Wise K A, Bradley C A, Pasche J S, Gudmestad N C
Department of Plant Pathology, North Dakota State University, Fargo 58105.
Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave., Urbana 61801.
Plant Dis. 2009 May;93(5):528-536. doi: 10.1094/PDIS-93-5-0528.
Ascochyta blight, caused by Ascochyta rabiei (teleomorph: Didymella rabiei), is an important fungal disease of chickpea (Cicer arietinum). A monitoring program was established in 2005 to determine the sensitivity of A. rabiei isolates to the QoI (strobilurin) fungicides azoxystrobin and pyraclostrobin. A total of 403 isolates of A. rabiei from the Northern Great Plains and the Pacific Northwest were tested. Ninety-eight isolates collected between 2005 and 2007 were tested using an in vitro spore germination assay to determine the effective fungicide concentration at which 50% of conidial germination was inhibited (EC) for each isolate-fungicide combination. A discriminatory dose of 1 μg/ml azoxystrobin was established and used to test 305 isolates from 2006 and 2007 for in vitro QoI fungicide sensitivity. Sixty-five percent of isolates collected from North Dakota in 2005, 2006, and 2007 and from Montana in 2007 were found to exhibit a mean 100-fold decrease in sensitivity to both azoxystrobin and pyraclostrobin when compared to sensitive isolates, and were considered to be resistant to azoxystrobin and pyraclostrobin. Under greenhouse conditions, QoI-resistant isolates of A. rabiei caused significantly higher amounts of disease than sensitive isolates on azoxystrobin- or pyraclostrobin-amended plants. These results suggest that disease control may be inadequate at locations where resistant isolates are present.
由菜豆壳二孢菌（有性型：菜豆亚隔孢壳菌）引起的褐斑病是鹰嘴豆（鹰嘴豆属）的一种重要真菌病害。2005年设立了一个监测项目，以确定菜豆壳二孢菌分离株对QoI（甲氧基丙烯酸酯类）杀菌剂嘧菌酯和吡唑醚菌酯的敏感性。共检测了来自大平原北部和太平洋西北部的403个菜豆壳二孢菌分离株。对2005年至2007年收集的98个分离株进行了体外孢子萌发试验，以确定每种分离株-杀菌剂组合抑制50%分生孢子萌发的有效杀菌剂浓度（EC）。确定了1 μg/ml嘧菌酯的鉴别剂量，并用于检测2006年和2007年的305个分离株的体外QoI杀菌剂敏感性。与敏感分离株相比，2005年、2006年和2007年从北达科他州以及2007年从蒙大拿州收集的分离株中，有65%对嘧菌酯和吡唑醚菌酯的敏感性平均降低了100倍，被认为对嘧菌酯和吡唑醚菌酯具有抗性。在温室条件下，菜豆壳二孢菌的QoI抗性分离株在嘧菌酯或吡唑醚菌酯处理过的植株上引起的病害量明显高于敏感分离株。这些结果表明，在存在抗性分离株的地区，病害防治可能不足。
