大豆疫霉菌对甲霜灵(Metalaxyl)的敏感性及变异性

 大豆疫霉菌(Phytophthora megasperma f.sp.glycinea)对甲霜灵的敏感性及变异性研究结果表明,17个中国大豆疫霉菌侏菌丝生长对甲霜灵较敏感,Ec50值平均为0.0098ppm,Ec95值平均为2.6295ppm。但不同菌株对甲霜灵的敏感性不同,Ec50值范围在0.0042~0.0297ppm之间,相差7倍左右。Ec95值范围在0.7688~6.1682ppm之间,相差8倍左右。3个美国菌株菌丝体生长对甲霜灵有一定耐药性,Ec50值范围在0.3725~0.4813ppm之间,Ec95值范同在125.97~280.59ppm之间,分别比中国大豆疫霉菌株Ec50值和Ec95值平均高43倍和77倍。单孢分离物菌丝体生长对甲霜灵敏感性变异较大,B1菌株单孢分离物Ec50值范围在0.0058~0.2537ppm之间,S367菌株的单孢分离物的Ec50值范围在0.0069~0.1735ppm之间,分别相差43倍和25倍。有的单孢分离物对甲霜灵的耐药性增高。各菌株孢子囊和卵孢子产生对甲霜灵敏感性有一定差异,但1.0ppm的甲霜灵对其抑制率均为100%。活体测定结果表明,1.0ppm的甲霜灵对该病的防效达94~100%。

SENSITIVITY AND VARIABILITY OF PHYTOPHTHORA MEGASPERMA F. SP. GLYCINEA TO METALAXYL

The sensitivity and variability of P. megasperma f. sp. glycinea to metalaxyl were tested in vitro. The results showed that the mycelial growth of 17 strains isolated from China was sensitive to metalaxyl on CA medium. However, the sensitive degrees were different between these strains that the range of Ec50 and Ec95 values were 0.0042~0.0297 ug/ml and 0.7688~6.1682ug/ml. respectively. Meanwhile, the hyphal growth of 3 isolates from U. S. A. was tolerant to metalaxyl in CA medium, in which the range of Ec50 and Ec95 values were 0.3725~0.4818ug/ml and 125.97~280.59ug/ml,respectively. The sensitive degrees of mycelial growth of single spore isolates of B1 and S367 strains to metalaxyl were changeable on CA medium, in which the range of Ec50 values were 0.0058~0.2537 ug/ml and 0.0069~0.1735 ug/ml. The formation of sporangia and oospores of all strains were inhibited by metalaxyl at 1.0 ug/ml on CA medium. The fun-gitoxicity of metalaxyl on P. megasperma f. sp. glycinea was tested in vivo also, the result showed that the systemic protection values of metalaxyl at 1.0 ug/ml was 94% to 100%.