Throughout the first 7 weeks of veg, the 2x4 tent was kept closed with a 6 inch fan and exhaust/filter assembly running. After I flushed the plants to lower the PPM and raise the pH, the 3 gallon fabric pots were soaked. After a couple of days a white mold formed on the outside of the bags. I wiped off the mold, and kept the tent open, running a 30” tower fan from outside the tent. The bags dried quickly and the mold did not return. I close the tent up during the dark cycle.
Yesterday, I opened the tent up a saw a lone gnat flying around. I hung an adhesive bug strip. By the end of the day, it the gnat was stuck to the strip. Today, when opening the tent, there was another. I managed to squash and recover it. What is this thing and can I expect a larger population problem?
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I went out of town for 4 days, the tent stayed closed with two ceiling fans moving the leaves. Upon return, I checked the tack strips. The hanging strips were clean, but the strips lying on the soil has several very small immature gnats stuck to them. Over the past couple of weeks, I have only encountered 2 adults early on and exterminated both. It seems the nymphs emerge from the soil and go to the tack strips, interrupting the life/reproduction cycle. I put more tack strips on the soil to attract and capture whatever comes out..
Only caught four more small immature ones on hanging and soil topping tack strips over days. I dried the soil mix before using, so hopefully there won’t be too many more.
Don't panic; you should be able to get rid of them somewhat easily. I wrote a whole article on it which includes solutions. See here: https://www.mrgrowit.com/post/fungus-gnats-on-cannabis-plants
Thanks Cap…it’s been nine days since the flush and the bags are still heavy. I’m going to wait for them to be much lighter before adding any water.
I caught one of those buggers on my sticky trap two days ago. I plan to not worry about it.
If you get a major infestation then there are things you can get like Neem oil and diatomaceous earth, but for 1 Gnat to a minor infestation there a some simple things you can do to manage it.
Keep those sticky traps hanging up above and below the canopy and check them daily.
Let the soil dry out real good between watering and this will kill any larvae in the soil. The larvae is what damages the plant, not the flying adults.
Have a good air flow both above and especially below the canopy, so at least two fans going all the time. A fan blowing below the canopy helps stop the adults from laying eggs in the soil.
Finding a few gnats everyday is not a big deal as long as you keep on top of things. If your yellow sticky traps end up being completely covered with gnats, then you pull out the big guns.
Good luck!