Orchid rust: Sphenosporakevorkianii

Sex spore (O) and rust spore (I) unknown, pydiospores (11) small, raised under epidermis, cinnamon brown, epidermis dehiscence releasing yellow-brown to yellow-brown spores The teliospores (dishes) are borne beneath the epidermis of the lower leaves in concentric, cushion-shaped, waxy yellow-brown colonies.

(1) Hazard: The disease was discovered and described by Cummins in Venezuela in 1945 on Cycnoches ventricosum var. chlorochiron P. H.Allen. Other hosts are Bletia sp, Catasetum sp, Epidendrum nocturnum and Mormodes s P. The number of host species affected by the disease is small and not serious.

(2) Symptoms: On Cycnoches vesticosum var.chlorochion and Epidendrum nocturnum, pin-sized cinnamon spots were formed under the leaf epidermis at first, and then the spots aged and broke through the leaf epidermis to produce cinnamon brown to golden brown powdery spores.

(3) Control method: Remove all diseased plants that are not burned, spray the susceptible plants with thiram at a concentration of 800 times, and apply once every 30 days. (Liu Zhongjian)