It would seem that this year has been exceptionally bad for gnat infestation. We have had a lot of customers being overwhelmed by attacks from the little critters.
Our usual remedy would have been GNAT OFF but as this has been removed from the shelves by the manufacturer we've been left searching for a solution.
As always at The Hydro Store we tackle problems head on and we set about researching and testing to see what we could do to get to grips with the problem that was seriously damaging plants and crops. I think its fair to say that gnats are probably the hardest pest we've ever tried to beat if you have an infestation you are going to have to be very proactive to beat them.
Why is that the case? Well, the little black flies you see buzzing around the room love to lay eggs in wet conditions so your coco/soil of your pots or rockwool is ideal. These eggs then hatch into lava that live in the growing medium feeding on the roots of your plant so slow growth and yellowing of leaves results, some times even killing the plant. These lava then come to the surface turn into adult flies and the cycle goes round and round getting worse and worse.
So what should you do?
First off, you need to break the cycle of adults laying eggs in the growing medium by putting a top dressing on your soil/coco/rockwool. We recommend using Gnat Nix from Growstones. See our video below. Apparently you could also use sand, which kind of makes sense, but we haven't tested this.
Next, we need to think about killing the lava that are probably already in the soil. The only product that we could find available to the Hydro industry was Tanlin from Canadian Xpress. Its a highly concentrated liquid that goes in with your feed as a rootzone drench to kill the lava. We tested Tanlin and it works well but we'd recommend using it at its strongest dose in plain water, then giving your plants a good soak and ditching any runoff that comes out the bottom of your pot.
Finally we need to kill the adults, the flies. For this you can use sticky fly traps and a foliar spray. We'd recommend both to beat these buggers as you've got to really declare war on them. Get the fly traps hung up in the air. We like the fly traps that have square markings on as it allows you to see easily how bad your infestation is - as you get less flies in each square you know you're winning. Another very effective method is to cut the traps into 2cm strips and lay them on the top of your pot, this really catches a lot of the adults coming into lay eggs.
As a foliar spray we recommend SB Plant Invigorator as it can be used in Veg and Flower so go ahead and give your plants a good spray with this when your lights are off. The gnats are less active when the lights are off so you can catch them unaware.
Hope you find this helpful and good luck. If you like to chat to us more about pest problems or anything at all don't hesitate to call our team, we are here to help.