What are the white spots on the leaf

look up cornell forumula or buy some greencure -- both similar ingredients. dr. zymes? copper soap spray... horticultural oils like neem have some antifungal properties, hydrogen peroxid... spray both sides of leaves. Could take some h2o2 and gently wipe leave off, make sure it gets wet over entire surface. any homemade stuff should have a surfactant to diminish surface tension of water... it helps it spread out on leaf. if you can isolate a plant or two fromt he rest, that would be best, as it can spread. some plants will be more resilient than others, but none are immune. i've had some problems with mold lately.. each time with the same strains as the starting point.