Pest control and top dressing

[CannadaJ]

I've had a bit of a fungus gnat issue from some new soil. I keep reading how important it is to keep the top of soil dry. I'm typically an under watering kind of guy.

I didn't have an issue until I top dressed, and had to keep the top soil wet to break down the amendments (Gaia Green). I'm currently using Neem Oil, diatomaceous earth, sticky traps and beneficial nematodes to control the outbreak.

How can I keep the soil dry if I'm top dressing and need to keep the top of soil wet? My engineering mind might be getting in the way of the answer, but these two things cannot exist together. Yet I keep hearing them together. In the name of sanity and obliterating bro science (it has its place, I acknowledge), what is the answer? ; )

How are people dealing with fungus gnats and top dressing? Is there a rational answer or just pure luck and circumstance?

Julien

 

[Growtogrow]

I usually make a tea and lightly top dress do not over water over watering will definitely cause you to have fungus gants for real they will live in your top soil and they'll live on your plants. Let your pots dry out more. And use the tea more often. That's a simple answer and that's how I usually do it.

Happy growing

 

[CannadaJ]

Thanks Growtogrow - how long are you keeping your top of soil wet to break down top dressed amendments?

 

[JP1]

Get some mosquito bits and just sprinkle some on top of your soil. Gnats will be gone in 2 weeks. Really monthly. Put the glue traps directly on top of the soil and you can speed it up a little Mosquito bits will get the larvae and the traps will catch the adults

 

[KIS]

SF Nematodes. There are even timed release ones now available from Biobee. Bti works too like others mentioned. https://www.kisorganics.com/blogs/news/97755777-fungus-gnat-treatment?_pos=1&_sid=712995289&_ss=r

 

[CannadaJ]

The nematodes are having quite the success.

Still curious about keeping soil both wet and dry at the same time. Is it even possible? Or does it mean that when you top dress with organics, you can't keep your top of soil dry.

 

[KIS]

I think just make sure you are not overwatering and you'll be fine.

 

[CannadaJ]

I think just make sure you are not overwatering and you'll be fine.

Thanks. I'm also considering a straw mulch and cover crop to keep the top moist. Is this contributing to fungus gnats?

I do have a healthy population of nematodes and they seem to have completely destroyed the gnat population. I haven't seen one in 3 days. I'll keep up with nematodes and neem oil (during veg only, soil drench early flower, etc.).

J

 

[Dankerson]

I wouldn't worry too much about it. Sounds like you are already doing the major pest control items for fungus gnats. Once I started growing organic and doing top dresses I ran into the same issues. I always have one or two flying around my tent or lung room despite my pest control efforts. It's been like that for me most of this grow since I started it, it hasn't gotten worse but I've never been able to completely erradicate them so I just keep a close eye on it to make sure it doesn't get worse and just leave it as is.

As far as watering I lift the pots for weight, it's very easy to tell a full pot from a dry one. It's a quick way to tell if it's dry or not. The only way I really got watering down was when I started doing that. Letting the entire pot dry out enough is a good way to control fungus gnats. If you really wanna axe them look into bottom watering.

 

[CannadaJ]

Dankerson,

Thanks good to know they are part of most organic grows, which is what I suspected. The key seems to be to control them to prevent full blown infestations.

I tend to lean on the underwatering side. But when I top dress at week 3 or 4, I want to keep the top moist to allow my organisms to break down the dry amendments. I think adding nematodes right before the top dress will help with the next grow.