Sensitivity of Corynespora cassicola, causal agent of Corynespora leaf spot of cucumber, to thiophanate-methyl, diethofencarb and azoxystrobin.

123

Section: Discussionmentioning

confidence: 99%

Lack of cross‐resistance to a novel succinate dehydrogenase inhibitor, fluopyram, in highly boscalid‐resistant isolates of Corynespora cassiicola and Podosphaera xanthii

Ishii

Miyamoto²,

Ushio

et al. 2011

123

“…Kyoushizuku, powdery mildew was severe (DS 68.4 ± 5.6) in untreated plots ( Table 2). On this cultivar, the efficacy of ASM was surprisingly low after treatment [1] (30.7% control; three sprays after transplanting) and treatments [2][3][4][5] described above (55.4%, 56.8%, 58.3% and 45.9% control, respectively), but control was higher than after six sprays of the reference fungicide TPN (29.2% control). Growth of plants was inhibited for both cultivars only after treatment [3] with ASM added to the soil at sowing, followed by growth in the phytotron, transplanting and two ASM sprays.…”

Section: Plastic Greenhouse Experiments With Natural Infectionmentioning

confidence: 73%

“…Natsubayashi ( Table 3). All the ASM treatments [1][2][3][4][5] yielded a moderate control against this disease (44.2%, 40.0%, 43.3%, 41.0%, and 43.6% control, respectively), only slightly inferior to the reference TPN (51.3% control). On cv.…”

Section: Plastic Greenhouse Experiments With Natural Infectionmentioning

confidence: 86%

“…On the powdery mildew-tolerant cv. Natsubayashi, treatments 1-4 ([1] three sprays of ASM after transplanting, [2] seed soaking in ASM plus two sprays after transplanting, [3] ASM soil amendment at sowing plus two sprays after transplanting, and [4] two ASM sprays after ASM soil amendment at transplanting) provided 100% control of powdery mildew under low to moderate disease pressure (DS 18.8 ± 36.9 in untreated plots). Treatment [5] (soil amendment with microencapsulated ASM formulations at transplanting plus two ASM sprays) also gave high control activity of 87.2%.…”

Section: Plastic Greenhouse Experiments With Natural Infectionmentioning

confidence: 99%

“…However, soon after their introduction, resistant strains of powdery mildew, downy mildew and C. cassiicola rapidly developed and spread, causing a serious problem for disease control. [1][2][3] More recently, novel succinate dehydrogenase inhibitors such as boscalid and penthiopyrad have been commercialized, but strains resistant to these fungicides have also appeared quickly in populations of C. cassiicola and powdery mildew fungus. [4][5][6][7] Systemic acquired resistance (SAR) is a highly desirable form of resistance that generally provides long-lasting and broad-spectrum resistance in plants.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Systemic resistance inducer acibenzolar‐S‐methyl (ASM) and its microencapsulated formulations: their long‐lasting control efficacy against cucumber diseases and mitigation of phytotoxicity

Ishii

Fujiwara

Nishimura

2018

The use of ASM is a potential integrated pest management-based tactic to control cucumber powdery and downy mildews because its long-lasting efficacy allows the application of typical fungicides to be reduced. The risk for resistance development in mildew pathogens will also be reduced. ASM seed treatment as well as soil amendment with microencapsulated ASM is effective in lowering the risk for the phytotoxicity of this compound. © 2018 Society of Chemical Industry.

Two adjacent mutations in the conserved domain of SdhB confer various resistance phenotypes to fluopyram in Corynespora cassiicola

Shi

Zhu

Sun

et al. 2021

BACKGROUND For Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, a necrotrophic pathogen with a broad host range and a worldwide distribution, resistance to fluopyram has been attributed to mutations in SdhB/C/D subunit of the succinate dehydrogenase (SDH) complex. In our previous study, two point mutations in SdhB from isoleucine to valine at position 280 (I280V) and histidine to tyrosine at position 278 (H278Y) showed different resistance phenotypes to fluopyram and boscalid. This research was conducted to explore the correlation between the mutation of SdhB‐I280V or SdhB‐H278Y and resistance to fluopyram or boscalid and its effect on the fitness characteristics of C. cassiicola. RESULTS The sdhB gene in a succinate dehydrogenase inhibitor (SDHI)‐sensitive C. cassiicola strain (wild type) was successfully replaced with the mutant sdhB gene (GTT at position 280, SdhB‐I280V) or with the mutant sdhB gene (TAC at position 278, SdhB‐H278Y,). Compared with the wild‐type strain, the replacement mutants exhibited significantly different resistance phenotypes, with SdhB‐V280 demonstrating moderate resistance to fluopyram and low resistance to boscalid, while SdhB‐Y278 was supersensitive to fluopyram and very highly resistant to boscalid. Both of the mutants exhibited decreased sensitivity to salt stress and increased SDH activity. These two mutations had no effect on the mycelial growth rate, sporulation ability, pathogenicity in vivo, sensitivity to osmotic stress and oxidative stress, cell wall damaging agents, or SHAM. CONCLUSION Two adjacent mutations in the SdhB gene conferred different resistance phenotypes to SDHIs in C. cassiicola, which is important for the development of alternative antifungal fungicides and fluopyram resistance management. © 2021 Society of Chemical Industry.