High temperature and high humidity Zizania latifolia is prone to flax leaf spot.

Leaf spot of Zizania caduciflax is a fungal disease. In recent years, with the increasing area of Zizania caduciflora, the scope of the disease has gradually expanded, and the disease is becoming more and more serious. The disease can occur in the whole growing period of Zizania caduciflora. The main harm to the leaves, the early leaves appeared yellow-brown spots, and then expanded into sesame-sized brown spots, a few into strips, the disease spot is often surrounded by a yellow halo, the late spot edge is dark brown, the middle is yellow-brown or gray-white. In severe cases, the disease spots are densely covered, and some of them are connected into irregular spots, and when the humidity is high, the disease spots are dark gray to black mildew. The disease spot is smaller when the plant is nitrogen deficient, larger when potassium deficiency, and has obvious wheel pattern. When the disease spot is long, a large necrotic area is formed on the leaf, which makes the leaf gradually dry up from the leaf tip to the bottom, and often causes the leaf to die in the later stage. The disease overwinters mainly in mycelium and conidia on the remains of the disease. Bacteria infecting Zizania caduciflora not only requires more than 92% relative humidity, but also requires water droplets. The upper onset period of Zizania latifolia in autumn is from late June to early July, the disease occurs quickly around July 10, the peak occurs from July 20 to early September, the disease slows down after the middle of September, and stops developing in the middle of November. The soil is sour, lack of potassium or zinc, long-term irrigation of deep water hypoxia, extensive management of the field disease is serious. Under the condition of high temperature and high humidity, the continuous cropping field has high planting density, partial application of nitrogen fertilizer, poor ventilation and light transmission in the field, which is easy to induce the disease. In order to prevent the leaf spot of Zizania latifolia and flax, attention should be paid to strengthening field management. (1) rotation. Rotate Zizania caduciflora with lotus root, water chestnut, Cigu, taro and so on. (2) cutting stubble. In winter, the plants of Zizania caduciflora were cut at a height of 1.5 cm above the ground, and the leaves of the residual plants were taken out of the field and burned. (3) fertilization. Wax fertilizer is applied in winter, seedling fertilizer is applied in spring, and foliar fertilizer is sprayed in time. Mainly organic fertilizer, usually 2500-4000 kg per mu. If there is a lack of phosphorus and potassium, pay attention to supplement phosphorus and potassium fertilizer and zinc fertilizer. (4) Pipe water. During the high temperature period from July to August, the water layer is kept at 12-18 cm, and the water is often changed to cool down. Pay attention to shelving the field, after each cultivation until the topsoil is cracked and then irrigated, in order to improve the root activity of Zizania caduciflora. In production, the drug should be used to control the leaf spot of Zizania caduciflora from the late tillering stage or in the early stage of the disease. spray with 1500-2000 times of 25% prochloraz EC, or 1000 times of 50% isobarbazide wettable powder, or 5000-6000 times of Fuxing 40% flusilazole EC, once every 10 days, for 2-3 times continuously.