This disease is a common disease of lotus leaf, which produces light brown spots on the leaves, causing local dryness of the diseased leaves. Prevention and control: reasonable close planting to ensure ventilation and light transmission in lotus field; Properly increase the application of phosphorus and potassium fertilizer, improve the plant resistance, and remove the diseased plant residues in time. At the beginning of the disease, spray with 6 times of 25% carbendazim or 1 times of 75% chlorothalonil.

(2) Black spot disease of lotus root

, also known as brown streak disease, only occurs on leaves. In severe cases, the spots converge and the leaves turn yellow. Prevention and control: thoroughly remove the diseased leaves in the field in winter and burn them centrally. The diseased leaves were removed at the early stage of the disease and sprayed with drugs for prevention and treatment. Commonly used 7% thiophanate methyl 1 times solution, or 65% zineb 6 times solution, or 1 ∶ 1 ∶ (16 ~ 2) times Bordeaux solution, spray once every 1 ~ 15 days, and spray * * * 2 ~ 3 times.

(3) Lotus root rot

is also called Fusarium wilt, which infects underground stems and causes rot. In severe cases, the whole field is yellow and looks like a fire. Prevention and control: 2-3 years rotation in seriously ill fields. 7% thiophanate methyl 1 times solution or 75% chlorothalonil 8 times solution is commonly used to spray the seeds, cover the agricultural film and seal them for 24 hours, and then plant them after drying. Deeply turn over the lotus root field and apply 15 kilograms of lime per mu. .5 kg of 75% chlorothalonil and 3 kg of dry soil can be mixed and sprinkled into shallow water fields when the disease occurs.

(4) Lotus leaf and underground rhizome can show symptoms after being damaged by lotus leaf streak virus

, with large polygonal to irregular light brown withered spots on the leaves and dark brown anthrax stripes on the epidermis of the roots. Prevention and control: select disease-resistant varieties, prevent aphids (virus vectors) in time, and spray 1.5% phytosanitary emulsion 1 times at the beginning of the disease.

(5) Fusarium wilt of lotus leaves

The damaged lotus leaves are browned and withered, which affects the growth of lotus roots and reduces production. Prevention and control: keep the lotus field clean and prevent the lotus field from being polluted by oil. Sewage and soapy water can also cause lotus leaves to wither and die. Lotus root is very sensitive to herbicides, and herbicides should never be used in lotus root fields.

(6) Common diseases and insect pests

include aphids, giant salamander, pear-green thorn moth and brown thorn moth, which harm the leaves and buds. It can be sprayed with 8 ~ 1 times of 9% trichlorfon or 2 times of 4% dimethoate. Water maggots suck the juice of lotus roots, stems and leaves, which leads to the yellowing of lotus leaves. Once found, lime can be used to kill them, and the dosage per mu is 1 ~ 15 kg.