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向日葵霜霉病是向日葵的一种严重病害,它广泛分布于世界各地。尤以苏联及东欧等国家发生普遍而且严重。我国于1963年刘惕若等首次报导黑龙江省牡丹江地区发生向日葵霜霉病。1980年李玉报导:吉林省自1972年以来,在白城、四平、通化、长春等地区相继发现该病危害向日葵。我们于1980年6月初在铁岭发现向日葵霜霉病。经镜检观察和鉴定,其病原菌为 plasmo-para halstedii(Farlow)Berl et deToni。该菌为霜霉菌科单轴霉属的一种真菌,其孢囊菌梗单轴分枝、无色透明、无隔膜。孢囊梗平均大小为19.6×12.9微米。孢囊梗分枝近直角,小梗末端略钝,其上着生孢子囊。孢子囊亦为无色透明。多为椭圆形、球形或卵圆形,顶端略呈乳头状突起。测定50个孢子囊,平均大小为19.3×16.4微米。初步观察,向日葵霜霉病有以下几种症
Sunflower downy mildew is a serious disease of sunflower, which is widely distributed around the world. In particular, the United States and other countries in the Soviet Union and widespread and serious. In 1963, Liu Ti-ruo et al first reported that sunflower downy mildew occurred in the Mudanjiang area of Heilongjiang Province. In 1980, Li Yu said: Since 1972, Jilin Province has discovered sunflower in the areas of Baicheng, Siping, Tonghua and Changchun. We found sunflower downy mildew in Tieling in early June 1980. After microscopic examination and identification, the pathogen was plasmo-para halstedii (Farlow) Berl et deToni. The fungus is a fungus belonging to the genus Aspergillus of the Downy Mildew family. Its cyst stems are uniaxially branched and colorless and transparent with no membrane. The average cyst size is 19.6 × 12.9 μm. Spore stem branch near right angle, small stem slightly blunt end, on which the sporocyst. Sporangia is also colorless and transparent. Mostly oval, spherical or oval, the tip slightly papillae. 50 sporangia were measured with an average size of 19.3 × 16.4 μm. Preliminary observations, sunflower downy mildew has the following symptoms