Black Spot Disease
Initial symptoms include irregular brown spots on the leaf surface with slight concentric rings. In the later stages, black mold-like substances appear on the spots, often causing several spots to merge, forming large blotches. In severe cases, the entire plant may die. Control measures: Spray 50% carbendazim or 75% chlorothalonil at a concentration of 500-800 times as soon as the disease is detected. [11]
Rot Disease
During the early stages of the disease, blue-black spots appear on the leaf margins, which then spread and become connected, turning the entire leaf brown. Once the lotus root is infected, the central area turns brown and gradually extends to the joints of the root and the stem, leading to longitudinal necrosis. Control methods: At the initial stage of the disease, spray a 500-600 times diluted solution of 50% carbendazim for prevention and control. [11]
False Webworm
Emerging larvae congregate on the leaf undersides, gnawing at the leaf flesh while leaving the epidermis and leaf veins intact, making the affected leaves appear like screen doors, with a grayish-white hue. As the larvae grow slightly larger, they disperse and continue to feed, biting the leaves into notches and even consuming flower buds and flowers. The damage is most severe from June to October each year. Control measures include promptly removing and destroying the infested leaves, and spraying a 1000-fold solution of methamidophos in the evening when the larvae are concentrated and causing damage. [11]
Aphids
Aphids exhibit strong adaptability to climate, with a widespread distribution. They primarily feed on the stems and leaves of plants, particularly the tender parts. Due to their strong reproductive capacity and adaptability, aphid populations can be massive, making it difficult to achieve a complete cure through various methods. Regular application of a 80% DDVP emulsion spray, diluted 500-1000 times, is necessary.