I looked into it once, and this is what I learned - and please anyone correct me if I'm wrong:
- H2O2 works nicely for sterilization of seeds, washing them in a diluted solution for a few minutes, then rinsing (there's claims that leaving a very light dilution of H2O2 in the solution for germination of very slow seeds can be an extra measure for preventing molds, but I've seen seeds deadly pale after spending weeks in a tissue with 0,5% H2O2 dilution and I'd personally use other tips for sterility).
- H2O2 can be used to help clean dubious water before irrigation, adding a 1% regular peroxide to it (for the standard pharmaceutical H2O2 with a 3% concentration, meaning 10 ml per liter of water). However, it's convenient to leave the water resting for a good while before using, particularly in the sun since heat speeds up degradation of H2O2. And why is preferable to degrade H2O2 once it has reacted with pathogens in water, before using it? Because...
- H2O2 will not only help decompose dead organic matter, or kill lots of fungi and some pests (which it does) but will also kill beneficial organisms, easily sweeping away micorrhizae, trichoderma and other good guys in your soil. So I don't think that watering healthy plants with 1% H2O2 is a very good idea if you are growing in organic substrate, and most specially if you're adding organic nutes and beneficial organisms to your soil.
- The exception to this may be inorganic substrates, and particularly hydroponics. As the article you posted says, H2O2 can help to keep good oxygen levels in the hydroponic solution, and perhaps prevent molds and fungi when growing in inorganic substrate.
- H2O2 can also be applied diluted (again, 1-2% max for 3% H2O2) to soil that needs to be recycled and sterilized, precisely due to its biocidal properties.
- And of course, it can be very valuable for treating root rot and molds as the article says. But keep in mind what happens with people and antibiotics... if you take antibiotics, ALL of your intestinal flora will be decimated. That's why supplementing with probiotics is a great idea to recover your guts. And same applies to plants and roots, if you apply H2O2 to treat root rot, your plants might appreciate it a lot if you help them restore their soil symbionts afterwards.
- And another thing... if you water with H2O2, avoid fertilizing in the next watering. The roots will be particularly sensitive and nutrient absorption will go faster, so the regular dose of nutes might unexpectedly damage your plant. So after H2O2 treatment, clean water... and after that you can resume with nutes if necessary.
Hope it's useful.
Mandrake