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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％。
The sensitivity and variability of Phytophthora megasperma f. Sp.glycinea to metalaxyl The results showed that the growth of 17 Chinese Phytophthora sojae strains was more sensitive to metalaxyl, the average Ec50 value was 0.0098ppm, The Ec95 value averaged 2.6295 ppm. However, the sensitivity of different strains to metalaxyl is different, the Ec50 values range between 0.0042 ~ 0.0297ppm, a difference of about 7 times. Ec95 value range between 0.7688 ~ 6.1682ppm, a difference of about 8 times. The mycelial growth of three American strains showed some resistance to metalaxyl, the Ec50 values ranged from 0.3725 to 0.4813 ppm, and the Ec95 values ranged from 125.97 to 280.59 ppm, which were respectively higher than Ec50 And Ec95 values were 43 and 77 times higher on average. The mycelial growth of single spore isolates had a large variation in the sensitivity to metalaxyl, the Ec50 value of single spore isolates of strain B1 ranged from 0.0058 to 0.2537ppm, and the isolates from single strain spores of S367 strain ranged from 0.0069 to 0.1735ppm A difference of 43 times and 25 times respectively. Some single spore isolates of metalaxyl resistance increased. Sporangia and oospores of each strain produced some differences in the sensitivity to metalaxyl, but 1.0% metalaxyl had a 100% inhibition rate. The results of in vivo assay showed that 1.0ppm metalaxyl had 94 ~ 100% control effect on this disease.