Orchid anthracnose is a disease caused by fungi

OrchidAnthracnose (Orchid anthracnose) [also known asOrchidspot disease (Orchid spot)] Distribution range: worldwide; relatively common throughout southern China. Pathogens: Collectotrichum gloeosporioides, Collectotrichum cinctum. Hosts: Aerides, Cattleya, Coelogyne, Cymbidium, Cypripedium, Dendrobium, Eria, Laelia, Oncidium, Paphiopedilum, Phaius, Phalaenopsis, Pholidota, Vanda, Vanilla and other genera. Symptoms: water-soaked black or brown raised small pustules appear on pedicels, buds and the lower surface of tepals and petals, or occasionally on the upper surface. On the leaf surface, several dark brown or pale gray areas appear, containing many black spots that gather into bands; the bands run transversely or form concentric rings. The lesions clearly show as strips of black tissue, and are often surrounded by yellow bands. As the black lesions develop, the surrounding tissue turns yellow or grayish green, and becomes sunken. The spots are round or oval, initially reddish brown, later turning dark brown or gray. On the spots of dried old leaves, small clusters of spores or occasionally fruiting bodies can be seen.Orchidaffected plants arch and become weak or die. Control: cut off the infected organs, and spray with 50% carbendazim 800-fold solution or 75% thiophanate-methyl 1000-fold solution. For pre-disease control, spraying with 65% zineb 600-800-fold solution or 75% chlorothalonil 800-fold solution gives good results. Note: excessive nitrogen fertilizer easily leads to infection by this pathogen. Anthracnose easily infects Chinese orchid types, such asCymbidium goeringii、Cymbidium kanranetc., mainly during the plum rain season. The pathogens of vanilla anthracnose also include Glomerella vanillae and Calospora vanilllae, but the symptoms are similar, and the control methods are also similar. (Chen Xinqi, Ji Zhanhe)