To use hydrogen peroxide as a foliar spray, mix 1 part hydrogen peroxide with 2 parts water in a spray bottle. Spray the mixture onto the leaves of the plant. Avoid getting any on the stems or plant's roots, as it can cause damage.
Hydrogen peroxide kills root rot-causing bacteria and fungi and restores the oxygen balance in the soil which boosts your plants' growth and health. Due to its chemical similarity to water, hydrogen peroxide is one of the safest chemicals you can use in the garden to combat root rot.
Cut off any diseased roots using a sterile cutting tool like a knife or scissors. You want to make sure that you're cutting off the roots that are black and mushy. After you've cut off any dead roots, we recommend soaking them in an 80:20 solution of water to hydrogen peroxide. Five minutes or so should be sufficient.
Apart from being more mindful of how often and how much water you give your plants and plant roots, you can also use a mixture of 3 percent hydrogen peroxide concentration mixed in 1 quart of water once a week to encourage healthy root growth in your plants' roots or treat the spread of root rot and root decay.
Under aerobic soil metabolism conditions, hydrogen peroxide degrades with a half-life of ca. 1.4 hours in diluted test solutions. This half-life value was extrapolated to ca. 7 hours for concentrated test solutions.
It is perfectly safe for plants when properly diluted and used in moderation. Adding hydrogen peroxide to water promotes better growth in plants and boosts roots ability to absorb nutrients from the soil. Diluted 3% peroxide adds needed aeration to the soil of plants and helps control fungus in the soil.
If you use a higher concentration of hydrogen peroxide on the foliage of the plant you run the risk of burning it. You could burn the roots, but since it's necessary to kill the root rot-causing bacteria, it's a risk worth taking.
First option: Remove the plant from its pot.
Gently remove all the potting medium from around the roots of your plant. Once completely exposed, either spray or pour the hydrogen peroxide solution all over the root ball. Repot the plant in a new, damp potting mixture. Let the soil dry before watering the plant again.
If you are treating a sick plant or one infested with insects, use a slightly stronger mixture of one tablespoon of hydrogen peroxide in eight ounces of water. Don't use hydrogen peroxide on your plants more frequently than twice each week. If you make more than you need, you can store it.
It is not possible to reverse root rot. The treatment of this disease involves removing the affected portions of the plant. Once the rotting or dying parts have been removed, they can then be repotted in fresh soil to give the remaining healthy roots a fresh start.
Use the most effective fungicides (those with thiophanate-methyl, polyoxin-D, triflumizole or fludioxonil) preventively.
Baking Soda Fungicide
Common household baking soda is a natural product used for combating plant fungus problems. Mix 1 tbsp. of baking soda with 2-1/2 tbsp. of vegetable oil in 1 gallon of tap water.
For planted seedlings: Spray with H2O2 solution of 1 part H2O2 3% to 32 parts water (eg: around 30mls per 1 litre - measuring cup recommended). For established plants: Mix 1:1 ratio of 3% H2O2 and water (eg: 1 cup of each). Bottom or top water as usual (water soil only, do not pour on leaves).
Hydrogen peroxide, well known as an ingredient in disinfectant products, is now also approved for controlling microbial pests on crops growing indoors and outdoors, and on certain crops after harvest. This active ingredient prevents and controls bacteria and fungi that cause serious plant diseases.
The breakdown of hydrogen peroxide into water and oxygen is catalysed by catalase enzymes in plants and animals. Hydrogen peroxide naturally breaks down to water and oxygen, but very slowly. The catalase enzyme in yeast and other materials, such as potato and liver, speeds up the reaction greatly.
Hydrogen peroxide does not contain plant auxins, but it is the one DIY rooting hormone that you can try to use when propagating.
When peroxide is mixed with soil it will react with living microbes as well as dead organic matter. In fact, an older method for measuring the amount of organic matter in soil used peroxide as the main reagent. During this reaction oxygen is produced and can be observed as bubbles.
Hydrogen Peroxide Inhibits Bacterial Growth
While hydrogen peroxide isn't always effective as antibacterial agent, it is a bacteriostatic agent, meaning it inhibits reproduction of bacteria. In so doing, it can help to avert worsening of infections without actually killing all of the bacteria.