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Deering, NH

Hi All,
Very small gnats have appeared on the leaves for the first time ever. I suspect they are fungus gnats. Any thoughts or experiences with this swarm? Should they be a concern and what to do about them? Your help is greatly appreciated.

9/4/2022 7:20:00 PM

Bethlehem CT

Are you sure that they aren't whiteflies, fungus gnats are usually a greenhouse problem. If they are fungus gnats it is a sign of too much moisture in the soil. They thrive on slimy type of conditions from too much water in (usually) a potting mix. Adult fungus gnats are not what cause the damage, the larva feed on the roots and can open the plants (usually seedlings) to disease. Th fungus gnat can be controlled culturally by making sure to let things dry down a bit between waterings. An imidacloprid drench would probably take care of them and or whiteflies. Any contact insecticide (like permethrin) should work if the problem is whiteflies or just about anything (besides mites) for that matter..

9/5/2022 7:48:45 AM

Deering, NH

Thanks Big Moon! These black gnat like pests are in the thousands on top of the leaves and not underneath. Never had them in years past. White flies were around a few weeks ago and taken care of with Talstar and Merit. Yes the ground is wet due to the drip lines. Any other thoughts are welcomed?

9/5/2022 8:59:19 AM

Deering, NH

I found this interesting test to determine if I have fungus gnats.
​If you want to confirm that you have fungus gnat larvae, use slices of potato. ​Larvae are attracted to potatoes​, and they’ll leave the soil to feed on it. ​

Slice a potato into thin slices and leave them on top of the soil line.
Wait 2 to 3 days.
Check your potato slices for larvae. They look like tiny, moving seeds with black heads.
Throw the infested potato slices away.
​​If you discover larvae, use the prevention and control methods​ below to get rid of them.

9/5/2022 9:24:01 AM