I have seen small amounts of hydrogen peroxide mixed in with potato dextrose agar when working under less than ideal conditions for mycology use. The theory was that living organisms (the mycelium in this case) could process the peroxide in small concentrations, while spores would be destroyed, and in practice, this led to a tremendous decrease in contamination when working without a glove box or flowhood. Does anyone have experience trying this with malt agar in their plates or slants?