Fungus Gnats on flowering plants in greenhouse

Hello, my name is Karen and I’m a beginner grower. I’m currently growing White Widow plant outdoors in a greenhouse. I’m having issues with fungus gnats, and my plants tips are brown. I’m not sure if the eggs from the gnats have infected my plant. I have purchased some SNS 209 and have been using it for about a week, but the tips of the leaves seem to have gotten darker. Please help, thanks.

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Hey Karen! Seems several issues going there. Fungus gnats will put larvae on your wet top soil. So you can let your top soil inches dry out and sprinkle diatomaceous earth. This should kill the larvae living in the soil and tackle mature ones.

I will tag you along expert users to assist you. @Covertgrower

@Cannabian is an outdoor guru! We missed you man :hugs:

However she is close to finish and she will I think.


I would also agree that she close to being chopped. I’m not familiar with you product, do you have p pictures of the bottle?

I see it has either pyrethrum or pryrethrin.Rum is good,Rin is not good for you to ingest


Looks really natural, but considering you’re so close to chopping, I would discontinue use at this point, just to safe guard any affect on terpenes. Any application of any product can make the leaves look odd, but you should be good to harvest.

Ok, thx I’ve only just watering them. When do you think I should harvest? I think the end of the month?
Also I have another White Widow, may I send you a pic of that?

I also gave it the same solution. Uploading: B4B13CFC-F8FA-483A-828C-42597C5F7659.jpeg…

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If you have a jewelers loupe to check trichome cooler it will help.
Otherwise harvest when all pistils are brown.

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Ok, thank you. Oh one last question for now.At this point should I give them any type of bloom nutrition ( I use fox farm)? Since one of my plants has brown? Or should I just start to flush them?

She looks close to done, however, you can stop fungas gnats by placing a 1/4 inch layer of really fine sand, or use diatomaceous earth. Your plant wont really benefit at this stage though, as its mostly finished. I get them too but my plants are so big it causes them very little harm. Another trick is to plant in a bigger pot. Water one time around the outer edge real slow to keep the center dry, and the next time water near the middle to keep th outside dry. Its the damp soil they thrive on. The sand prevents them from entering or leaving but it comes at a cost of less gas exchange to and from the soil.