重庆北碚地区发生桑树轮纹病的调查与防治方法

Investigation and Prevention of Mulberry Ring Sheath Disease in Beibei District of Chongqing

桑轮纹病属于真菌病害,近年来重庆市多个蚕区的桑园均有发生为害。调查桑树轮纹病在重庆北碚地区的发生时间一般在9~10月份,桑叶受病原菌侵染后产生大小不等呈淡黄色和红褐色鲜明的同心轮纹,最终导致叶片龟裂、穿孔;5个主栽桑品种的抗病性有差异,其中北桑1号发病率最高,新一之涑页的发病较低;温暖湿润的气候环境及低干密植桑园较易发生病害。连续多年的田间试验表明,保持桑园的通风透光性能、合理施肥增强树势、冬季做好清园工作能在一定程度上减轻病害发生;桑树夏伐疏芽结束后,用70%甲基硫菌灵可湿性粉剂1000倍稀释液喷施新梢,每10 d施药1次,连续施药3次,基本上可以控制该病害的发生。

The fungal disease mulberry ring sheath has been affecting mulberry gardens in many silkworm breeding areas in Chongqing in recent years.According to the investigation,mulberry ring spot disease in Chongqing typically occurs from August to October.Infected mulberry leaves develop concentric rings of varying sizes in bright yellow and reddish brown,eventually leading to leaf cracking and perforation.The resistance levels varied among the five main mulberry varieties,with Beisang No.1 exhibiting the highest incidence and Xinyizhilai showing the lowest susceptibility.The disease is more likely to occur in warm and humid climate and low dry density mulberry plantation.The field experiments over many years have shown that maintaining ventilation and light transmission in the mulberry orchard,fertilizing appropriately to enhance tree vigor,and clearing the orchard well in winter can somewhat reduce disease occurrence.After mulberry summer thinning,spraying the new shoots with a 70%methyl thiourea wettable powder diluted solution(1:1000)every 10 days for three consecutive times effectively prevents disease occurrence.