Fungus Management in Tropical Orchid Growing

Battling Fungus in Tropical Orchid Cultivation

Kristin lives in the tropics, grows orchids outside year-round. Battling fungus despite preventative and systemic fungicides. Asks: must all affected leaves be removed? After treatment, is fungus dead on those leaves? Can it still spread? She removes leaves gradually but unsure of importance with systemic fungicide.

Expert Response

Kristin, fungus spreads via airborne spores that land on plants, germinate when moist. Fungal hyphae may die after treatment, but spores resist fungicides. I use combined approach: remove any tissue showing fungal damage (spores may remain). Spray with copper-based fungicide (e.g., Kocide) to coat leaves and kill germinating spores. Repeated applications needed. Systemics have limited lifetime and only protect actively growing tissues that take them up. Focus on producing new disease-free tissues. In humid tropics, increase air circulation to promote evaporation, keeping surfaces drier.