Q.I Think I May Have Killed My Plants-i Used 1 Cup 3% Hydrogen Peroxide To 3 Cups Water? Please Help
I have a nasty gnat problem, I’ve used a bunch of homemade remedies and none worked. I read about hydrogen peroxide dilute and putting sand on top. I may have messed up the ratio, I’m really upset one of these plants is 25 years old! Did I kill my plants? Is there anything I can do?
Certified GKH Gardening Expert
The peroxide may have killed off the fungus gnats, which were eating any rotting roots or infections in the soil. This can allow the underlying infection to take over.
If you ever notice an abundance of fungus gnats it will mean that there is a fungus in the soil. If they fly out of the soil (which they don't like to be outside of) it will indicate that the soil is far too wet and suffocating them. Once the infection is gone, there will be no more food for the fungus gnats and they will leave the plant.
Peroxide will kill off bacterial pathogens, but will not do much in the way of fungal infections. In fact, for severe fungal infections, peroxide may take away beneficial bacteria. This is competition for the fungus, so removing them will allow fungal infections to take over.
From here, you will need a strong fungicide. Copper based is best. Test the pH of the soil, since compounding treatments on top of each other will cause a very inhospitable environment for plant. Once you get the pH back in order, and treat with a strong fungicide, you will notice signs of recovery.
Here are some articles that will help: