symptom
After the celery seedlings are infected with the disease, they show slow growth. When the temperature reaches above 20°C, the leaf color changes from green to yellow-green, causing the seedlings to wilt or die. Adult plants are infected, the leaves are dull and the leaf color becomes dull in the high temperature season, and in severe cases, the leaves are chlorotic or the mesophyll between the veins appears yellow and green mottled, the vascular bundles of the diseased stems are turned brown or the roots, root necks, and petioles turn red , the root system rots and the whole plant dies.
pathogen
Verticillium albo-atrum Reinke et Berthier, known as Verticillium black and white Verticillium, belongs to the fungal kingdom Ascomycota anamorphic Verticillium.
Transmission routes and disease conditions
The fungus stays in the soil for overwintering mainly as mycelium. When the conditions are suitable in the next year, the pathogen invades from the young fine roots of celery, causing the host cortex to rupture or rot. Upward transport of moisture is hampered. The incubation period of the disease is about 20 days. High soil temperature or 20-32°C is conducive to the disease, and the temperature is 28°C and the disease is severe. Less than 7.7 ℃ or higher than 36 ℃ mild onset. Dry plots or seedling beds are prone to disease in production.
Prevention method
①Choose varieties resistant to Verticillium wilt.
②Spray or pour 1500 times liquid of 70% hymexazol wettable powder or 700 times liquid of 30% hymexazol water agent, 500-1000 times liquid of 1% phenazine-1-carboxylic acid suspension concentrate.
