1. Seeding diseased seeds, which will cause disease after emergence and produce conidia, which spreads in the nursery bed. 2. The overwintering bacteria source on the diseased body, in suitable conditions, produce conidia spread by wind and rain, infecting celery, and then producing conidia repeated infection. 3, germs grow well in cold and humid conditions, the optimum temperature for the disease is 18-25 °C, humidity above 95%, greenhouse celery is generally more severe. In case of continuous rainy weather, frequent temperature fluctuations, or dew condensation, and plant growth will weaken, the favorable diseases will rapidly expand and spread. The disease can continue to develop during the Tibetan period and the loss is often heavier than in the field. JIANGSU CLS TECHNOLOGY CORP.LTD , https://www.js-cls.com