内吸杀菌剂甲霜灵对向日葵霜霉菌发育的影响

利用电镜技术研究了内吸杀菌剂甲霜灵对向日葵霜霉菌在寄主向日葵上发育的影响。观察发现甲霜灵引起病菌发生一系列的变化。病菌胞间菌丝细胞内液泡、电子致密体增加，线粒体肿胀畸形；菌丝细胞壁不规则地加厚，部分极度加厚的细胞壁构成了假隔膜，并且在菌丝上还有不规则的突起形成。病菌吸器外间质明显不规则地变宽，其中充满大量电子致密度高的物质：部分吸器体不能正常扩张膨大，发育受阻而成畸形。向日葵霜霉菌的以上变化导致菌丝细胞和吸器的坏死，从而抑制了病菌的进一步发育。

EFFECTS OF SYSTEMIC FUNGICIDE METALAXYL ON THE DEVELOPMENT OF DOWNY MILDEW IN SUNFLOWER

Effects of systemic fungicide metalaxyl on the development of downy mildew in infected sunflower leaves were examined with electron microscopy. The obsetvation showed that the fungicide caused a series of changes in the pathogen. The vacuoles and electon - dense bodies increased in hyphae, and some of mitochondria in hyphae swelled and became malformed. The cell walls of some hyphae were markedly thichened, and extremely thickened wall constituted false septa. Some irregular protrusions were observed on the hyphae. The exhaustorial matrixes were found to be enlarged and contain numerous electrondense material. Some of haustoria did not normally expand and became malformed. It was evident that the cytological changes described above led to the necrosis of hyphal cells and haustoria, which inhibited the further development of the pathogen.