Detailed Explanation of Control Methods for Root Rot in Saposhnikovia divaricata Cultivation
(1) Damage situation and symptoms: Root rot mainly affects the roots of Saposhnikovia divaricata. In the early stage of infection, the fibrous roots become diseased, and the diseased roots turn brown and rot. As the disease progresses, the lesions gradually spread to the stem, the vascular bundles are destroyed, losing their water-transporting function, leading to root-zone rot, and the leaves wilt, turn yellow and die, seriously affecting the yield and quality of Saposhnikovia divaricata.
(2) Pathogen: The pathogen is Fusarium equiseti [Fasarinmequi seti (Corda) Sacc.], belonging to Deuteromycotina, Hyphomycetes, Moniliales, Tuberculariaceae, Fusarium.
(3) Disease occurrence pattern: The pathogen overwinters in the soil and on diseased plant residues in the field, becoming the primary infection source of the disease. Conidia produced in the soil and on diseased plants are spread by wind and rain, causing secondary infection. The disease generally begins in early May, and enters its peak period from June to July. Higher temperatures, greater humidity, and continuous rainy weather favor disease occurrence. Poor plant growth and reduced disease resistance lead to more severe disease; fields with severe damage from underground pests and nematodes also have more severe disease.
(4) Control measures: After harvesting Saposhnikovia divaricata, promptly remove diseased residues from the ground surface and plow the land. When plowing, spread 50-60 kg of lime powder per mu to disinfect the soil. Before transplanting seedlings, soak them in a 1000-fold dilution of 50% thiophanate-methyl for 5-10 minutes, then air-dry before planting. Before sowing seeds, soak them in a 1000-fold dilution of 50% tecloftalam wettable powder, or a 1000-fold dilution of 50% carbendazim wettable powder for 5 hours. In the early stage of disease, pull out diseased plants and spread lime powder in the planting holes for disinfection; alternatively, drench the roots with a 500-fold dilution of 50% carbendazim wettable powder.