Progress in understanding molecular mechanisms and evolution of resistance to succinate dehydrogenase inhibiting (SDHI) fungicides in phytopathogenic fungi

Succinate dehydrogenase (Complex II or succinate-ubiquinone oxidoreductase) is the smallest complex in the respiratory chain and transfers the electrons derived from succinate directly to the ubiquinone pool. Succinate dehydrogenase inhibitor (SDHI) fungicides specifically inhibit fungal respiration by blocking the ubiquinone-binding sites in the mitochondrial complex II and play an important role in the integrated management programmes of many plant diseases. In contrast to first generation of SDHI fungicides (e.g. carboxin) exceptionally active against basidiomycetes, newer active ingredients in this class (e.g. boscalid, penthiopyrad, fluopyram) show a broad-spectrum activity against various fungal species. However, the consistent use of site-specific fungicides such as SDHIs can result in the selection of resistant fungal genotypes which may ultimately lead to a rapid decline of fungicide performance. This paper reviews previous and recent advances in understanding the molecular mechanisms and other factors controlling the evolution of resistance to SDHI fungicides. Furthermore, we provide recommendations on the future use of new developed molecules of this group as well as future research prospects.     

Evaluation of fungicides to control circular leaf spot of persimmon caused by Mycosphaerella nawae

The efficacy of ten fungicides against Mycosphaerella nawae, the causal agent of circular leaf spot (CLS) of persimmon, was evaluated in vitro and in field experiments. Field trials were conducted in 2009 and 2010 to investigate the comparative efficacy of the fungicides alone or combined using alternating sequences in spray programmes based on two, three or four applications. Disease incidence was assessed by estimating the percentage of affected leaves, which included leaves showing at least one necrotic spot and defoliation. Fenpropimorph, pyraclostrobin, tebuconazole and thiophanate-methyl were the most effective fungicides in inhibiting mycelial growth of M. nawae isolates (EC₅₀ < 2 ppm). In field experiments, the most effective fungicides using two spray applications were captan, chlorothalonil, mancozeb and pyraclostrobin which significantly reduced disease incidence compared with untreated plots. Regarding the number of spray applications, two applications of captan and mancozeb were less efficient than three to control the disease. However, the percentage of affected leaves provided by three applications of captan and mancozeb alone or combined with pyraclostrobin using alternating sequences in spray programmes, was not significantly different from that provided by four applications. Experimental results demonstrated that spray programmes based on three applications of these fungicides could effectively control CLS of persimmon. The advantages of spray programmes based on alternated use of strobilurins and protective fungicides are discussed.     

栝楼果实腐烂病病原菌鉴定及防治药剂的筛选

【目的】明确引起栝楼果实腐烂病的病原菌种类并筛选其有效防治药剂。【方法】2019—2020年采集安徽省大别山区的栝楼果实腐烂病样品,采用组织分离法获得35株分离物,利用柯赫氏法则验证其致病性,依据菌株形态学特征和多基因序列分析确定病原菌种类;采用菌丝生长速率法测定7种杀菌剂的室内毒力。【结果】共分离纯化得到4种不同菌落形态特征的菌株,经柯赫氏法则验证均为栝楼果实腐烂病病原菌,经形态学观察和分子系统发育分析,确定引起栝楼果实腐烂病的病原菌分别为藤仓镰孢菌Fusarium fujikuroi、层出镰孢菌F.proliferatum、果生刺盘孢Colletotrichum fructicola和辽宁刺盘孢C.liaoningense,分离频率依次为31.4%、8.6%、20.0%和40.0%。室内毒力测定结果表明,咪鲜胺、咯菌腈、苯醚甲环唑、氰烯菌酯和百菌清对F.fujikuroi和F.proliferatum的抑制效果较好,EC₅₀为0.104 6～5.178 1μg/mL;咪鲜胺、苯醚甲环唑和咯菌腈对C.fructicola和C.liaoningense的抑制效果较...     

