水稻霜霉病,又叫黄化萎缩病。1890年首先在澳大利亚发现,以后在日本、意大利、美国、印度等国家以及我国的东北、台湾、江苏、广东等省市相继报道此病发生。笔者于1986年9月在山东曲阜城郊发现并鉴定了此病。该病在我省为首次发现,田间发病率为17%。此病呈系统性侵染,一旦发生,发病率基本上等于损失率,对产量影响较大。(一) 症状病株显著矮缩,一般只相当于健株高度的1/2～1/3。病叶褪绿呈淡黄色,心叶黄白色且严重扭曲畸形。病株分 Rice downy mildew, also known as yellow atrophy. First discovered in Australia in 1890, later in Japan, Italy, the United States, India and other countries as well as our country’s northeast, Taiwan, Jiangsu, Guangdong and other provinces have reported the disease. The author in 1986 September in Qufu, Shandong suburbs found and identified the disease. The disease was first discovered in our province, the incidence rate of 17% in the field. The disease is systemic infection, once occurred, the incidence rate is basically equal to the loss rate, a greater impact on the yield. (A) Symptoms Strain significantly dwarfed, generally only the equivalent of a healthy height of 1/2 to 1/3. Sick leaves chlorotic pale yellow heart yellowish white and serious distortion deformity. Strain points