Just discovered that fungus gnats are feasting on the roots of many of my cuttings.  I'm heading to HD this morning for some Bacillus thuringiensis. 

Nothing is sadder than anticipating cuttings to grow and thrive only to discover gnat larvae are systematically eating their little roots!

I know the BT works, and this morning I read that 1 part peroxide to 4 parts water kills the larvae on contact.  Of course, I'm out of that, so I'm going to pick some of that up too!

Any other solutions I'm missing?
Suzi

what does fungus gnats look like? i don't see any tiny flies around my trees, but i might be missing something.

They are very tiny and they like damp shade, so the cutting growing medium is perfect for them to breed.  I faced this problem a couple years ago with grape cuttings, and lost 2/3 of my cuttings.  Wiser now, I see those flying gnats, and I get right on them!  I put a few pots in partial shade, hoping the sun will dry out the top and discourage them till I can get to Home Depot. 

The year of the lost grapevines was memorable.  Hard lesson learned.  My grapes were all so green and pretty, then they started to die...  And I noticed all these gnats.  Found out the hard way about these critters.

I read all the time here about members who's cuttings had leafed out, and then died.  It's possible there just weren't roots, but also possible somebody is feasting on the roots too!  If you see tiny gnats around your pots, they lay hundreds of eggs in the damp soil, and the larvae make short work of any roots they encounter.

Suzi

Suzi, how do you apply the peroxide and water solution, in regular watering into the soil?  And does it work as well as  ?
thanks

I am sorry, but I've never done the peroxide thing.  Read about it this morning looking for another solution because I'm out of BT.

You are supposed to let the top inch dry out and then water the soil with it as you regularly do.

That's the same thing you do with BT.  Mix it in and spray on the leaves and use it to water the soil.

I may just alternate the two methods. 

Suzi

ok thanks suzi, I do see a few gnats flying around my cuttings guess I'll have to do the same as you.
thanks again.

If you have gnats and are loosing cuttings, it's most likely that your growing medium is too wet. Water less and you'll not only have fewer gnats, but also loose fewer cuttings. Most cuttings tend to root better with less water anyway. Dilute Hydrogen Peroxide application might kill some gnat larvae, but pouring on that will only make the rooting mix even wetter, and you'll lose even more cuttings.  The gnats may be a nuisance, but they are not what is killing most of your cuttings - they prefer eating dead matter like potting mix and compost. Any roots they might eat (which isn't often) are likely right at the soil surface.

I haven't watered for at least a month!  Finally yesterday I did, and that's when I noticed all those gnats.  The soil was almost dry, and the pots were very light.  They are no longer in the house, but outside in partial sun/shade under the grapevine canopy.  Trust me, they DO eat roots!

They will eat a slice of potato too!  Sometimes people let a potato slice lay on the top of the dirt, and when they lift it up after a day, lots of larvae munching under there.

Suzi

I've also read that those Mosquito rings that you float in ponds will kill off fungus gnats.  I think you make a dilute watering solution with these Mosquito rings, and soak the soil.  I think they contain BT.

Please do the research, I read about this a long time ago.  Maybe forum members will know more about this method.

These gnats are the biggest pain in the butt!  Before I knew what they were, I thought I had a fruit-fly infestation, and threw away all my fruit, for weeks, thinking I was bringing in new fly with each batch of new fruit.  They fly right in your nose, face, and eyes while you're watching TV!  They were infesting some potted Clivia that were growing in my house.  Too much moisture and organic matter in the soil, makes a perfect breeding environment.

Frank

This past spring I had some of the gnats around my cuttings, was concerned too, so read up on them. Yes, they will eat roots, but only those that have already died, or as mentioned above, those just at the soil surface. If you are using all perlite however, they'll go after anything organic they can find.

I also had read about the potato trick, thought that a cool idea, and tried it out of curiosity. After a week or more, that didn't attract a single larva. I was kind of disappointed and had wanted to watch some. In the end, I didn't have that many gnats so decided to ignore them, mist less, and from what I could see, they ended up doing no harm to my cuttings.

The cuttings I have going now I'm using even less moisture and have yet to see a gnat. But maybe I've just been lucky.

Good luck. It's not easy to watching plants having difficulties.

A related question:  Will fungus gnat larvae eat the roots of healthy growing fig trees too?  I mean not brand new cuttings, but say, a fig tree that's been up-potted and growing well in soil for many months.  Or is it just those tender "new cutting roots" that they'll eat?

Mike   central NY state, zone 5

I was told by the entomologist at VA Tech to just use very warm water when watering. It worked well for me.

Well, I am going to mix my Thuricide (BT from Home Depot) with warm water!  I'll do ANYTHING to kill these critters, but not harm my figs!

Wish you would have posted that before I went to Home Depot, but it's nice to know for future, and will probably help others.

Baby Bottle warm?  Or Warmer?

Thanks for the tip!

Suzi

Did the BT work?   I have new fig from Ebay dying.  Only cause I can see might be them gnats. Down to two leaves that are wilted.  Anything else to do? I repotted in new soil and not too wet but not doing well.  

Yes the BT worked. I used Thuricide from Home Depot.  No more gnats!  I did spray everything and water with the peroxide solution also.  After I sprayed, I used what was left to water.  Alternated them every other day.  My soil is well drained, and it is warm here.  They are outside in shade.    Good luck!
Suzi
When you re-potted did you see roots? 

they it was rooted.  Ihope it sprouts a new bud.  Going to get some of that.

Suzi I am so frusterated from the fungus which eats the roots of my vegetables when the cucumber tree is lush green and has beautiful flowers and starting to produce little ones it dies same thing happen to the zuccinni. I tried fungicide and nothing worked.I am so frusterated I  decided to grow cumcumber in pots. I am going to use your idea and drench the soil with this solution. 

Hi Suzi,
You may want to try covering soil surface with a layer of sand.  It works for many people.  :)  

Scott,  You are correct  the gnats don't like to lay their eggs in dry sand or crushed rock.  I forgot about that option!  Last year I doused everything with Thuricide THEN used crushed granite (which I have on hand because it goes into my soil mix).

Thuricide is safe for fruits and vegetables and it says right on the label how much to use per gallon.  NOT much!  It lasts a long time, you use so little.  It also kills the dreaded green horned tomato worm!  I noticed an entire cane of one of my grapevines was stripped of it's leaves in one night.  I discovered this big fat dude (exactly matching the leaves), and he fried on the 107 degree street pavement.  I then got all his siblings with the Thuricide!

We are all in this war together! :-))
Suzi

Here's a link about dryer sheets to repel fungus gnats.

http://www.gpnmag.com/repelling-fungus-gnats-dryer-sheets

Wow!  Who knew?  Nice link!

So to sum it up these are the solutions we've got so far:
1.  Thuricide BT
2.  Solution of 1-4, Peroxide and Water
3.  Very Warm water
4.  Layer of sand or crushed gravel on top
5.  Fresh Sheets of Bounce

Suzi

:-))  Noss, only thing that will kill those spider mites is a good dose of water, sprayed hard!!
Suzi

Noss you are right I have million spiders around my house and they eating tons of bugs they are good helpers. The only thing I dislike the spider wep sticking to my head. Hay better than those lousy bugs.