Renfro
Well-Known Member
Agreed, PM love RH% fluctuation. The dry time allows the spores to propagate easily and the wet times cause it to spawn and grow in a matter of hours. So keep those numbers nailed down indeed.The operative word here is 'stay'. Having RH go up and down a lot is ideal for the spread of powdery mildew.
@Renfro you know this, I'm just driving the point home for those who may not.
It is important for growers to remember how humidity works. The cooler air is the less water it takes to put it at 100% saturated. So having warm air thats at 50% cool down will cause the humidity to rise. That is why many growers experience their first bout of PM after a period of lights out where temps dropped and ventilation / dehumidification is inadequate. To make it a double whammy, dehumidifiers are less efficient in cooler air.