Biological Activity And Resistance Risk In Laboratory Of Pyrimorph To Phyophthora Infestans

Pyrimorph, (E)-3-[(2-chloropyridine -4-yl)-3-(4-tert-butylphenyl)-acryloyl] morpholine, is a novel fungicide developed by College of Sciences, China Agricultural University in 2003. Pyrimorph has a good effect on Phytophthora infestans,Phytophthora capsici and Pseudoperonospora cubensis in vivo and will be popular in the market.Tomato late blight is one of the most serious diseases on China tomato and potato produce. Aimed to control the popularity of tomato late blight, fungicide workers are searching new fungicides for the widely resistance to traditional Oomycete-fungicides occurred in field. So it is essential to figour out the biological activity and resistance risk of pyrimorph.The paper studied pyrimorph had an excellent protective activity. The results showed protective activity of pyrimorph was prior to curative activity in the pot. The control efficacy of pyrimorph against tomato late blight, applied pyrimorph 24 h before inoculating zoospore suspension of Phyophthora infestans at the concentration of 400 and 800 mg/L, were 94.1% and 100%, respectively.The control efficacy of pyrimorph against tomato late blight, applied pyrimorph 24 h after inoculating zoospore suspension of Phyophthora infestans at the concentration of 400, 800 and 1000 mg/L, were 39.3%, 64.9% and 84.7%, respectively.It showed that the protective activity of pyrimorph is prior to that of dimethomorph, but the curative activity of pyrimorph is not as good as that of dimethomorph.The control efficacy of pyrimorph against tomato late blight, applied pyrimorph 1, 3 and 8d at the concentration of 400 mg/L, before inoculating zoospore suspension of Phyophthora infestans, were 94.1%, 90.8% and 78.1%, respectively. The control efficacy of pyrimorph against tomato late blight, applied pyrimorph 1, 3 and 8d at the concentration of 800 mg/L, before inoculating zoospore suspension of Phyophthora infestans, were 100%, 98.4% and 100%, respectively.The result showed the duration of activity of pyrimorph against tomato late blight was more than 8d.Test results indicated the systemic translocation activity of pyrimorph against tomato late bight was lower than its protective activity. Soil treatment by incubating the highest concentration of 2000 mg/L of pyrimorph in the pot, the control efficacy was only 36.1%.Pyrimorph failed to translocate basipetally from leaf to leaf, but showed trans-laminar protection in the intact leaves. Pyrimorph induced obvious alterations in the morphology of hypha of Phyophthora infestans from SEM.Two pyrimorph-resistant mutants were obtained by fungicide adaptation in laboratory. The resistance levels of the 2 pyrimorph-resistant mutants were 1.96 and 5.17. Five pyrimorph-resistant mutants were obtained by UV selection in laboratory. The highest resistance level of the pyrimorph-resistant mutants was 7.66 and the lowest resistance level of the pyrimorph-resistant mutants was 1.53. The mycelial growth rates of pyrimorph-resistant mutants were slower than their parents. The sporangia formation capacity was lower than parental isolates. The resistance level and rate of mycelia growth of subcultures on nonamended medium at low and high temperature in 30d did not change. Based on these results, the character of pyrimorph-resistence mutants were stable.