How Much Captan to Use on Orchids?

Spray Solution

• In "All About Orchids," Charles Marden Fitch notes that orchids benefit from a solution of 3 1/3 tbsp. of Captan per gallon of water as a drench for rust fungus. "Orchids of Asia" by Eng-Soon Teoh suggests this solution for Cercospora leaf spot, while the "Handbook on Orchid Pests and Diseases" by Harry Burnett recommends only 1/2 tsp. of Captan to prevent crown rot while watering new divisions.

Paste

• For orchid leaf or root wounds that need to be safeguarded against rot or other fungal infection, a paste made of Captan powder wetted only enough to make a thick paste is the easiest way to apply the fungicide. In this case, the necessary amount of Captain is enough to cover the wound.

Dust

• Dusting the entire orchid root area with Captan helps prevent root rot when the orchid is planted in a medium that may hold too much moisture, or when it may receive water too frequently, according to the "Orchid" magazine article entitled "Growing Orchids in Mud."

Warnings

• "Orchids of Asia" warns that Captan should not be used to treat Curvularia flower blight, since Captan injures orchid flowers. When using Captan as a spray, powder or paste, it is important to avoid contact with any flowers or buds on the orchid to prevent injury.