Guide to Fungal Diseases in Orchids
Fungal infections infect all living creatures, orchids and plants included. Fungi require damp, dark conditions (usually with poor air movement) to thrive.
Unfortunately ,as every state and country registers the use of different fungicides, it is impossible (and sometimes even illegal!) to suggest the use of particular treatments. Some commonly used fungicides can be banned in one state but not another!
Understanding how fungi reproduce themselves is usually a good start in controlling them. Fungal spores require a spot or pool of water to germinate. Any condition that allows liquid to remain on the orchid for any length of time is inviting a fungal infection. Once germinated, the fungal root system (Mycelium) will invade any damaged tissue and can even penetrate through the stomata (the 'pores') of the leaf tissue. Once inside the orchid itself it is very difficult to cure.
Most fungicides rely on coating the leaf with a metal oxide to kill germinating fungi. It is far easier however to simply water under more suitable conditions and not allow water to sit. Increasing light levels, temperature and air movement are far better solutions when fungal infections are encountered.
The most common fungal infection is Botritis cinerea or Grey Mould. This is the fungi that causes Strawberries to rot and go fuzzy. Just a few hours of water on a phaelenopsis bloom will attract botritis!
Watering on windy, warm sunny days is a fine start. Adding a simple fan, building shadecloth sides or adding more ventilation to your orchid growing area also helps.
One of the most common causes of orchid fungal infections is trying to grow tropical orchids in cooler regions.The orchids stress with the colder conditions and are more prone to infection.