How to prevent and treat leaf spot disease in clivia? Detailed methods

Symptoms: It damages the leaves. Initially, light reddish-brown oval elongated spots appear, the surrounding tissue turns yellow, and the boundary between diseased and healthy tissue is distinct. Later, they expand into irregular large patches, and small dark brown granules, which are the pathogen's pycnidia, are produced on the diseased areas.

Disease characteristics: This disease is caused by a fungus. The pathogen is Coleophoma narcissi. The fungus overwinters on diseased plants or enters the soil with diseased fallen leaves, and in spring or autumn of the second year produces conidia that spread by wind and rain, and in greenhouses it can spread at any time. After the spores land on the leaves, the spores germinate and invade, and after a few days of incubation the disease appears. In warm and rainy seasons, conidia are produced again for secondary infection. High temperature and high humidity, shaded conditions, or overly wet potting soil make the disease likely to occur, and excessive or one-sided application of nitrogen fertilizer makes the disease severe.

Prevention and treatment methods:

(1) Horticultural control: promptly prune diseased leaves when found; appropriately increase potassium fertilizer; avoid excessive watering and prevent moisture from lingering.

(2) Chemical control: spray at the early stage of the disease. The following fungicides can be selected: 50% benomyl wettable powder at 1000 times dilution, 25% carbendazim (bromothalonil) wettable powder at 500 times dilution, 15% imibenconazole wettable powder at 3000 times dilution, 40% Fuxing (flusilazole) emulsifiable concentrate at 7000-8000 times dilution.