For orchid disease control, the fungicide triadimefon can be used

It is a systemic fungicide with strong absorption, mainly used to control powdery mildew and rust, and it has both curative and protective effects. The pure product is colorless crystals, poorly soluble in water, easily soluble in organic solvents, and harmless to bees. Formulations: 5% and 25% wettable powder, 25% emulsifiable concentrate, 0.5% powder, 2% paste. Usage: fororchidrust, it has high efficacy; use 25% wettable powder at 500mg/kg (PPm) spray to control powdery mildew. Liu Zhongjian