Lesniak Kimberley E, Proffer Tyre J, Beckerman Janna L, Sundin George W
Department of Plant Pathology, Michigan State University, East Lansing 48824.
Department of Plant Pathology, Michigan State University, East Lansing and Department of Biological Sciences, Kent State University, Salem, OH 44460.
Plant Dis. 2011 Aug;95(8):927-934. doi: 10.1094/PDIS-12-10-0898.
Control strategies for Venturia inaequalis rely heavily on chemical fungicides. Single-site fungicides such as the quinone-outside inhibitors (QoI) have been used in Michigan apple orchards for more than 11 years. In 2008, we sampled eight commercial orchards in the Fruit Ridge growing region of Michigan in which apple scab control failures were observed on 'McIntosh' apple following applications of kresoxim-methyl or trifloxystrobin. QoI resistance was assessed in 210 total isolates (a total of 17 orchards) using a spore germination assay and in 319 isolates using a polymerase chain reaction (PCR) assay to detect the G143A mutation located within the V. inaequalis cytochrome b gene (CYTB). The G143A mutation is known to confer high-level QoI resistance in plant-pathogenic fungi. QoI resistance was confirmed in 50 and 64% of the isolates tested with the spore germination and PCR assays, respectively, and there was a 97% concordance observed between the assays. In 2009, we sampled and examined an additional 1,201 V. inaequalis isolates from 64 orchards in Michigan and 86 isolates from four baseline sites in Ohio. All of these isolates were assayed for the G143A mutation and it was detected within 67 and 0% of the Michigan and Ohio isolates, respectively. Our results indicate the widespread occurrence of QoI resistance in Michigan commercial orchard populations of V. inaequalis. Loss of QoI fungicides further limits the arsenal of fungicides available to commercial apple growers for successful scab management.
苹果黑星病菌的防控策略严重依赖化学杀菌剂。单作用位点杀菌剂，如醌外抑制剂（QoI），已在密歇根州的苹果园中使用了11年以上。2008年，我们在密歇根州水果岭种植区的8个商业果园进行了采样，在这些果园中，对“麦金托什”苹果施用甲氧基丙烯酸酯类杀菌剂（如嘧菌酯或肟菌酯）后，观察到苹果黑星病防治失败。使用孢子萌发试验对总共210个分离株（来自17个果园）进行了QoI抗性评估，并使用聚合酶链反应（PCR）试验对319个分离株进行了检测，以检测苹果黑星病菌细胞色素b基因（CYTB）中的G143A突变。已知G143A突变可使植物病原真菌对QoI产生高水平抗性。分别使用孢子萌发试验和PCR试验检测，在测试的分离株中，QoI抗性在50%和64%的分离株中得到证实，两种试验之间的一致性为97%。2009年，我们从密歇根州的64个果园中另外采集并检测了1201个苹果黑星病菌分离株，以及从俄亥俄州的4个基线地点采集的86个分离株。对所有这些分离株进行了G143A突变检测，分别在密歇根州和俄亥俄州分离株的67%和0%中检测到该突变。我们的结果表明，在密歇根州商业果园的苹果黑星病菌种群中，QoI抗性普遍存在。QoI杀菌剂的失效进一步限制了商业苹果种植者可用于成功防治黑星病的杀菌剂种类。
