In the lower reaches of the Yangtze River, the moderate temperature and humidity are moderate, and the light is good. This creates favorable conditions for breeding and infestation of some germs, often causing certain flowers to be seriously damaged. The symptoms and control methods of several major diseases are now described as follows for timely prevention and treatment. First, powdery mildew 1, symptoms. The main damage leaves, but also infect the petiole, shoots and pedicels, buds, petals and other parts. The victim site first presents a sporadic white powder spot that gradually expands and spreads, and develops rapidly. Under suitable conditions, the entire leaf can be covered for 7-10 days, and the surface of the leaf blade is covered with a layer of white powder like a frost In the same way, the damaged leaves, due to the destruction of the tissue, often make the shoots of the leaves distorted and wilted and rigid, which seriously affects the growth and development of plants and photosynthetic use. Some can't bloom normally, and some even die. Chrysanthemum, Impatiens, Euonymus japonicus, cineraria, dahlias, alfalfa, crape myrtle, honeysuckle, zinnia, rose and other flowers are vulnerable. 2, control methods. Strengthen cultivation management. Powdery mildew is severely affected by high temperature and humidity, poor ventilation, and stifling heat. Therefore, the pot should be placed in a place with good ventilation and light transmission. Pay attention to the application of phosphorus and potassium fertilizers, avoid partial nitrogen fertilizer, watering can not be excessive. And timely removal of diseased leaves, cut diseased branches, disease buds. Pull out the diseased plants, concentrate burned, and reduce the re-infection pathogens. At the onset of illness, a 1:1:140 equal amount of Bordeaux mixture may be sprayed. After onset, 25% triadimefon wettable powder 1000 times, or 70% thiophanate-methyl wettable powder 1000 times may be sprayed. In severe cases, spray once every 10 days or so for 2-3 consecutive times. Second, brown spot 1, symptoms. The main damage leaves. At the early stage of disease, brown spots appeared on the leaves. Later, with the continuous development of the disease, the lesions gradually expanded and became large spots. Due to the limitation of veins, they were mostly irregular. A faded halo surrounds it. The edges are reddish-brown and gray-white in the center, and black dots (conidia) are produced in later lesions. When the disease is serious, the lesions occupy the entire leaf. The leaves of the injured plants are easy to fall off, and the victims suffer from heavy damage. The whole plant leaves no leaves, forming light poles, and finally the plants gradually die from the bottom up. Among them, rhododendron, narcissus, jasmine, clove, sweet-scented osmanthus, sticky sea bream, lotus, water lily, heather and other flowers are seriously damaged. 2, control methods. The sick leaves were cut off in time and burned in a concentrated manner to reduce pathogens. Before the onset of illness, a 1:1:200 Bordeaux mixture is sprayed every 7-10 days, which can play a preventive role. At the beginning of the disease, 65% Zeoxin WP can be sprayed 500 times, or thiophanate-methyl 1000 times. Can also be used 50% carbendazim 200 times Irrigation. Third, anthrax 1, symptoms. The disease mainly occurs on the leaves and can also invade the petiole, shoots, stems and bud petals. After the leaves were damaged, they showed tiny, round, pale, water-soaked dots at the beginning, and gradually expanded to gray-brown with brown edges and micro-uplifts. The center of the lesion eventually faded from gray to white. The disease was extremely thin, translucent and easy to perforate. Some also develop from the tip of the leaf and then spread to the inside of the leaf. Lesions often reach 1/3--1/2 of the entire leaf surface, and the last leaves die. Some continue to fall off, and plants that are seriously affected are often absent from all plants. When the petiole is damaged, the diseased part becomes brown, slightly depressed, spreads to the leaves and spreads to the main vein, branch veins and even the whole leaf becomes brown. The lesions continue to spread downwards, from the petiole to the total petiole, branchlets, and even the stems turn brown and die. In wet conditions, pale red mucilage is often produced on lesions, which is a spore plate produced by pathogens. Affected plants, light affect the normal growth and development, loss of ornamental value, resulting in the death of the whole plant. Camellia, rose, Milan, white orchid, lily, Guangyulan, Nandina, Evergreen, Clivia, cactus, plum, orchid and other flowers prone to this disease. 2, control methods. Strengthen the cultivation and management, appropriate application of phosphorus, potassium fertilizer, avoid partial nitrogen fertilizer, watering should not be too much, basin soil should not be too wet, while enhancing air and light transmission performance, reduce humidity. The diseased leaf and diseased leaf stalk should be immediately cut off and burned, and the dead plants should be promptly removed. At the time of onset, it can spray 50% anthrax omeprazole WP 500 times or 70% thiophanate-methyl 1000 times, and 75% chlorothalonil 800 times, spray once every 10-15 days, continuous spray 2- 3 times, alternating use of medicaments can improve the control effect. 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