Control methods of blight spot of Cymbidium

Symptoms: Damage to leaves. Newborn reddish brown oval long spots, yellow surrounding tissues, disease and health border obvious. At the later stage, it expanded into irregular large patches, and the diseased parts produced black-brown small spots, namely conidia of pathogenic bacteria.

Pathogenesis characteristics: This disease is caused by fungi. The pathogen was polyspora narcissus. The pathogen overwinters on the diseased plant or enters the soil with the diseased leaves, produces conidia in spring or autumn of the second year and spreads by wind and rain, and can spread at any time in the shed. After the spores fall on the leaves, the spores germinate and invade, and the disease develops after a few days of incubation. In warm and rainy season, conidia were produced for reinfection. High temperature, high humidity and covering conditions or pot soil too wet easy to disease, partial application, excessive application of nitrogen seriously.

Control methods:

(1) Horticultural control: timely removal of diseased leaves; appropriate application of potassium fertilizer; avoiding excessive watering and preventing moisture retention.

(2) Pesticide control: At the early stage of disease, the pesticide can be selected from 50% benomyl WP 1000 times solution, 25% carbendazim WP 500 times solution, 15% imimazole WP 3000 times solution, 40% flusilazole EC 7000~8000 times solution.