peroxide for fungus gnats?

[bower]

Has anyone used diluted peroxide as a soil drench to kill fungus gnat larvae?

My peppers want to be transplanted out and/or potted up larger, but I was hoping to clear up the infestation so I can keep a couple of plants in house.

Spraying the soil with neem/soap when they're hopping is a contact killer but not long term control.

If I use peroxide (or anything else?) I need to know how often to apply it to get the job done, once and for all... Or perhaps it is useless at this time of year, the gnats evidently get through my screens and although there's few adult flies ever seen, they seem to manage to get their party going in my pots every time.

[Labradors2]

Poor you! I have that problem in the winter when I am forced to buy certain potting mixes because it's out of season...

I've used peroxide and I think it helps a bit, along with the yellow stickies to catch the adults, trying to let the top layer of "soil" dry out, and watering from the bottom.

Last winter, I watered with peroxide once a week, which probably wasn't enough. Drying out that top layer is the best method.

As for not seeing them. I agree that there don't seem to be many adults. Then I find them dead in the bath which is a loooong way away from the plant-growing area. They are searching for water!

Good luck with the fight!

Linda

[bower]

Thanks for the advice, Linda. I was reading about the drainage and drying out as well - some people suggest a layer of dry stuff on top - like sand.

It's only this morning I finally identified this pest, to add to the list of 'no see ums' that bother my peppers as soon as spring rolls around and it's warm enough to open a window. These are the worst! And their time of attack is the worst too, as I'm just waiting for that first crop of peppers to ripen before I put them out.

Having 35 pepper plants in the house, there is way too much habitat for these nasties.

[Lorri D]

I have tried neem, peroxide, yellow sticky papers, pyrithrin, the vacuum and bowls of cider vinegar, nothing worked.

I use soil blocks, so the gnats could pretty much take over. Bottom watering was no help, being that they are open on all sides. I broke down and bought some gnatrol after lots of research one year for my flowers I was growing. I bought the gnatrol from amazon, 12$ for 80 (1 gal) applications. They say in a severe infestation it takes 3 applications.

I bought mites once that are a natural predators to the fungus gnats "hypoaspis miles", but they were expensive and weren't able to survive in my greenhouse all year. Lorri D

[bower]

Lorri D,
Thanks for the reality check...
I guess I should be prepared for the possibility that peroxide won't do any better than neem...
I'm seriously thinking I should try to find some finer mesh screens. Those little holes are suddenly looking pretty large.

So far I haven't seen fungus gnat troubles in my greenhouse (fingers crossed) - I don't know whether they like peppers better than tomatoes, or whether some gnat larvae predators are also resident in my greenhouse soils. Now that I think of it, I've had the same problem on tomatoes in the house too, at least when they're among the peppers.

I actually thought the pest must like dry soil, as it's so much dryer in the house. Oops.

[ChrisK]

Have you tried mosquito dunks or other products containing Bti?

[bower]

ChrisK, I was just reading about the mosquito dunks this morning. I'm not sure where to get them (haven't noticed them on the shelf here) but I'll look again.

It doesn't sound like the peroxide is any more effective than the neem/soap, ie temporary or needs repeat applications, and since it's mixed 1:4 with water that would amount to a boatload of peroxide and wouldn't be cost effective either.

It also seems like a losing battle at this time of year - so I'm pretty well resigned to having to put the peppers out for the summer. I think I'll give them a soapy dunk when I plant them out so there's no residue that might harm any beneficials out there.

But if I'm going to try bringing a couple of plants in for the winter, I will probably get the Bt product to clean them up for indoors.... thanks!

[kayrobbins]

I bought the mosquito bits instead of the dunks on Amazon. They are working really well for me.

[Heritage]

Bower,

You can find BTi, sold as "Gnatrol", at Amazon and Ebay. Just make sure it is a fairly fresh batch, and not something that has been sitting on the shelf for months. (same if you use the mosquito dunks).

Good luck!
Steve

[bower]

Still have some peppers in the house, waiting to be planted out, and I think I'le figured out something about the soap/neem method..
You have to let the soil dry out completely, then spray the soil surface and sides of the pot with the soap when the soil is dry. I did this and waited until the next day to water them - no sign of any hoppers in any of the pots with dry soil - only in one that was not completely dry.

Of course it's useless to have one infested pot around... the others will have em again in no time. But it gives me hope.... a small respite for the poor peppers to ripen.