it's possible it is not harmful. myco, for example is often put into soil. not all fungi helps or hurts plant. some don't even feed on same things.
could do an h2o2 drench? but in reality you probably will not kill it off... if you start to see it on stems or leaves, throw that plant out. it will only spread.
very low vpd or high humidity are good things to avoid. low RH% isn't all positive either.. that will help promote spread, but does slow reproduction. there is not magical environment that will prevent it... it is omnipresent, too... just requires an opportunity to gain a foothold. unless you are unscupulous and greedy, don't sell wpm-laced weed to ppl, lol. throw it out the moment you realize it is a losing battle. if only 1 plant gets it and it doesn't spread, that's probably a shit plant that is susceptible...
sodium bicarbonate + surfactant -- potassium bicarbonate + surfactant -- h2o2 + surfactant -- horticultural oil, like clarified neem oil can help.
these things are better for prevention and will never completely kill off a serious infection. these change pH and the oil coats the plant material which is an impediment to fungal growth. h2o2 can kill it but would need 10mins or more to do so and light breaks it down very fast... often evaporates long before 10 mins, regardless. During vege and first 1-2 weeks of bloom i apply a neem + castille soap concoctions every 5-7 days. the moment budlets form i stop. i make sure to get one last application in even if a bit earlier than 5-7 days. i've had issues lately.. i think it was more about inbred, weak genetics but all clear this run using the preventative foliage spray.
i wouldnt assume this is a WPM that impacts plants until you see it do so... many fungi come in soils that will do no harm.