Orchid wilt is a fungal disease

OrchidsWilt (Orchid Fusarium wilt) [also known as Paphiopedilum wilt] Distribution: Nearly worldwide. Pathogen: Fusarium oxysporum, Fusarium oxysporum f. cattleyae. Hosts: Cattleya, Cymbidium, Dendrobium, Paphiopedilum, Phalaenopsis, Vanilla, etc. Symptoms: It mainly infects the rhizome, turning it purple, with the vascular tissue becoming pinkish-purple, and it can also spread to the pseudobulbs and roots. Because the vessels become blocked, the leaves turn gray and the plant withers and dies. Phalaenopsis affected by this disease is often accompanied by root and stem rot Control: Remove diseased plants and infected soil, and spray, soak, or drench the soil with a 500-fold dilution of 50% captan or 50% carbendazim wettable powder. A 0.5% formalin solution may also be used. (Chen Xinqi, Ji Zhanhe)