by "still" I meant "slow moving air" or "no moving air"..
perhaps its always breezy for your plants? could be..so the stillness might not be the problem..
Mold generally likes four things: "cool, damp, dim, and still,"..but it doesnt need to have all four..
perhaps just two of things have been more common lately that usual?
less sun? (cloudy)..rainy and cloudy? (dim and wet) cooler than usual? even for just a day or two?
Its hard to know exactly what triggers it..but once conditions change, (either naturally, or you make them change)
the mold will go away..
Physical removal is best... this stuff will grow out in full blazing sun and with excellent ventilation in my greenhouses. Summer in Georgia definitely does not kill it. Perhaps the spores germinate during the cool, wet weather, but as long as it's there you won't be able to eliminate it by changing conditions. Other fungi are easily killed by light or air circulation, but this stuff is a completely different ballgame.