Hormetic Effects of Thiophanate-Methyl in Multiple Isolates of <i>Sclerotinia homoeocarpa</i>

Pradhan, Sumit; Miller, Gerald L.; Marcillo, Vanessa; Koch, Alma; Grachet, Nathalia Graf; Molineros, Julio E.; Walker, Nathan; Melouk, H. A.; Garzón, Carla D.

doi:10.1094/pdis-05-18-0872-re

Cited by 8 publications

(3 citation statements)

References 41 publications

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“…Fungicide hormesis has profound implications for the application of fungicides. There have been numerous reports on fungicide hormesis, such as stimulatory effects of metalaxyl, mefenoxam, propamocarb, and cyazofamid on plant-pathogenic oomycetes Pythium aphanidermatum and Phytophthora infestans (Garzón et al 2011;Zhang et al 1997), and thiabendazole and thiophanate-methyl on fungal pathogens Penicillium expansum (Baraldi et al 2003) and Sclerotinia homoeocarpa (Pradhan et al 2019). In addition, our laboratory reported hormetic effects of carbendazim (Di et al 2015b), dimethachlone (Zhou et al 2014a), flusilazole (Lu et al 2018a, b), prochloraz (Zhang et al 2019), and trifloxystrobin (Di et al 2016a) on the pathogenicity of S. sclerotiorum.…”

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confidence: 99%

Stimulatory Effects of Boscalid on Virulence of Sclerotinia sclerotiorum Indicate Hormesis May Be Masked by Inhibitions

Zhang

et al. 2020

Plant Disease

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Hormetic effects of fungicides on phytopathogens are of great importance for proper application of fungicides. The aim of the present study was to investigate the stimulatory effects of the fungicide boscalid on mycelial growth and virulence of the devastating plant pathogen Sclerotinia sclerotiorum. Boscalid in potato dextrose agar (PDA) at a dosage range from 0.0005 to 0.002 μg/ml exerted statistically significant (P ≤ 0.015) stimulations on mycelial growth of S. sclerotiorum, and the maximum stimulation magnitudes were 5.55 ± 0.73% (mean ± SD) for the four isolates tested. Boscalid in PDA at 0.02 μg/ml inhibited mycelial growth of isolates HLJ3H and HLJ4H by 15.0 and 8.9%, respectively. However, after the growth-inhibited mycelia were inoculated on rapeseed leaves, isolates HLJ3H and HLJ4H exhibited virulence stimulations of 8.7 and 17.8%, respectively, indicating that hormesis may be masked by inhibitions. Boscalid sprayed at 0.0001 to 0.1 μg/ml on detached rapeseed leaves had significant (P ≤ 0.041) stimulations on virulence of S. sclerotiorum, and the maximum stimulation magnitudes were 17.90 ± 5.94% (mean ± SD) for the four isolates tested. Experiments on 12 isolates with different levels of virulence showed there was a negative correlation (R = –0.663, P = 0.019) between the maximum virulence stimulation magnitude and virulence of S. sclerotiorum in the absence of fungicide. Boscalid at stimulatory concentrations had no significant effect on the expression levels of three virulence-associated genes that encode cutinase (SsCut), polygalacturonase (SsPG1), and oxaloacetate acetylhydrolase (SsOah1). The molecular mechanisms for hormetic effects of boscalid on S. sclerotiorum remain to be studied in the future.

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Stimulatory Effects of Boscalid on Virulence of Sclerotinia sclerotiorum Indicate Hormesis May Be Masked by Inhibitions

Zhang

et al. 2020

Plant Disease

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“…This observation indicated that chlorothalonil and thiophanate-methyl might have in vitro hormetic effects on S. cuprophilus . Hormesis to fungicides (e.g., carbendazim, thiophanate-methyl) in some pathogenic fungi, such as Botrytis cinerea and Sclerotinia homoeocarpa , have recently been reported [ 47 , 48 ]. The effects may increase pathogen virulence under periods of sub-lethal fungicide exposure and result in increased disease incidence and severity [ 49 ].…”

Section: Discussionmentioning

confidence: 99%

Identification, Characterization, and Control of Black Spot on Chinese Kale Caused by Sphaerobolus cuprophilus sp. nov.