新三唑类化合物的生物活性研究

测定了１６个通式为（ＣＨ３）３Ｃ（Ｘ）ＣＨ（Ｔｒ）ＣＨ２（Ｙ）Ｒ的新三唑类化合物「式中,Ｘ＝ＣＯ,ＣＨＯＨ;Ｔｒ＝（１Ｈ）＝－１,２,４－三唑－１－基,＝Ｎ,ＮＨ;Ｒ＝（取代或未取代）苯基,烷基;（五赠或六员）杂环基」对８种病原菌的钉菌活性和促进黄瓜子叶生根植物生长调节活性。比较了１６个新化合物的结构＝生物活性关系。     

5%蒜精油水乳剂对三种棉花致病菌的毒力作用

试验采用生长速率法测试了 5 %蒜精油水乳剂对棉花立枯丝核菌、棉花串珠镰孢菌和棉花尖镰孢萎蔫专化型真菌的室内毒力 ,三者的EC50 分别为 1 9.4mg/L、7.1mg/L、2 0 .6mg/L ,表明 5 %蒜精油水乳剂对 3种病原菌均有明显的抑制作用。试验结果为 5 %蒜精油水乳剂应用于棉花病害的防治提供了依据。     

9种杀菌剂对玉米弯孢霉室内毒力和田间药效试验

采用生长速率法测定了9种有机杀菌剂对玉米新月弯孢霉菌的毒力,并进行了极强毒力杀菌剂的混配试验。结果表明:烯唑醇和扑海因对玉米弯孢霉具有极强毒力,回归曲线的相关系数和EC50值分别为0.973和1.4048E+1和0.965、2.2172E+1。烯唑醇和扑海因以5∶5比例混配不仅表现为强增效作用(共毒系数为147),而且对玉米新月弯孢霉菌丝生长抑制作用最强,菌丝生长相对抑制率为32.30%。利用这两个混配组合进行田间药效试验。结果显示:烯唑醇与扑海因以5:5混配,田间相对防效明显高于两单剂及目前生产中常用于防治玉米弯孢霉叶斑病的百菌清。     

小麦白粉病菌对三唑酮的抗药性测定方法的研究

试验比较了叶段法、小株法、试管苗法、活动苗圃法测定小麦白粉菌对三唑酮药剂的灵敏度的差异，并建立了灵敏度基线，发现了抗药菌株，可供测定小麦白粉菌的抗药性参考。     

果蜡保鲜剂配方优化研究

以富士苹果为试材 ,利用四因素二次通用旋转组合设计法 ,对初选出的保鲜剂 IAA、6 - BA、戴唑霉、TBZ的保鲜效果进行了配方优化组合研究 ,并对选出的优化配方进行了保鲜效果试验。结果表明 ,纳米 Si Ox苹果保鲜果蜡配方为 Si Ox果蜡基蜡 IAA2 0 0 m g/ kg 6 - BA2 0 m g/ kg 戴唑霉 5 0 0 mg/ kg TBZ5 0 0 mg/ kg;纳米Si Ox果蜡基蜡对保鲜剂剂量无显著影响 ,纳米 Si Ox苹果保鲜果蜡在增加果品色泽、亮度及降低果品干耗等性能方面与进口果蜡相近 ,且在防腐烂性能方面优于进口果蜡     

叶菌唑与氟唑菌酰羟胺对小麦赤霉病的复配增效研究

为探索叶菌唑与氟唑菌酰羟胺复配对小麦赤霉病菌的增效作用,采用菌丝生长速率法对两种原药进行室内联合毒力测定。结果显示叶菌唑与氟唑菌酰羟胺质量比为1.5∶1时,增效系数最大。在此基础上进行田间药效试验,结果表明8%叶菌唑悬浮剂70 g/667m²+18%氟唑菌酰羟胺悬浮剂20.7 g/667m²处理的效果最好,防效为83.57%,其次为8%叶菌唑悬浮剂55 g/667m²+18%氟唑菌酰羟胺悬浮剂16.3g/667m²,防效达到78.01%。复配处理中高剂量的防效均显著高于两种单剂的推荐剂量,且试验期间没有对非靶标生物产生影响,建议在生产中使用该剂量。     

不同药剂和包装处理对甜樱桃生理、品质及贮藏性的影响

研究了不同药剂和包装处理对贮藏期间甜樱桃果实生理和品质变化的影响。试验结果表明，包装和药剂处理组合对控制果实腐烂，保持果实硬度和颜色，减缓维生素Ｃ和可滴定酸含量的下降速率，抑制乙烯和乙醇生成都具有较明显的效果。但是药剂和包装处理并不影响贮藏期间果实可溶性固形物的含量。生物 １号药剂与 ０．０４ ｍｍ厚加有ＴＢＺ的聚乙烯塑料薄膜袋配合对减缓果实衰老，减少果实腐烂和保持果实品质的效果最好。