水稻霜霉病的发生与防治

Occurrence and Control of Dow ny Mildew of Rice

水稻霜霉病的发生与环境因素、栽培情况等有关。在秧田后期和本田前期发病重，大田病株多从秧田传入；秧田水淹、暴雨或连阴雨发病严重，淹水后15～20 d发生，低温有利于发病。农业防治措施包括选择地势较高地块作为秧田，建好排水沟；发现病株即时拔除，集中作堆肥或烧毁；增施有机肥，并做到平衡施肥，防止偏施氮肥；水旱轮作；避免秧田及本田灌深水或淹水传病。化学防治措施包括用0.1%硫酸铜溶液浸种6～8 h ；播种后，用硫酸铜1 g/m^2的稀释液浇施于秧田土面；并在发病早期喷药保护。

Occurrence of downy mildew of rice is related to environmen-tal factors and cultivation conditions.In the late seedling stage and early field stage, seedlings are more vulnerable to the disease; flood, rainstorm or continu-ous raining aggravates the disease, and the disease breaks out especially 15-20 days after being flooded.Agricultural control measures include building nurs-eries on higher terrains, and preparing drainage ditches; removing diseased plants timely by composting or burning;applying more organic fertilizer, avoiding excessive application of nitrogenous fer-tilizer; promoting rice field-upland field rotation; avoiding deep water irrigation. Chemical control measures include soak-ing seeds in 0.1% cupric sulfate solution for 6-8 hours; spraying cupric sulfate diluent 1 g/m^2 on soil surface of nursery;spraying 1∶1∶240 Bordeaux mixture;and adopting fungicide control in the the early period.