symptom
=This crop of spinach infects the roots from the 4th to 6th leaf stage to before harvesting, and the top of the main root and lateral root or the base of the lateral root turns brown to dark brown, and the vascular ducts also turn brown, which is the main feature to identify the disease. The main root and lateral root of the severely affected ones fall off, and the outer leaves turn yellow and wilt first, and then expand inward, causing the whole plant to die.
pathogen
Fusarium oxysporum f.sp.spinaciae (Sherbakoff) Snyder et Hansen, also known as Fusarium oxysporum f.sp.spinaciae (Sherbakoff), belongs to the genus Fusarium of the fungus kingdom Ascomycota.
Transmission routes and disease conditions
Planting a crop of spinach after the harvest of the previous crop, the area of repeated cropping has expanded year by year or the application of immature organic fertilizers has accumulated a large number of pathogenic bacteria in the soil, which provides the conditions for the occurrence of the disease. The pathogen invades the plants when the temperature is 24-28°C, the soil temperature is 10-28°C, and the relative humidity is higher than 90%, causing serious damage. From May to August, the temperature gradually rises and there is a lot of rainfall. The high humidity in the field is beneficial to the propagation and invasion of pathogenic bacteria, and the spinach is under high temperature and high humidity conditions, so the management cannot keep up, and the disease resistance is reduced, which is easy to induce the disease.
Prevention method
①Choose more disease-resistant spinach varieties.
②Crop rotation with melons, solanaceous fruits, and legumes for 2 to 3 years.
③Finely prepare the soil and apply decomposed organic fertilizer.
④ For sowing in June, ridge or row sowing should not be too dense, and ventilation should be paid attention to. Drainage in time after the rain, topdressing in a timely manner, avoid partial application of nitrogen fertilizer, and remove diseased plants in time when found.
⑤ chemical control.
a. Seeds are seed-dressed with 50% carbendazim wettable powder with 0.3% seed weight.
b. Chemical treatment of soil. Before sowing, use 1.5-2kg of 50% carbendazim per 667m2, mix it with fine soil, sprinkle it on the furrow surface and rake it into the soil.
c. Spray 70% hymexazol wettable powder 1500 times liquid or 54.5% hymexazol wettable powder 700 times liquid or 32% azolone·acetoicin EC 350 times liquid at the early stage of the onset, pour 250-300ml per 667m2 .
