Baseline sensitivity and control efficacy of fluazinam against Sclerotinia sclerotiorum

Sclerotinia stem rot caused by Sclerotinia sclerotiorum is an important disease of oilseed rape in Henan province of China. Boscalid belongs to succinate dehydrogenase inhibitor (SDHI) fungicides, many of which have strong antifungal activity against S. sclerotiorum. In 2015, a total of 175 isolates of S. sclerotiorum were collected from diseased oilseed rape plants in seven different regions of Henan Province. The EC50 values of 175 isolates of S. sclerotiorum to boscalid ranged from 0.0073 to 0.3880 μg ml−1, and the mean EC50 value was 0.15 ± 0.09 μg ml−1. The frequency distribution was unimodal. There was no cross‐resistance between boscalid and carbendazim, procymidone, iprodione, dimethachlone, fludioxonil or fluazinam. Field experiments showed that control efficacies of treatments with boscalid (50% WG) at 225, 300 and 375 g ai ha−1 were 71%, 81% and 90%, respectively. In contrast, the control efficacy of carbendazim (50% WP) at 1,500 g ai ha−1 was only 52%.

Section: Discussionmentioning

confidence: 99%

Sensitivity to boscalid in field isolates of Sclerotinia sclerotiorum from rapeseed in Henan Province, China

Liu

Hai

et al. 2017

“…The eight putatively resistant isolates were assessed further to determine their EC 50 values (effective concentration inhibiting 50% of colony growth) by culturing them on PDA amended with fenhexamid at a range of concentrations (0, 0.25, 0.5, 1, 2, 4, 8, 16, 32 and 64 μg/ml) according to the protocol of a previous study (Liang, Di, & Li, ). Each treatment consisted of three replicate plates, and the entire experiment was conducted twice.…”

Section: Methodsmentioning

confidence: 99%

Occurrence of fenhexamid resistance in Botrytis cinerea from greenhouse strawberries in China

Zhou

Lü

Zhang

et al. 2017

This study assessed the fenhexamid sensitivity of 143 Botrytis cinerea isolates collected from greenhouse strawberries in five regions of China between 2012 and 2013, and identified four isolates with moderate levels of resistance: two from the Xinjiang Uygur Autonomous Region and two from Hebei Province. The baseline fenhexamid sensitivity of B. cinerea exhibited a unimodal distribution with a mean EC50 value of 0.20 ± 0.10 μg/ml (SD). The EC50 values of the fenhexamid‐resistant isolates ranged from 0.05 to 0.40 μg/ml. Molecular analysis of the fenhexamid target gene erg27 revealed that the resistant isolates collected from Xinjiang (163‐6 and 163‐22) contained three mutations that led to amino acid changes (V365A, E368D and A378T) known to be associated with fenhexamid resistance, but that the isolates from Hebei lacked any mutations, indicating that an alternative mechanism could be responsible for their resistance. Most of the biological characteristics of the fenhexamid‐resistant isolates, such as mycelial growth, sclerotia production and pathogenicity, did not significantly differ from those of the sensitive ones (p ≤ .05), but it was noted that some of the resistant isolates exhibited reduced rates of sporulation and spore germination. In addition, the resistant isolates exhibited lower osmotic sensitivity than the sensitive ones. The study found no evidence of cross‐resistance with other fungicides, but that there was negative cross‐resistance with procymidone, iprodione, carbendazim and pyraclostrobin, which indicates that the inclusion of these fungicides within an integrated pest management (IPM) programme could help to minimize the risk of fenhexamid resistance developing in B. cinerea.

“…Fluazinam is among the phenylpyridinamine fungicides with broad‐spectrum activities in Phytophthora infestans, Sclerotinia sclerotiorum, Ustila gomaydis, Bipolaris maydis and Fusarium fujikuroi (Anema, Bouwman, Komyoji, & Suzuki, ; Chen et al, ; Lehner, Del Ponte, Gugino, Kikkert, & Pethybridge, ; Liang, Di, Li, & Zhu, ; Liu, Jiang, Che, Tian, & Chen, ; Mao et al, ; Qu et al, ; Shao, Ren, et al, ; Vitoratos, ; Wang, Duan, & Zhou, ). Previous studies showed that fluazinam exhibited high fungicidal activity against B. cinerea in mycelial growth (Shao, Ren, et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies showed that fluazinam exhibited high fungicidal activity against B. cinerea in mycelial growth (Shao, Ren, et al, ). Although fluazinam has been registered for the control of Sclerotinia stem rot and grey mould in China since 2014, it is a low‐risk fungicide for resistance, and the fluazinam‐resistant isolate of B. cinerea is yet to be found in fields in China (Liang et al, ; Shao, Ren, et al, ). In other regions of China, the baseline sensitivity to fluazinam has been established in S. sclerotiorum , F. fujikuroi and B. cinerea (Qu et al, ; Shao, Ren, et al, ; Wang et al, ).…”

Section: Introductionmentioning

confidence: 99%

Baseline sensitivity of Botrytis cinerea to fluazinam and cross‐resistance

Liu

Chen

et al. 2019

Grey mould, caused by the fungus Botrytis cinerea Pers ex Fr., is a very destructive and important disease worldwide. Fluazinam is a phenylpyridinamine fungicide with broad‐spectrum activities. The baseline sensitivity of B. cinerea to fluazinam is yet to be established in Henan Province, China. In this study, a total of 117 field isolates of B. cinerea were collected from 49 commercial greenhouses in different locations of Henan Province, in 2016, and the sensitivities of these isolates to fluazinam were determined based on mycelial growth. The effective concentration for 50% (EC50) values ranged from 0.0038 to 0.0441 μg/ml, and the mean EC50 value was 0.0201 ± 0.0081 μg/ml for mycelial growth. The frequency distribution range presented a unimodal curve. To define the cross‐resistance relationships, the linear correlation coefficients of the EC50 values between fluazinam and carbendazim, procymidone, pyrimethanil or boscalid were analysed. The results showed that no correlation was observed between fluazinam and the other tested fungicides. These results provide important information to growers for the prevention and control of grey mould.