Kalayanamitra

Nontajak³

et al. 2023

Plants

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Chinese kale (Brassica alboglabra) is commonly grown and consumed throughout Asia and is often treated with chemicals to control pests and diseases. In Thailand, public standards, Good Agricultural Practice (GAP), and International Federation of Organic Agriculture Movement (IFOAM) programs were introduced for the cultivation of Chinese kale with minimum input of chemical treatments. Black spot caused by the fungus Sphaerobolus has been affecting the plants grown under IFOAM standards in Chiang Mai, Thailand, for several years. Strongly adhering glebal spore masses of the fungus on leaf and stem surfaces have adversely affected postharvest management, especially in the quality classification of the product. Both morphological and phylogenetic (combined ITS, mtSSU, and EF 1-α dataset) studies confirmed a novel species, S. cuprophilus. Pathogenicity tests involving inoculation of Chinese kale by non-wound and mulch inoculation bioassays resulted in the production of symptoms of black spot and the re-isolation of S. cuprophilus, indicating that the new fungal species is the causal agent of black spots. Inhibitory effects of antagonistic bacteria and chemical fungicides, both allowed for use in plant cultivation under either IFOAM or GAP standards, indicated that Bacillus amyloliquefaciens strains (PBT2 and YMB7), chlorothalonil (20 and 500 ppm) and thiophanate-methyl (500 and 1500 ppm) were the most effective in controlling the growth of the causal fungus by 83 to 93%. However, copper oxychloride (5 to 20 ppm), a recommended chemical in control of downy mildew of Chinese kale, showed hormetic effects on S. cuprophilus by promoting the growth and sporulation of the fungus. The findings of this study provide vital information regarding the association of S. cuprophilus and Chinese kale and will support decisions to manage fungal diseases of this vegetable.

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“…In S. sclerotiorum , pretreatment with flusilazole had hormetic effects for later exposure to flusilazole, prochloraz, tebuconazol [ 14 ]. The hormetic effects of pretreatment was also found in Sclerotinia homoeocarpa causing dollar spot disease in turf; when 28 isolates were cultured in corn meal agar containing 11 different concentrations of thiophanate-methyl, the mycelia growth of most preconditioned thiophanate-methyl isolates was significantly enhanced by 3–20% [ 34 ]. In this study, when the stimulated mycelia grown on carbendazim-amended PDA were inoculated on fungicide-free PDA, mycelia growth stimulations were still observed in the second-generation mycelia ( Table 2 ).…”

Section: Discussionmentioning

confidence: 99%

Hormetic Effects of Carbendazim on Mycelial Growth and Aggressiveness of Magnaporthe oryzae

Song

Han

Zhang

et al. 2022

JoF

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Rice blast caused by Magnaporthe oryzae is one of the most destructive fungal diseases of rice worldwide. Stimulatory effects of low doses of fungicides on pathogens are closely relevant to disease management. In the present study, in potato dextrose agar (PDA) amended with carbendazim at a dose range from 0.003 to 0.3 μg/mL, stimulatory effects on the mycelial growth of three isolates sensitive to carbendazim were tested. Carbendazim at concentrations from 0.003 to 0.1 µg/mL showed stimulatory effects on mycelial growth of isolates Guy11 and H08-1a, while carbendazim at concentrations from 0.003 to 0.03 µg/mL stimulated the growth of isolate P131. The maximum stimulation magnitudes were 11.84% for the three isolates tested. Mycelial colonies grown on PDA amended with different concentrations of carbendazim were incubated at 28 °C in darkness for 7 days as the pretreatment. Pretreatment mycelia were inoculated on fresh fungicide-free PDA and subsequent mycelia growth stimulations were still observed, and the maximum stimulation magnitudes were 9.15% for the three isolates tested. Pretreatment mycelia did not significantly change the tolerance to H2O2 and NaCl, except that the tolerance to H2O2 was increased significantly (p < 0.05) when the carbendazim was at 0.3 µg/mL. After five generations of mycelial transference on fungicide-free PDA, the transgenerational hormesis of mycelial were exhibited when transferred onto PDA supplemented with carbendazim at 0.3 µg/mL, and the maximum percent stimulation was 51.28%. The time course of infection indicated that the visible initial necrotic symptoms could be detected at 2 DPI on leaves treated with carbendazim at 0.03 µg/mL, whereas no necrotic symptom could be discerned for the control. Statistical results of lesion area and lesion type at 7 DPI showed that there was a significant stimulation (p < 0.05) on aggressiveness of M. oryzae isolate Guy11 on detached rice leaves at 0.03 µg/mL carbendazim. These results will advance our understanding of hormetic effects of fungicides and provide valuable information for judicious application of fungicides.

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Hormetic Effects of Thiophanate-Methyl in Multiple Isolates of Sclerotinia homoeocarpa

Cited by 8 publications

References 41 publications

Stimulatory Effects of Boscalid on Virulence of Sclerotinia sclerotiorum Indicate Hormesis May Be Masked by Inhibitions

Stimulatory Effects of Boscalid on Virulence of Sclerotinia sclerotiorum Indicate Hormesis May Be Masked by Inhibitions

Identification, Characterization, and Control of Black Spot on Chinese Kale Caused by Sphaerobolus cuprophilus sp. nov.

Hormetic Effects of Carbendazim on Mycelial Growth and Aggressiveness of Magnaporthe oryzae

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