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Red maple leaf blight
Red maple leaf blight, red maple leaf blight, is a common disease in the growth of red maple. It is widespread and serious. After the onset of the disease, it not only affects the normal growth and development of the plant and the ornamental effect, but also results in the death of the diseased plant. At the onset of symptoms, leaf spots on the tip of leaves and leaves on the upper part of the leaves produced water-stained, chlorotic spots. Since then, as the disease progressed, the diseased parts appeared scorch-like and gradually spread to the lower and inner parts of the leaves. The upper part of the blade died. The junction between the diseased part and the health part was reddish-brown, and the middle part was dark red. Finally, 3/4 of the entire leaf had died. Only the base of the leaf blade was green. The part that died was curled and the tip of the leaf curled. It was grayish white and the leaves of the whole plant were burning. As the leaves lose chlorophyll, they seriously affect photosynthesis and make the plants grow weak and lose their ornamental value. The regularity of the disease is caused by the infection of the fungus Mycelium of the genus Demiomycetes. The pathogenic bacteria wintered in the diseased leaf with a conidia. In the spring of the following year, the temperature rises to produce conidia, and it is transmitted through the rain and air flow, especially the rain on the ground. It is an important communication medium. Since the occurrence of disease is closely related to rain, it will be repeatedly infested in rainy seasons. In general, from July to October, the incidence is the heaviest. In addition, poor soil drainage performance, high humidity, and partial application of nitrogen fertilizer can also lead to severe disease. At the turn of the summer and autumn, under high temperature and strong light conditions, the plants are exposed to the sun and the leaves are burned, which will aggravate the development of the disease. Control methods 1. Strengthen cultivation management. In the fertilization, avoid partial nitrogen fertilizer, appropriate application of phosphorus and potassium fertilizer, promote plant growth robust, and enhance disease resistance. Usually watering should not be excessive, but can not let pot earth long-term water, at the same time to combine fertilization, often loose soil, enhance pot gas permeability, ensure the normal growth and development of root system, improve absorption function. At the end of the fall, the diseased leaves are removed and burned in a timely manner to reduce the pathogenic bacteria that pass through the winter. In the summer and autumn high season, the pots should be placed under scattered light, well-ventilated and shaded areas to prevent exposure. 2. Chemical control. Before the beginning of the disease has not yet spread before the first cut leaves, reduce the re-infection source, and then use 50% carbendazim 500 times or 65% dexamethasone, Fumei Zn 1000 times or 45% dexamethasone 800 times, each Spray alternately for 10 to 15 days and spray 2 to 3 times. (Source: China Flower Network Wang Yougong)