Control methods for lotus root brown spot disease, black spot disease, rot disease, fusarium wilt and viral disease

Field management of lotus root

    I. Lotus root brown spot disease.One of the common diseases of lotus leaves, causing light brown spots on the leaves and local drying. Control: rational close planting to ensure ventilation and light penetration in the lotus field; appropriately increase phosphorus and potassium fertilizer to improve lotus root resistance, and promptly remove diseased and residual plants. At the early stage of the disease, spray with 25% carbendazim 600 times solution or 75% chlorothalonil 1000 times solution.

    II. Lotus root black spot disease.Also known as brown streak disease, it occurs only on the leaves; in severe cases, the spots merge and the leaves turn yellow and withered. Control: thoroughly remove diseased and residual leaves from the field in winter and burn them in a centralized manner. At the early stage of the disease, remove the diseased leaves and spray for control. Use 70% thiophanate-methyl 1000 times solution or 65% zineb 600 times solution or 1:1:160-200 Bordeaux mixture, spraying once every 10-15 days, for a total of 2-3 sprays.

    III. Lotus root rot disease.Also known as fusarium wilt, it infects the underground stem, causing rot; in severe cases, the whole field turns yellow and withered, as if burned by fire. Control: in severely diseased fields, implement a 2-3 year crop rotation. Spray and seal the seed with 70% thiophanate-methyl 1000 times solution or 75% chlorothalonil 800 times solution, cover with agricultural film and seal for 24 hours, then dry and plant. Deeply plow the lotus field and apply 150 kg of lime per mu. When the disease occurs, mix 0.5 kg of 75% chlorothalonil with 30 kg of dry soil, and broadcast it into the shallow-water field.

    IV. Lotus root streak virus disease.Both the affected lotus leaves and underground stems can show symptoms; large polygonal to irregular light brown necrotic spots appear on the leaves, and dark brown anthracnose streak spots appear on the epidermis of the rhizome. Control: select disease-resistant varieties, and promptly control aphids (the virus transmission vector). At the early stage of the disease, spray with 1.5% plant virus inhibitor emulsion 1000 times solution.

    V. Lotus leaf fusarium wilt.The affected lotus leaves turn scorched yellow and withered, affecting lotus root growth and causing reduced yield. Control: keep the lotus field clean and prevent oil pollution from contaminating the lotus field. Sewage and soapy water can also cause lotus leaves to wither. Lotus root is sensitive to herbicides, so herbicides must never be used in lotus fields.

    VI. Common pests and diseases.There are aphids, bagworms, pear green stinging caterpillars and brown stinging caterpillars, which damage the standing leaves and flower buds. Spray with 90% trichlorfon 800-1000 times solution or 40% dimethoate 2000 times solution. Water maggots suck the sap of lotus roots, stems and leaves, causing lotus leaves to turn yellow. Once found, lime can be applied to repel and kill them, at 10-15 kg per mu.