Synthesis and fungicidal activity of ethaboxam against Oomycetes

This study describes the chemical synthesis and intrinsic fungicidal activity of ethaboxam [(RS)-N-(alpha-cyano-2-thenyl)-4-ethyl-2-(ethylamino)-1,3-thiazole-5-carboxamide], a new Oomycetes fungicide. In in vitro tests, ethaboxam showed inhibitory activity against isolates of Phytophthora and some Pythium spp, with MIC values ranging from 0.1 to 0.5 mg litre(-1) for nine isolates of Phytophthora infestans (Montagne) de Bary and from 1.0 to 5.0 mg litre(-1) for eight isolates of Phytophthora capsici Leonian. In tests to determine time and concentration for complete inactivation of each pathogen (five isolates of P infestans and five isolates of P capsici), ethaboxam inactivated all isolates of P infestans within 48h at 10 mg litre(-1) and those of P capsici within 96 h at 10 mg litre(-1). Ethaboxam effectively suppressed development of tomato late blight caused by P infestans and pepper Phytophthora blight caused by P capsici in the studies conducted to determine its preventive, curative, persistent and systemic activity. These results show that ethaboxam has desirable fungicidal characteristics as an Oomycetes fungicide.     

In vivo effects of the fungicide ethaboxam on microtubule integrity in Phytophthora infestans

The effects of ethaboxam (LGC-30473), a novel thiazole carboxamide, on microtubule organization was investigated in Phytophthora infestans (Mont) de Bary (Oomycota) at the light microscope level using standard immunofluorescence and laser scanning confocal microscopy. Hyphal cells were exposed to various concentrations ranging from 0.01 to 1.0 microg ml(-1) of ethaboxam at incubation times of 30, 60 and 120 min. Microtubules were disrupted after exposure to ethaboxam for 30 min at 0.01 microg ml(-1). Similar experimental conditions were used to document the effects of ethaboxam on microtubule integrity in the model fungus Aspergillus nidulans (Eidam) Winter (Ascomycota) and in mammalian mouse 17 clone 1 cells. Under these conditions, there was no evidence to suggest that microtubules in A. nidulans and mouse culture cells were affected by the ethaboxam. These results indicate that ethaboxam is specific for the targeting of microtubule disruption in P. infestans.     

马铃薯晚疫病菌对3种杀菌剂的抵抗性与交配型分化

对采自黑龙江省和吉林省的马铃薯晚疫病菌进行了交配型的测定。结果表明,来自吉林省龙井市和黑龙江省5个县市的67个菌株均为A1交配型,未发现A2交配型。为了筛选对晚疫病有效的杀菌剂,在室内测定了不同杀菌剂的抗药性。马铃薯晚疫病菌对杀菌剂的抗性的测定结果显示,对于瑞毒霉,5个菌株敏感,占8.8%;10个菌株中抗,占17.5%;42个菌株是抗性菌株,占73.7%。对于韩乐威没有菌株能在1.0μg·mL-1的浓度生长,只有1株菌株在0.5μg·mL-1上生长,表明韩乐威的最低抑制浓度是0.2～0.5μg·mL-1。对于烯酰吗啉,大多数菌株能在0.5μg·mL-1的浓度上生长,在1.0μg·mL-1上生长的有2个菌株,表明烯酰吗啉的最低抑制浓度是0.5～1.0μg·mL-1,并且3种杀菌剂没有产生交互抗性。