Occurrence Patterns and Control Methods of Lotus Root Brown Spot Disease
Brown spot disease is a major disease of lotus root, widely distributed, and can occur in spring, summer, and autumn. Generally, diseased plants account for 30%-50%, and in severe cases, the incidence rate can reach over 80%, significantly affecting lotus root yield and quality. 1. Symptoms This disease mainly affects the leaves and leaf stalks of lotus root. In the early stage of leaf infection, small brownish-green...
Brown spot disease is a major disease of lotus root, widely distributed, and can occur in spring, summer, and autumn. Generally, diseased plants account for 30%-50%, and in severe cases, the incidence rate can reach over 80%, significantly affecting lotus root yield and quality.
1. Symptoms This disease mainly affects the leaves and leaf stalks of lotus root. In the early stage of leaf infection, small brownish-green spots appear, which later expand into reddish-brown to dark brown irregular to polygonal necrotic lesions, often surrounded by a yellow halo, measuring 2-10 mm. The lesions often have concentric rings, and in the later stage, the lesions frequently merge into large patches, turning brown and drying up. If the leaf stalk is infected, it easily breaks and droops. When air humidity is high, a sparse grayish-brown mold layer forms on the surface of the lesions.
2. Occurrence Patterns The pathogen overwinters with diseased plant residues. When temperature and humidity conditions are suitable, conidia are produced, forming primary infection. After the disease develops, conidia are produced for secondary infection.
3. Control Methods ① Agricultural control: Combined with cutting stubble before winter, thoroughly clean up diseased and old leaves, concentrate them for crushing and composting to reduce field inoculum sources; strengthen fertilizer and water management. In areas where the disease frequently occurs, increase the application of phosphorus, potassium, and zinc fertilizers, drain and sun-dry the field at appropriate times and to appropriate degrees, promote root growth, and enhance plant disease resistance. ② Chemical control: In the early stage of the disease, you can use 50% Anilazine wettable powder at 500 times dilution or 40% Fuxing emulsifiable concentrate at 5000 times dilution, or you can use 70% Thiophanate-methyl wettable powder at 600 times dilution or 40% Iprobenfos wettable powder at 600 times dilution for spraying, once every 7-15 days, for 2-4 consecutive sprays.