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Grow Q&A: Fungus Gnats

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Dear Dan,
How do I get rid of fungus gnats? – SOS (aka Sick of Swatting)

Dear SOS,
These small black flies are truly annoying and can prove to be expensive over time. Along with being almost impossible to catch in the air, their larvae feed on plant roots causing damage to the plant if left unchecked. Their presence is also a surefire indicator of over-watering.

Yellow sticky traps will help control the problem. The gnats are attracted to the yellow color and many of the already flying mature ones will end up stuck to the traps when hung at plant level. To get rid of the younger larvae, drench the soil with a biological larvicide such as Gnatrol twice weekly for one month in conjunction with a diluted neem oil spraying of your soil mix surface. Their life cycle is less than eight days, so you should be rid of them shortly.

The best way to avoid the problem of fungus gnats altogether is to not provide a comfortable home for the little buggers. They prefer the top layer of your pots to be moist and warm. Instead, bottom feed your plants using a wick system or purchase some self-watering containers specially made to water from below. The plant roots will pull up only what they need and the top layer will be much less desirable real estate for fungus gnats to move in and lay their eggs.

Have a grow question? Ask away at deardanko@hightimes.com

(Photo by @dannydanko)

 

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