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+--- Thread: Fungus Gnats (/showthread.php?tid=920)
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Fungus Gnats - PyreneesPlot - 05-03-2021
I have a massive outbreak of these pests amongst my seedlings this year, despite keeping the compost frighteningly dry and only watering from below.
Given that each female can lay 200 eggs I'm wondering if I should try and repot as many as possible to try and limit the damage?
I also have some pyrethrum based insecticide (for cat fleas etc) which I'm contemplating diluting and using as a drench or spray. Although organic, I'm not happy about doing that, but at the moment all chillies, peppers & aubergines are infested.
Nightmare
Any thoughts would be much appreciated.
RE: Fungus Gnats - Can the Man - 05-03-2021
(05-03-2021, 10:30 PM)PyreneesPlot Wrote: I have a massive outbreak of these pests amongst my seedlings this year, despite keeping the compost frighteningly dry and only watering from below.Oh PP sounds terrible, I’d try the insecticide approach. Best of luck.
Given that each female can lay 200 eggs I'm wondering if I should try and repot as many as possible to try and limit the damage?
I also have some pyrethrum based insecticide (for cat fleas etc) which I'm contemplating diluting and using as a drench or spray. Although organic, I'm not happy about doing that, but at the moment all chillies, peppers & aubergines are infested.
Nightmare
Any thoughts would be much appreciated.
RE: Fungus Gnats - Small chilli - 05-03-2021
I’m having a problem with them as well. Never had a problem before so can’t help. But will be watching reply’s for ideas what to do!
RE: Fungus Gnats - toomanytommytoes - 05-03-2021
Yellow sticky traps are good. Only kills the adults of course, but eventually will get rid of them. I only use them indoors as even in the greenhouse they can kills spiders and other friendly bugs. I've also used predatory mites with good success, but don't know if they are available where you are. This is what I used - https://www.dragonfli.co.uk/collections/fungus-fly/products/predatory-mite-hypoaspis-miles
There's also a strain of nematodes which kills the larvae, again not sure if it's available where you are.
If you need something more instant I'd just use the pyrethrum, it kills the adults and larvae, and at this time of year there shouldn't be collateral damage to other insects.
RE: Fungus Gnats - toomanytommytoes - 05-03-2021
'Mosquito dunks' also kill the larvae. They contain a strain of bacteria similar to the one used to control caterpillars.
RE: Fungus Gnats - mcdood - 06-03-2021
One year I tried vinegar and oil traps, layer of sand, diatomaceous earth, sticky tape. Sticky tape was probably the most effective of those for keeping numbers down but didnt get rid and was messy. It's a pain but the organic method that worked for me was a layer of grit over the top of every pot, tray or module in the area to stop them laying eggs in the first place
RE: Fungus Gnats - Moth - 06-03-2021
(06-03-2021, 02:14 AM)mcdood Wrote: One year I tried vinegar and oil traps, layer of sand, diatomaceous earth, sticky tape. Sticky tape was probably the most effective of those for keeping numbers down but didnt get rid and was messy. It's a pain but the organic method that worked for me was a layer of grit over the top of every pot, tray or module in the area to stop them laying eggs in the first place
That's what I do too. And stand the seed trays/pots on a layer of grit because they get under the bottom of the pots, pernicious little critters.
RE: Fungus Gnats - PyreneesPlot - 06-03-2021
Thanks everyone
I have some sticky tape set up which has so far caught none!! I'm a little anxious about using it and the spray because there are a few little zebra spiders hopping around amongst the pots.
I've used diatomaceous earth on other pests before, so may look at that, plus putting grit on top - I wonder if builder's sand would work as I have that to hand and grit is expensive?
I think predatory insects and nematodes are probably not worth the expense as this SHOULD be a short term problem with all the plants going in the ground outdoors in May, if not earlier.
I have to prick out some seedling aubergines today so I may sacrifice any spare for the good of science and see how they cope with the insecticide spray and a thin layer of sand.
The seedlings are all in our open plan living space so perhaps the most annoying thing is finding a gnat in your coffee or worse in your wine glass.
RE: Fungus Gnats - Spec - 06-03-2021
I use a garlic solution with a squirt of environmental friendly washing up liquid (it's been sitting in the greenhouse and lost its label) I spray this on any plants that have infestation problems, also use it on my cabbages as it keeps the snails off them
RE: Fungus Gnats - Scarlet - 06-03-2021
I'm with the layer of grit method along with sticky traps to get those that are flying.
I had a really bad infestation one year and I believe the grit made a huge difference - advised by Mcdood when I was trying to take dahlia cuttings - still trying by the way ;(