Johnson Kendall A, Douglas Rachel K, Bradshaw Michael J, Brannen Phillip M, Jurick Wayne M, Villani Sara M
Technical Services Division, UPL North America, Wenatchee, WA 98801, U.S.A.
North Carolina Cooperative Extension, Haywood County Center, Waynesville, NC 28786, U.S.A.
Plant Dis. 2025 Mar;109(3):579-592. doi: 10.1094/PDIS-05-24-1006-RE. Epub 2025 Mar 17.
Glomerella leaf spot (GLS), Glomerella fruit rot (GFR), and apple bitter rot (ABR), caused by spp., are among the most devastating apple diseases in the southeastern United States. Although several species have been identified as causal pathogens of GLS, GFR, and ABR, their relative frequency and fungicide sensitivity status in the southeastern United States is unknown. In total, 381 isolates were obtained from symptomatic leaves and fruit from 18 conventionally managed apple orchards and two baseline populations in western North Carolina and Georgia in 2016 and 2017. Multilocus DNA sequence analysis revealed that was the predominant cause of GLS and GFR and was the causal agent of ABR. Baseline and commercial populations of spp. were evaluated for sensitivity to pyraclostrobin and trifloxystrobin, and no statistical differences in sensitivity between the two species were observed for conidial germination. However, the effective concentration that inhibited growth by 50% values were significantly lower for compared with for both fungicides regarding mycelial inhibition. Isolates recovered from commercial orchards revealed that five populations of and one population of had reduced sensitivity to trifloxystrobin, and one population had reduced sensitivity to pyraclostrobin via conidial germination assays. The gene for 27 isolates of , , and with different quinone outside inhibitor (QoI) sensitivities revealed the G143A mutation in a single isolate of with insensitivity to both fungicides. The results of these studies suggest that two spp. predominantly cause GLS and ABR in the southeastern United States and that a reduction in sensitivity to some QoI fungicides may be responsible for control failures. This study also provides a basis for monitoring shifts in QoI sensitivity in spp. causing disease on apple in the southeastern United States.
由[具体菌种]引起的炭疽叶枯病（GLS）、炭疽果腐病（GFR）和苹果苦腐病（ABR）是美国东南部最具毁灭性的苹果病害。尽管已鉴定出几种菌种是GLS、GFR和ABR的致病病原体，但它们在美国东南部的相对频率和对杀菌剂的敏感性状况尚不清楚。2016年和2017年，共从北卡罗来纳州西部和佐治亚州的18个常规管理苹果园以及两个基线种群的有症状叶片和果实中获得了381个分离株。多位点DNA序列分析表明，[某种菌种]是GLS和GFR的主要病因，[另一种菌种]是ABR的病原体。对[相关菌种]的基线种群和商业种群进行了对吡唑醚菌酯和肟菌酯的敏感性评估，在分生孢子萌发方面，未观察到两种菌种之间的敏感性存在统计学差异。然而，就菌丝抑制而言，两种杀菌剂抑制生长50%的有效浓度，[某种菌种]相比[另一种菌种]显著更低。从商业果园回收的分离株显示，通过分生孢子萌发试验，[某种菌种]的五个种群和[另一种菌种]的一个种群对肟菌酯的敏感性降低，[某种菌种]的一个种群对吡唑醚菌酯的敏感性降低。对27个具有不同醌外抑制剂（QoI）敏感性的[相关菌种]分离株的[相关基因]分析显示，在对两种杀菌剂均不敏感的[某种菌种]的一个分离株中存在G143A突变。这些研究结果表明，在美国东南部，两种[相关菌种]主要导致GLS和ABR，对某些QoI杀菌剂敏感性的降低可能是防治失败的原因。本研究还为监测美国东南部苹果上致病的[相关菌种]的QoI敏感性变化提供了依据。
