Leaf Rot in Orchids
- Leaf rot is fairly common in orchids. In its early stages, the disease is identifiable by leaf yellowing or mottled discoloration. Over time, spots darken and multiply, leaf tissue becomes soft and leaves may be easily pulled from the plant. Leaf rot may not kill the plant directly, but it can weaken it, making it susceptible to attack from insects or other diseases.
- Crown rot is similar in appearance to leaf rot, but it affects the uppermost leaves, known as the "crown" of the orchid. Crown rot can rapidly infect the entire upper part of the plant. Brown or black rot appears as small brown or black depressions on leaves, which can be caused by bacteria or fungus. The spots become larger as the disease travels throughout the plant and can eventually cause plant death if left untreated.
- If the infection is localized, cutting off the infected leaves is the first step in the treatment of leaf rot. Use very sharp, sterilized scissors to remove affected leaves. Isolate the plant and apply a bactericide or fungicide specially formulated for orchids. Some gardeners prefer a more organic remedy: cinnamon. A liberal dusting of the spice is effective in killing some types of bacteria. If treatment is successful, spots on the leaf should dry up within 10 days. Because different orchid species are susceptible to specific diseases, consult a professional orchid grower or plant supply staff for detailed information.
- Sterilize garden tools after use to avoid spreading infection. Avoid wetting the leaves when watering the plant. Isolate plants under treatment; some diseases travel via splashing water from infected plants. Fungus and bacteria favor warm, moist conditions. Increase air flow and avoid overcrowding orchids.
