Hydrogen peroxide is normally used as a disinfectant to kill microorganisms and thus would likely have an adverse effect on the mycorrhizal propagules; particularly root fragments where the fungal mycellium is exposed through the dry, porous plant tissue. Spores are more resilient – the effects will depend on the concentration of hydrogen perioxide used. We would not recommend using mycorrhizal propagules in water that contains hydrogen peroxide.

If you inoculate your plants and use water without hydrogen peroxide and allow the mycorrhizae to get established, using hydrogen peroxide would not likely have an effect (unless used very frequently and at higher concentrations.)