Fungus gnats

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abax

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I have used Gnatrol four times according to directions on the bag. I'm still seeing fungus gnats on
my yellow sticky traps. Anybody got any suggestions about an alternate application? I'd appreciate
just about anything that will get rid of the damn things.
 

eds

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I don't know if they're available on your side of the Atlantic or how well they'd work in a very open orchid media but I nobbled a very irritating infestation of them in some large pots in my office using sticky traps and nematodes watered into the media. I used them twice a few months apart and the traps are now clear of any gnats.
 

Ray

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Angela.

Gnatrol only kills the larvae. What dosing interval did you use?

I don't know what the label says about frequency of thorough media drenching, but according to an article from the Missouri Botanical Garden, "the larvae feed for about 2 weeks and then pupate near the soil surface within thread chambers. After 3 to 7 days in the pupal stage, adults emerge and live for about 8 days. The gnats develop from egg to adult in 3 to 4 weeks. Their life cycle is dependent on temperature. The developmental time increases as temperature decreases." That suggested top me that 4 treatments at one-week intervals would be a bare minimum.

I had some gnat issues with my plants in late winter, so watered them twice in a row (about 1 week apart) with "mosquito dunk water", and haven't seen one since.
 

abax

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Ray, I used Gnatrol at 7 day intervals as a drench at three tablespoons per gallon for
four weeks. Please enlighten me about where to get mosquito dunks and how much to
use per gallon of water. I'm not at all familiar with the product or where to get it.
Thank you eds and Ray.
 

Ray

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Mosquito Dunks are a product from Summit that look like little floating doughnuts. They contain cultures of the same bacterium as Gnatrol, and are intended to be thrown into ponds to kill mosquito larvae.

I just break them up into 4 or 5 pieces, drop them into a container of water and wait a few days for the population to take off, then use the liquid to water the plants.

There is a sister product, Mosquito Bits, that’s already granular, so probably “activates” more quickly.

Almost any hardware store carries them down here.
 

abax

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Thank you Ray. Since I use 7 gals. of water in a Spot Shot per watering, I'm
concerned with over-doing the dunks.

SkyBear, I did grow insectivorous plants many years ago and enjoyed them enormously.
I don't think little sundews can handle the damn gnats in my greenhouse...poor babies
would choke on the excess!
"
 

Ray

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Angela, I don’t know how you’d overdo it. The bacteria does absolutely nothing to the plants.

if you have any damp places with accumulated organic matter or moss, they could be in there, too.
 

Sky7Bear

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Thank you Ray. Since I use 7 gals. of water in a Spot Shot per watering, I'm
concerned with over-doing the dunks.

SkyBear, I did grow insectivorous plants many years ago and enjoyed them enormously.
I don't think little sundews can handle the damn gnats in my greenhouse...poor babies
would choke on the excess!
"
Thank you Ray. Since I use 7 gals. of water in a Spot Shot per watering, I'm
concerned with over-doing the dunks.

SkyBear, I did grow insectivorous plants many years ago and enjoyed them enormously.
I don't think little sundews can handle the damn gnats in my greenhouse...poor babies
would choke on the excess!
"
Sundews aren't the only option, of course. Get more plants may be called for, at least until balance is restored.
 

SEMO-Cypr

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I would add a few carnivorous plants, my go to for gnat control are Pinguicula.. if you have a lot get a P. Gigantea if you got the room or just a Moranensis. They are very easy to propogate so you once started you can just keep adding more plants and moving them around. They are very easy to care for in my experience.
 

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SEMO-Cypr

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Some Pings grow on the side of trees in nature so you could technically add them to mounts... 🤪. But now I’m just being a smart ass.

But the chemical route and mosquito dunks probably the best option as mentioned above.
 
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