The disease, also known as mulberry leaf blight, mulberry disease, and bad head disease, is widely distributed and is one of the most important mulberry diseases. There are two types of lesions on the mulberry leaf caused by the disease. It is caused by leaf stomata infestation. It appears as a roundish or irregular semi-transparent spot with oily shape in the early stage of disease. It expands into yellow to yellowish-brown spots after expansion. The surrounding leaves are slightly whitish green. When the climate is dry, the center will perforate; One is caused by the petiole and veins invading from the vascular bundles. The veins of the diseased leaves turn brown, and most of the tiny polygonal lesions are formed by the veins. In the veins and petioles, there are dark, slightly darkened, slender spots. The leaves are shriveled and most of the yellow leaves fall off. When the bacteria invaded the young shoots, the shoots and buds turned black and rotted, forming bad heads. When the disease spreads to the shoots, the spotted brown spots on the diseased branches appear to be dotted with light yellowish beady pus. In severe cases, the lesions can penetrate deep into the branches. Pathogens of the disease overwintered on diseased shoots, diseased shoots, and diseased leaves in the soil. Overwintering causes the onset of buds, and the fungal pus that overflows from the disease later spreads through the rain, splashes on branches and leaves, spreads insects to young shoots, and infects again. Sick seedlings and scions are the main source of infection for long-distance transmission of the disease. The disease is prone to occur when the temperature is 25-30OC and the relative humidity is above 85%. The resistance of different mulberry cultivars to the disease varies greatly. Tongxiang Qing is the most susceptible and the Husang mulberry varieties are more resistant to disease. Low-lying terrain, high groundwater levels, and partial application of nitrogenous fertilizers and branches and leaves are more prone to disease. According to the occurrence characteristics of the disease, the following comprehensive prevention and control measures can be taken in production: (1) Select disease-resistant seed varieties. In accordance with local conditions, it was selected to plant lotus leaf white, cultivar No. 2, Husang 13, Husang 199 and other varieties. (2) Cultivate disease-free seedlings. Do not use sick branches for scioning or cutting, and remove diseased seedlings in time. (3) Clearing the garden to prevent disease. During the winter, the diseased shoots were cut, and the diseased branches were cut off during the summer harvest. The diseased branches and leaves were taken out of the mulberry garden and burned. Dig out the old diseased trees in time and make new ones. (4) Strengthen the pest control work, insist on leaf picking in the summer and autumn to reduce wounds and reduce the incidence rate. (5) Drain the drainage in time to reduce the groundwater level; control nitrogen fertilizer, increase phosphate fertilizer and organic fertilizer. (6) At the beginning of the disease, spray with 15% streptomycin and 1.5% oxytetracycline plus 500 times water, spray once every 7 days, and control 3-4 times. In the disease-prone season, spray 15% copper ammonia fungicide 200 times, every 5-7 days, a total of 2-3 sprays, a better preventive effect.
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