Hydrogen peroxide-H2O2

[Ravi]

HP is an unstable liquid it dissociates in to nascent oxygen and free radicals which are responsible in damaging the DNA of a microorganism, in the context of Orchids this makes sense in sanitising root system after they are rid off dead mushy damaged roots.
In clinical practice H2O2 is one of the best time honoured agents in cleansing infected wounds especially gangrenous wounds which are needed to be irrigated thoroughly freeing the wound from sloughing, this exercise is similar to sanitising the dead roots of Orchids.