致病疫霉抗药性、交配型和适合度

 在离体条件下,我国马铃薯和番茄上62株致病疫霉中对甲霜灵和恶霜灵抗性菌株占11.29%,平均抗性水平15022倍和24733倍,未发现抗霜脲氰菌株和抗烯酰吗啉菌株。在活体条件下,比利时马铃薯上66株致病疫霉中对甲霜灵和恶霜灵抗性菌株占27.3%,河北省围场、崇礼马铃薯上217株中对甲霜灵和恶霜灵抗性菌株分别占29.0%和32.7%,河北省徐水番茄上88株中仅发现1株抗甲霜灵和恶霜灵。比利时马铃薯上的66株中4株为A2交配型,占6.1%,1株交配型为A1A2,抗甲霜灵。围场、崇礼马铃薯上的73株中6株为A2交配型,占8.2%,6株A2交配型中3株抗甲霜灵和恶霜灵。徐水番茄上的4 4株中3株A2交配型占6.8%。致病疫霉对甲霜灵和恶霜灵具有交互抗性,而2药与霜脲氰或烯酰吗啉之间无交互抗性关系。由于抗性菌株的产孢能力明显较高,田间抗甲霜灵和恶霜灵菌株明显比中间型菌株和敏感菌株的适合度高。

RESISTANCE TO FUNGICIDES, MATING TYPES AND FITNESS OF Phytophthora infestans

In vitro , test shows that metalaxyl (M) and oxadixyl (O) resistant strains of Phytophthora infestans are 11.2% of 62 strains isolated from potato and tomato in China, resistance level on an average is 15 022 fold and 24 733 fold, respectively, no strains resistant either to cymoxanil (C) or to dimethomorph (D) are detected. In vivo , test shows that strains resistant to M and O are 27.3% of 66 strains isolated from potato in Belgium, and strains resistant to M and O are 29.0% and 32.7%, respectively, of 217 strains isolated from potato in Weichang and Chongli, Hebei Province. And only one strain resistant to M and O is found among 88 strains isolated from tomato in Xushui, Hebei Province. Of 66 strains from potato in Belgium, 4 strains with A2 mating type account for 6.1%, and one metalaxyl resistant strain with A2 mating type is detected. Among 73 strains from potato in Weichang and Chongli, 6 strains with A2 mating type are 8.2%, 3 A2 strains resistant to metalaxyl and oxadixyl. 3 A2 strains are 6.8% of 44 strains from tomato in Xushui. Cross resistance in P. infestans is confirmed between M and O, but no cross resistance between C or D and M or O. The field strains resistant to M and O are outstandingly fitter than sensitive or intermediate ones, mainly due to stronger sporulation capacity of the field strains.