Elsevier

Crop Protection

Volume 158, August 2022, 105989
Crop Protection

Baseline-sensitivity of Botrytis cinerea to pydiflumetofen and its efficacy on tomato gray mold in Hebei Province, China

https://doi.org/10.1016/j.cropro.2022.105989Get rights and content

Highlights

  • Establishment the baseline-sensitivity of Botrytis cinerea to pydiflumetofen.

  • Clarify the cross-resistance relationship between pydiflumetofen and other six botryticides.

  • Pydiflumetofen has good preventive-activity and curative-activity on TGM.

  • Pydiflumetofen is an excellent fungicide for controlling TGM.

Abstract

Tomato gray mold (TGM), a worldwide destructive disease, is caused by Botrytis cinerea, and fungicide treatments are effective for its control. Pydiflumetofen is a new fungicide of succinate dehydrogenase inhibitors. In this research, 153 B. cinerea isolates were collected from eight different cities in Hebei Province from 2015 to 2017. The sensitivity of these 153 isolates to pydiflumetofen was determined by spore germination assays and mycelial growth rate assays. The results indicated that for these tested isolates, the EC50 values of pydiflumetofen ranged from 0.0036 to 0.0822 mg/L (on conidia germination), and 0.0287–1.2659 mg/L (on mycelial growth rate), with average EC50 values of 0.0327 ± 0.0213 mg/L and 0.3717 ± 0.2744 mg/L, respectively. The frequency distribution of the sensitivity of these 153 isolates to pydiflumetofen was a continuous single-peak curve, and could be used as the baseline for testing the sensitivity of B. cinerea to pydiflumetofen. No cross-resistance existed between pydiflumetofen and the other six botryticides such as diethofencarb, pyrimethanil, iprodione, pyrisoxazole, and fludioxonil, apart from fluopyram. The control efficacy of pydiflumetofen against TGM was determined using detached leaves and in field trials. Pydiflumetofen exhibited good control efficacy against TGM and the preventive effect was better than the curative effect. In the field trials, the control efficacy of pydiflumetofen against TGM was higher than 80%, both on leaves and fruits, at doses of 120, 160 and 200 g a.i./ha. It was significantly better than pyrimethanil. This study showed that pydiflumetofen had high activity and could effectively control the prevalence of TGM, but it should be administered carefully.

Introduction

Gray mold is caused by Botrytis cinerea. It not only infects the stem and leaf of tomato, but also infects the flower and fruit, causing a huge decrease in yield. Tomato gray mold (TGM) is a destructive disease in greenhouses worldwide. In agricultural production, the management of TGM mainly relies on the use of chemical fungicides, due to the lack of resistant varieties. However, B. cinerea, classified as a “high-risk” pathogen (Veloukas and Karaoglanidis, 2012), has produced resistance to many fungicides, such as pyrimethanil, diethofencarb, and iprodione (Liu et al., 2016; Zhao et al., 2019). In order to effectively control TGM, it is urgent to develop fungicides with novel mechanisms of action.

Pydiflumetofen, developed by Syngenta, is a broad-spectrum fungicide (Breunig and Chilvers, 2021). It is a new succinate dehydrogenase inhibitor (SDHI) fungicide (Fig. 1), which inhibits the growth of many plant pathogens by interrupting fungal respiration.

Thus far, in China, pydiflumetofen has been registered for the control of fusarium head blight in wheat and stem rot disease in oilseed (www.chinapesticide.org.cn/hysj/index.jhtml). But few studies have reported its activity and efficacy against B. cinerea. So, this study aimed to achieve the following: (a) establish the baseline of the sensitivity of B. cinerea against pydiflumetofen, in Hebei Province of China; (b) clarify the cross-resistance relationship between pydiflumetofen and the six other botryticides; (c) test the preventive and curative control efficacies of pydiflumetofen against TGM on tomato leaves; and (d) assess the control efficacy of pydiflumetofen against TGM in a greenhouse.

Section snippets

Fungal isolates

Diseased leaves and fruits with classical symptoms of TGM were obtained from 8 regions in Hebei province, China. All the isolates of B. cinerea were isolated from leaves and fruits with classical symptoms of TGM, using a previously described method (Zhao et al., 2019) and stored at 4 °C. A total of 153 isolates (Table S1), which collected from the areas pydiflumetofen had never been used, were used to establish the sensitivity baseline of B. cinerea to pydiflumetofen.

Five of the 11

On the growth of mycelium

Pydiflumetofen showed a strong inhibitory activity on the mycelial growth of B. cinerea (Fig. 2). By mycelial growth assay (Table 1), the 153 isolates, collected from 8 cities in Hebei Province, China, showed similar sensitivity to pydiflumetofen. The sensitivity frequency distribution of these 153 isolates to pydiflumetofen was a continuous single-peak curve (Fig. 3). The pydiflumetofen EC50 values of the 153 isolates were 0.0287–1.2659 mg/L, and the average EC50 value was

Discussion

Pydiflumetofen, a novel SDHI fungicide, exhibited strong inhibitory activity against the growth of mycelium and germination of conidium of B. cinerea. This study indicated that the inhibitory activity of pydiflumetofen on the germination of conidium was significantly higher than that on the growth of mycelium.

These results indicated that the sensitivities of B. cinerea to pydiflumetofen were similar in the 8 cities (Handan, Xingtai, Shijiazhuang, Baoding, Cangzhou, Hengshui, Qinhuangdao and

Authors' contribution statement

Jianjiang Zhao carried out the design of this study, samples collection and separation, implementation of this study, data acquisition, data and statistical analysis, and manuscript preparation; Xiuying Han and Wenqiao Wang participated in the design of this study, collection of samples, the implementation of field experiments and manuscript revision. Jie Wu, Fen Lu, Qiuyan Bi, and Kexin Yang carried out the separation of samples, data acquisition and analysis. All the authors have read and

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

No conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole

Acknowledgements

This study was supported by the Natural Science Foundation of Hebei Province, China (C2019301076), Key Research and Development Project of Hebei province, China (21326510D) andHAAFS Science and Technology Innovation Special Project, China (2019-1-1-4).

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