How to control leaf blight of potted white orchids?

Branch blight is easy to occur when the indoor ventilation is poor, the light is insufficient, the basin soil is too wet and the alkali is too easy.

Prevention and treatment methods: ① set a better light position, open windows at noon during the day, keep the basin soil dry, and apply alum fertilizer water and 3% ferrous sulfate solution every 20 to 25 days, which can prevent the disease. At the beginning of ②, if there are not many leaves, you can smear medical Dakening on the lesion or spray 2% ferrous sulfate solution every 4 days for 3 times in a row.