辽宁省稻瘟病菌对肟菌酯敏感性监测

 为了明确稻瘟病菌对肟菌酯的敏感性,利用菌丝生长速率法测定了2018~2019年辽宁省11个水稻产区分离的220株稻瘟病菌对肟菌酯的敏感性,并在此基础上对供试菌株的抗药性水平进行了分析。结果表明:稻瘟病菌对肟菌酯的EC₅₀值分布范围为0.011 1～0.498 3 μg·mL^-1,敏感性差异达44.89倍。220株稻瘟病菌对肟菌酯的敏感性分布频率不符合正态分布,说明已经出现对肟菌酯敏感性降低的分化群体,根据野生敏感型病原群体对药剂敏感性呈正态分布的原理,将供试群体中91.82%符合正态分布菌株的平均EC₅₀值(0.043 0±0.017 9) μg·mL^-1作为稻瘟病菌对肟菌酯的敏感性基线。辽宁省稻瘟病菌对肟菌酯的抗性倍数分布范围为0.256 9~11.493 8,平均抗性指数为0.27,抗性菌株出现频率为6.82%。目前菌群以敏感性群体为主,肟菌酯可作为防治稻瘟病的主要药剂,但在多地发现抗性菌株,应注意与不同作用机制药剂轮换使用。

Sensitivity detection of Magnaporthe oryzae to trifloxystrobin in Liaoning Province

To determine the sensitivity of Magnaporthe oryzae to trifloxystrobin, 220 M. oryzae isolates, obtained from 11 rice producing regions in Liaoning Province during 2018 and 2019, were tested by mycelium growth rate method. Then the resistance level of the tested isolates was analyzed. The results showed that the EC₅₀ values of M. oryzae to trifloxystrobin ranged from 0.011 1 to 0.498 3μg·mL^-1. The difference between the highest EC₅₀ value and the lowest EC₅₀ value was 44.89 times. The sensitivity distribution frequency of M. oryzae to trifloxystrobin did not conform to the normal distribution, suggesting that the population with decreased sensitivity to trifloxystrobin was emerged. According to the theory that the sensitivity of wild sensitive pathogens to fungicides was normally distributed, the average EC₅₀ value of 91.82% strains ((0.043 0±0.017 9) μg·mL^-1) which were conform to normal distribution, was used as the baseline sensitivity of M. oryzae to trifloxystrobin. The range of the resistance ratio of M. oryzae to trifloxystrobin in Liaoning Province was from 0.256 9 to 11.493 8 with the average value at 0.27, and the frequency of resistant isolates was 6.82%. At present, most isolates were sensitive to trifloxystrobin and the fungicide can be used as the main fungicide to control rice blast. However, the resistant strains have been found in some regions, which indicated that the alternate fungicides with different mechanisms should be used in turn with trifloxystrobin.