山东省辣椒上尖孢炭疽复合种对吡唑醚菌酯的敏感基线及吡唑醚菌酯增效配方筛选

Baseline sensitivity to pyraclostrobin of Colletotrichum acutatum species complex collected from chili in Shandong Province and the screening of synergistic formula

为明确山东省辣椒炭疽病菌对吡唑醚菌酯的敏感性,延缓其抗性发展及降低防治成本,在该省主要辣椒产区采集并经单孢分离获得175株尖孢炭疽复合种,采用菌丝生长速率法和孢子萌发法测定了病原菌群体对吡唑醚菌酯的敏感性,同时测定了吡唑醚菌酯与甲基硫菌灵、多菌灵、代森锰锌、戊唑醇和咯菌腈5种杀菌剂分别混用对尖孢炭疽复合种的联合毒力。结果表明:吡唑醚菌酯对尖孢炭疽复合种菌丝生长和孢子萌发的EC50值范围分别为0.056~0.530和0.002~0.027μg/m L,平均值为(0.273±0.067)和(0.014±0.019)μg/m L,其敏感性频率分布呈连续单峰曲线,符合正态分布,可作为田间抗性监测的敏感基线;不同采集地菌株对吡唑醚菌酯的敏感性存在一定差异,其中采自菏泽市的菌株敏感性最高,而采自潍坊市的菌株敏感性最低;吡唑醚菌酯与甲基硫菌灵按体积比1:3和3:1复配,对抑制尖孢炭疽复合种的菌丝生长和分生孢子萌发均表现为增效作用,其中按体积比1:3混用时增效作用最明显,增效系数分别是4.82和3.94。结果可为吡唑醚菌酯的合理使用提供理论依据。

To evaluate the sensitivity of Colletotrichum acutatum species complex to pyraclostrobin,delay the development of resistance and reduce the financial cost of controlling chili anthracnose, 175 single-spore isolates of C. acutatum species complex were collected from main chili production regions in Shandong Province. The sensitivities of C. acutatum species complex isolates to pyraclostrobin were determined by using mycelial growth test and spore germination test. At the same time, the jointtoxicities of pyraclostrobin combined with thiophanate-methyl, carbendazim, mancozeb, tebuconazole and fludioxonil against C. acutatum species complex were also assessed by using mycelial growth test and spore germination test. The frequency distributions of EC50 values were unimodal curves, with the average EC50 values of（0.273 ± 0.067） and（0.014 ± 0.019） μg/m L for the inhibition of mycelial growth and spore germination, respectively. Therefore, the data could be employed as the baseline-sensitivity of C. acutatum species complex to pyraclostrobin, and it could be used for the field resistance monitoring.The mean EC50 values were different among the isolates collected from different districts. The isolates from Heze were the most sensitive to pyraclostrobin, while the isolates from Weifang were the least sensitive to pyraclostrobin. The results of joint-action test indicate that the mixtures of pyraclostrobin and thiophanate-methyl at the ratios of 1：3 and 3：1 had synergistic effect on both the mycelial growth and spore germination of C. acutatum species complex. The most obvious synergistic effects were observed for the mixture of pyraclostrobin and thiophanate-methyl at the ratio of 1：3, with synergistic ratios of 4.82 and 3.94 for mycelial growth and spore germination tests, respectively. The results provided a theoretical basis for the long-term reasonable application of pyraclostrobin.