A  Phytophthora cactorum and possibly other forms of the fungus are a constant problem where orchids are grown outdoors in shadecloth structures or hung under trees. In my experience, the fungus causes most problems in spring and autumn, at the change of seasons. When plants are placed too close to soil, water splash will easily introduce fungal spores to the growing medium, as the fungus is found in most temperate areas of the world. Benches need to be at least a yard above soil level outdoors; a weed mat or a layer of gravel on the ground will also help prevent infection. In spring, the developing growths rot out and sometimes, with increasing temperatures and lowering humidity, the infection will not proceed. But in autumn, the conditions increasingly favor the fungus and plants will quickly be come infected beyond saving. At the first sign of problems, space the plants, dry them out and remove any damaged growths or pseudobulbs. Spray or drench with an appropriate fungicide; the label will con firm effectiveness against Phytophthora, and be very vigilant to ensure that a small pocket of infection doesn’t proceed to an epidemic. - Andy Easton