Orchid flower blight is a fungal disease

① Fusarium flower blight Distribution: worldwide. Pathogen: Fusarium moniliforme Hosts: Arachnis, Dendrobium Symptoms: The entire flower or inflorescence, especially the buds, is susceptible to infection. Infected parts show sunken dark brown to black lesions, usually covered with a white powder (mycelium) and small pink spores. Severe infection can cause flowers to turn yellow and drop at the bud stage. Control: Cut off diseased flowers. Spray with 80% zineb or 80% maneb wettable powder at 400-600 times dilution every 4-7 days. A 50% carbendazim wettable powder at 500 times dilution can also be used for spraying and drenching the soil. Note: It can also infect leaves, known as Fusarium leaf spot, presenting as small spots, mostly on injured tissue. ② Botrytis blossom blight Distribution: worldwide; more common in the United States. Pathogen: Botrytis cinerea and other species of the genus. Hosts: Cattleya, Cymbidium, Dendrobium, Paphiopedilum, Phalaenopsis, Spathoglottis, Vanilla, etc. Symptoms: Pale brown, very small water-soaked spots appear on the tepals. These spots enlarge and cause the entire flower to rot. The deformed pod disease of vanilla is also caused by this pathogen. Control: Infection rates are high in humid environments, so humidity should be appropriately reduced, especially at night. First cut off diseased flowers, then spray with 80% zineb-maneb wettable powder at 400-600 times dilution or 50% carbendazim at 500-800 times dilution once every 10-15 days, which gives good results. However, captan must not be used, to avoid damaging the flowers. Note: This disease is very common. Infection of differentorchidsgives rise to different names, such as Dendrobium blossom blight, Flower brown rot, Flower brown speck, Flower spot, Flower spotting, Petal blight, Petal speck, Gray mold, etc. ③ Curvularia flower blight Distribution: worldwide. Pathogen: Curvularia geniculata. Hosts: variousorchidcut-flower hybrids. Symptoms: On sepals, petals (one or both sides) or pedicels, oval or round lesions about 0.5 mm wide appear, slightly sunken, pale brown to dark brown. Control: Same as the control methods for anthracnose. Note: It can also infect damaged leaf tissue, such as the leaves of many hybrids of Dendrobium nobile. Chen Xinqi, Ji Zhanhe