Leaf spot of orchids with orchids

① harm: the known hosts of this pathogen are: Magnolia, Aerides, and Spider Orchid.

(Arachnis), Orchid, Phalaenopsis, Phalaenopsis, Aeridovanda, Ascocenda, Renanthera, etc.

② symptoms: leaf back disease spot is small, the diameter is generally below 1mm, sunken, purple-brown, a number of small disease spots can be combined into larger disease spots, once the initial infection will produce many small disease spots, usually due to intermittent growth of mycelia in the leaves, these disease spots will be arranged into a circle, if not prevention and treatment, the whole leaf back will be covered with small disease spots. Because the pathogen invades the plant from the stomata, the corresponding part of the front of the leaf turns yellowish green and may eventually become purplish brown. When the infection is serious, the leaf will die or fall off.

③ prevention and treatment method: use 50% wettable powder of benzoate 50% to mix 1000 times solution and add small wetting agent, spray 3 times, once every two weeks, and then, if necessary, spray once a month. Fumi Railway can also be used to protect healthy tissue, the concentration is to use 8OO times solution, and expand the adhesive, once every 2 weeks, when the actual situation permits, all diseased leaves should be removed and destroyed. (Liu Zhongjian)