible when planting seeds. The next time we see the first signs of gnats we’ll reach into our Google arsenal and find the next best treatment.