Allotment Gardening Advice Help Chat

Growing => General Gardening => Topic started by: bendipa on May 29, 2012, 20:40

Title: Fungus gnats
Post by: bendipa on May 29, 2012, 20:40
Has anyone been plagued by these little black flies whick look like small mosquitos? They lay their eggs in soil, usually in pots and containers. The hatched translucent larvae, which are tiny then chew up the roots of plants, that eventually succumb. Young plants are particularly vulnerable and I've lost a number of these in recent weeks.

Anyone had this problem past or present and successfully found a way of getting rid of these pests?
Title: Re: Fungus gnats
Post by: Yorkie on May 29, 2012, 20:55
They are most common when the compost is too moist.

You can get nematodes I think, but have a look at a garden centre for an insecticide too.  Their botanical name is the sciarid fly.

You could also try replacing the compost but make sure you do it thoroughly.
Title: Re: Fungus gnats
Post by: sunshineband on May 29, 2012, 21:26
I just gave the surface of the compost a squirt with Provado ultimate bug killer as I had some to hand in the greenhouse  -- seems to have done for them  :nowink:
Title: Re: Fungus gnats
Post by: chrissie B on May 30, 2012, 09:41
another qestion answered i have these as well so thy bight because after digging a load of compost i had a number of bited on my legs , so far not had any plant damage not wanting to use chemicals is there another soltion
chrissie b
Title: Re: Fungus gnats
Post by: bendipa on May 30, 2012, 11:53
They are most common when the compost is too moist.

You can get nematodes I think, but have a look at a garden centre for an insecticide too.  Their botanical name is the sciarid fly.

You could also try replacing the compost but make sure you do it thoroughly.
Although the problem originally occurred with old compost, I had opened a new bag of compost, used it to fill pots and put some new plants in, then watered in. Within 24 hours all the pots were infested You say don't let the soil get moist, but you have to water in in the first place, The flies are then attracted to the soil.
Title: Re: Fungus gnats
Post by: Yorkie on May 30, 2012, 22:01
Although the problem originally occurred with old compost, I had opened a new bag of compost, used it to fill pots and put some new plants in, then watered in. Within 24 hours all the pots were infested You say don't let the soil get moist, but you have to water in in the first place, The flies are then attracted to the soil.

I doubt the flies were attracted to the soil in the space of 24 hours.

Far more probable that they were retained on / transferred from the existing infected compost around the roots of the plants, or already in the new compost.

Normal watering doesn't attract them - it's usually compost which is overmoist for periods of time.