Liu Yangxi, Del Rio Mendoza Luis E, Qi Aiming, Lakshman Dilip, Bhuiyan M Z R, Wyatt Nathan, Neubauer Jonathan, Bolton Melvin, Khan Mohamed F R
Department of Plant Pathology, North Dakota State University, Fargo, ND 58108, U.S.A.
School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, U.K.
Plant Dis. 2023 Sep;107(9):2825-2829. doi: 10.1094/PDIS-11-21-2583-RE. Epub 2023 Sep 19.
Cercospora leaf spot (CLS) is a destructive disease limiting sugar beet production and is managed using resistant cultivars, crop rotation, and timely applications of effective fungicides. Since 2016, its causal agent, , has been reported to be resistant to quinone outside inhibitors (QoIs) and to have reduced sensitive to demethylation inhibitors (DMIs) in sugar beet growing areas in North Dakota and Minnesota. Isolates of resistant to QoIs, DMIs, and both QoIs and DMIs were collected from fields in Foxhome, Minnesota, in 2017. Fitness of these resistant isolates was compared with that of QoI- and DMI-sensitive isolates in laboratory and greenhouse studies. In the lab, mycelial growth, spore production, and spore germination were measured. The results showed that resistant isolates had significantly less mycelial growth and spore production than sensitive isolates, while no significant difference in spore germination was detected. In the greenhouse, six leaf-stage sugar beets were inoculated with a spore suspension made from each resistant group and incubated in separate humidity chambers. CLS disease severity was evaluated visually at 7, 14, and 21 days after inoculation (DAI), and the areas under disease progress curve (AUDPC) were calculated. Resistant isolates had significantly smaller AUDPC but still caused as high disease severity as the sensitive ones at 21 DAI. Although QoI- and/or DMI-resistant isolates had a relatively slower disease development, they still caused high disease severity and need to be factored in disease management practices.
尾孢叶斑病（CLS）是一种限制甜菜生产的毁灭性病害，可通过使用抗病品种、轮作以及及时施用有效的杀菌剂来进行防治。自2016年以来，据报道其病原菌在北达科他州和明尼苏达州的甜菜种植区对醌外抑制剂（QoIs）产生了抗性，并且对脱甲基抑制剂（DMIs）的敏感性降低。2017年，从明尼苏达州福克斯霍姆的田间采集了对QoIs、DMIs以及同时对QoIs和DMIs都具有抗性的病原菌分离株。在实验室和温室研究中，将这些抗性分离株的适应性与对QoI和DMI敏感的分离株进行了比较。在实验室中，测量了菌丝生长、孢子产生和孢子萌发情况。结果表明，抗性分离株的菌丝生长和孢子产生明显少于敏感分离株，而在孢子萌发方面未检测到显著差异。在温室中，用每个抗性组制成的孢子悬浮液接种六叶期甜菜，并在单独的湿度箱中培养。在接种后7天、14天和21天（DAI）目测评估CLS病害严重程度，并计算病害进展曲线下面积（AUDPC）。抗性分离株的AUDPC明显较小，但在接种后21天仍造成与敏感分离株一样高的病害严重程度。尽管对QoI和/或DMI具有抗性的分离株病害发展相对较慢，但它们仍会导致较高的病害严重程度，因此在病害管理实践中需要考虑到这一点。
