Fungus Gnats and Seedlings

[Derkshaman]

The dreaded Fungus gnat...

a huge obstacle in certain climates, or especially when growing anything indoors.

Wreaking havoc on plants, taking their vigor or in the case of young, fragile plants... completely killing them.

Anyways, I've noticed that Fungus gnats are a real problem when growing cacti seedlings, at least for me.

They come and go, and luckily only a couple of my containers have been hit.

I'm especially anxious when they infest newly sowed seedlings.

How do my fellow SABers go about annihilating these pests?

I'm already some-what aware of how to prevent them... avoid letting the soil get too soggy (and perhaps cover the surface with sand?)

But sometimes they seem to pop up anyways, perhaps when the conditions are a little less than ideal... and it seems like once they're there, then keeping the soil a little dry is no longer effective.

I've taken them out in the past with some success using the biological insect weapon, Bacillus thuringiensis, or mosquito dunks.

I'm sometimes hesitant to water with the solution, simply for the reason that my seedling containers are already saturated and the seedlings seem very sensitive to a soggy medium.

It doesn't always seem to work 100%, but regardless, this is currently my best solution.

Just wondering what you all do to combat these pests. And how large of an impact they seem to be on cacti seedlings.

If I notice gnats, is it usually too late for my plants? In the case of young trichocereus seedlings.

I've heard of diatomaceous earth being used, but I fear this will mess up my soil's consistency.

Not aware of if any/which pesticides are suitable.

I have learned so much valuable information here (A special thanks to AZS in particular!) and am never surprised when someone points out an obvious inadequacy on my part.

Edited December 4, 2015 by Derkshaman

[Derkshaman]

I've also had an isolated case of springtails, only on one container. The seedlings have since been failing to thrive, and they frequently fall over with no sign of ever having a root! I have actually watched the incredibly tiny suckers gather around and munch on the seedlings. Luckily they have only occurred in one container in my time of growing seedlings- I assume this is just because of an unbalanced medium... but is any effective way to combat them?

[☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ]

use a secret weapon :3

on second thoughts don't use any ant that's not in your state or subject to legal control... if the advice in this forum thread is accurate

(from the american guy posting called lucian)

http://antfarm.yuku.com/reply/100823/Consequences-of-rearing-of-exotic-ant-species-

probably best to check your local rules and regs if you fancy beneficial ants

Edited December 4, 2015 by ☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ

[☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ]

or if it's cacti ,

use pure sand like the pros?

another secret weapon for older cacti if ever needed..

http://www.bonsai4me.co.uk/Basics/Basicscatlitter.htm

oh yeah , not to forget coco coir too

my research beginning in an aquatic life ventures always saw springtails being advised as beneficial

(usually to pet frog owners with real live terrarium/vivarium plants like mosses and such)..

I didn't realise they were that detrimental .. I guess they're probably more beneficial for sprouting samaras like aya n such..

how about....

... microwave tek and hermetically sealed single cells?

Edited December 3, 2015 by ☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ

[Kykeion]

Gnatrol is what I use. I have not had much issue with them in the past, only occasionally finding them in house plants, and never to a detrimental level. Several months ago I noticed some in my cacti and other seedlings so I bought some of this (i think I found it on amazon) and it worked like a charm. I just dissolved a small amount in water, put in a spray bottle, and sprayed down the soil. I think it only took about three applications to eliminate them (I don't recall what the waiting period is to break the egg cycle).

[Derkshaman]

Exactly what I was looking for Kykeion, thank you. Harmless for cacti seedlings?

Edit: Hey, looks like it's another formulation of BT!

Mr.

☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ

So you collect ants and leave them to unleash hell upon the fungus gnats? Do they dig down and eat the larvae?

Anyways, applying the BT and putting thicker layers of sand... fingers crossed this is enough to solve the problem...and that the seedlings don't die from their injuries.

Edited December 5, 2015 by Derkshaman

[Cubism]

There's also an oz company selling predatory nematodes if your interested. No too expensive either. Can't remember the company name but if you Google the product name "gnatnem" you'll find it.

[Kykeion]

Should be, it didnt bother mine.

[theuserformallyknownasd00d]

Bugsforbugs might be able to help if that's not what cubism is talking about

[☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ]

Derkshaman yes they do

I'm still trying to ID these , at first i thought pharoah ants or Argentine ants, but they could perhaps actually be thief ants ...

but then again , ... they could also be one of the pheidole species , hopefully the ones from florida or texas with any luck

... but yeah it's opened up a whole new branch of biology hobby :3

these are purely tropical .. they don't like to leave the humidity and warmth of my rainforest box unless its the very height of summer and they always return home without going very far... (maybe 2 metres or so)

very cool to watch , and to watch them slay sciariad who dare enter (and the odd biscuit piece... and drip of honey to try deter them from nurturing scale insects)

-just tried borrowing a few to introduce them to the glass terrarium I just germinated caapis in ..

Edited December 5, 2015 by ☽Ţ ҉ĥϋηϠ₡яღ☯ॐ€ðяئॐ♡Pϟiℓℴϟℴ

[Spanishfly]

Fungus gnats are attracted to peat - avoid this if they are a problem to you. I have only ever had a problem with them when I have grown indoors - I don´t any more - but their horrid grubs have eaten right through the base of a cactus before now.

[Derkshaman]

Derkshaman yes they do

I'm still trying to ID these , at first i thought pharoah ants or Argentine ants, but they could perhaps actually be thief ants ...

but then again , ... they could also be one of the pheidole species , hopefully the ones from florida or texas with any luck

... but yeah it's opened up a whole new branch of biology hobby :3

these are purely tropical .. they don't like to leave the humidity and warmth of my rainforest box unless its the very height of summer and they always return home without going very far... (maybe 2 metres or so)

very cool to watch , and to watch them slay sciariad who dare enter (and the odd biscuit piece... and drip of honey to try deter them from nurturing scale insects)

-just tried borrowing a few to introduce them to the glass terrarium I just germinated caapis in ..

This is very cool. Way to have some fun while also solving the fungus gnat issue. Was not expecting such creative solutions... biological ones too, even better.

Seems like it might be suitable for me- usually a pretty cold house and just started using some sort of heated & humidified chamber for seedlings... I'll get some ants thriving in there and have my own little fungus gnat-less ecosystem.

But, I assume B. Thuringiensis would also kill the ants so it might be one technique or annother.

Also, thanks for the suggestions on predatory nematodes! That is too cool. Has anyone used them with success before? Are they difficult to cultivate in typical soil?

As SpanishFly pointed out... yes they happen to be the containers where much peat was used, I'll avoid it in the future!