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Anthony P. Keinath - One of the best experts on this subject based on the ideXlab platform.
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baseline sensitivity of didymella Bryoniae to cyprodinil and fludioxonil and field efficacy of these fungicides against isolates resistant to pyraclostrobin and boscalid
Plant Disease, 2015Co-Authors: Anthony P. KeinathAbstract:To prevent yield reductions from gummy stem blight, fungicides often must be applied to watermelon (Citrullus lanatus) and muskmelon (Cucumis melo). Didymella Bryoniae, the ascomycete fungus that causes gummy stem blight, is resistant to thiophanate-methyl, quinone-outside inhibitors (QoI), boscalid, and penthiopyrad. In place of these fungicides, premixtures of cyprodinil and fludioxonil (Switch 62.5WG) or cyprodinil and difenoconazole (Inspire Super 2.82SC) are used. The objectives of this study were to examine baseline isolates of D. Bryoniae for sensitivity to cyprodinil and fludioxonil and to determine the efficacy of cyprodinil-fludioxonil and cyprodinil-difenoconazole against isolates resistant to QoI fungicides and boscalid. Colony diameters of 146 isolates of D. Bryoniae collected in South Carolina and other U.S. states prior to 2008 were measured on glucose minimal medium amended with cyprodinil or fludioxonil. Mean effective concentration values that reduced relative colony diameter by 50% were...
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isolates of didymella Bryoniae from south carolina remain sensitive to dmi fungicides despite multiyear exposure
Journal of Phytopathology, 2013Co-Authors: Anthony P. Keinath, Zachariah R HansenAbstract:Triazole fungicides, which are sterol demethylation inhibitors, have become the primary systemic fungicides applied to cucurbits to control gummy stem blight caused by Didymella Bryoniae. Isolates of D. Bryoniae from South Carolina that were never exposed to tebuconazole or exposed for several years were tested for sensitivity to tebuconazole and difenoconazole. Colony diameters, percentage germination of ascospores and conidia, and germ tube lengths were measured when isolates were grown on agar amended with 0.10–10.0 mg/l tebuconazole and 0.01–1.0 mg/l difenoconazole. All 147 isolates tested were sensitive to tebuconazole and difenoconazole with mean EC50 values of 0.41 and 0.054 mg/l, respectively. Ascospore germination was greater than conidia germination on fungicide-amended agar. Although the length of germ tubes arising from both spore types was reduced by both fungicides, the reduction was greater for ascospore germ tubes than for conidia germ tubes. Because many watermelon growers rotate crops among fields every two years, local populations of D. Bryoniae have not been exposed repeatedly to tebuconazole. In addition, growers often apply a rotation of systemic and contact fungicides. Thus, despite exposure to tebuconazole for up to nine years, isolates of D. Bryoniae from South Carolina remain sensitive to triazole fungicides.
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from native plants in central europe to cultivated crops worldwide the emergence of didymella Bryoniae as a cucurbit pathogen
Hortscience, 2011Co-Authors: Anthony P. KeinathAbstract:Didvmella Bryoniae (Auersw.) Rehm lanamorph Phoma cucurbitacearum (Fr.) Sacc.], the plant pathogenic fungus that causes gummy stem blight and black rot on cucurbits, was first described in 1869 from Bryonia (bryony or wild hops) in central Europe. Today, this pathogen is found on six continents on at least 12 genera and 23 species of cucurbits. How did D. Bryoniae progress from a pathogen of a native plant in central Europe to a worldwide threat to cucurbits cultivated in humid environments? Clues from the early discoveries of this fungus, its characteristics as a seedborne pathogen, and its broad adaptation to cucurbit hosts will provide some answers to this question.
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sensitivity to azoxystrobin in didymella Bryoniae isolates collected before and after field use of strobilurin fungicides
Pest Management Science, 2009Co-Authors: Anthony P. KeinathAbstract:BACKGROUND: Isolates of Didymella Bryoniae (Auersw.) Rehm, causal agent of gummy stem blight on cucurbits, developed insensitivity to azoxystrobin in the eastern United States 2 years after first commercial use in 1998. Baseline sensitivity of this fungus to azoxystrobin has never been reported. The objectives were to compare baseline sensitivities of D. Bryoniae from South Carolina and other locations to sensitivities of isolates exposed to azoxystrobin for one or more seasons, and to compare sensitivity in vitro and in vivo. RESULTS: Sixty-one isolates of D. Bryoniae collected before 1998 were sensitive. Median EC50 was 0.055 mg L−1 azoxystrobin (range 0.005 to 0.81). Forty isolates collected after exposure during 1998 also were sensitive. Fifty-three of 64 isolates collected in South and North Carolina between 2000 and 2006 were insensitive to 10 mg L−1 azoxystrobin. Sensitive and insensitive isolates were distinguished by disease severity on Cucumis melo L. seedlings treated with azoxystrobin (20 or 200 mg L−1). CONCLUSIONS: An azoxystrobin baseline sensitivity distribution was established in vitro for isolates of D. Bryoniae never exposed to strobilurins. Baseline values were comparable with those of other ascomycetes. Insensitive isolates were found in fields with a history of strobilurin applications. An in vivo method distinguished sensitive and insensitive isolates. Copyright © 2009 Society of Chemical Industry
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survival of didymella Bryoniae in infested muskmelon crowns in south carolina
Plant Disease, 2008Co-Authors: Anthony P. KeinathAbstract:The crowns of muskmelon (Cucumis melo subsp. melo) plants are susceptible to cankers caused by the fungal pathogen Didymella Bryoniae. The objective of this study was to compare the length of time D. Bryoniae survived in infested crowns that were buried or left on the soil surface. Dried crowns with cankers were buried 12.5 cm deep, placed on the soil surface, or placed on top of raised beds covered with white-on-black polyethylene mulch from July 2002 to June 2003, December 2003 to October 2004, July 2004 to November 2005, and November 2005 to November 2007. At regular intervals, crowns or crown debris were retrieved, washed, cut into pieces, and cultured on semiselective medium to recover D. Bryoniae. D. Bryoniae was not recovered from crowns buried 35 and 45 weeks in 2003 and 2004 but was recovered from 2.5% of crowns buried 66 weeks in 2005. In contrast, D. Bryoniae was recovered after 48, 45, 66, and 103 weeks from 66, 6.3, 2.5, and 10% of crowns on the soil surface in 2003, 2004, 2005, and 2007, respectively. D. Bryoniae also was recovered after 66 and 103 weeks from 12.5 and 8% of crowns on mulched beds in 2005 and 2007. In two additional experiments, the pathogen was recovered from 15.0 and 20.1% of infested muskmelon debris left in place for 42 and 38 weeks on polyethylene-mulched beds. To reduce the time D. Bryoniae survives after a cucurbit crop, crop debris should be incorporated into soil promptly after harvest.
Mingguo Zhou - One of the best experts on this subject based on the ideXlab platform.
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Molecular and Biochemical Characterization of Pydiflumetofen-Resistant Mutants of Didymella Bryoniae.
Journal of agricultural and food chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was
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molecular and biochemical characterization of pydiflumetofen resistant mutants of didymella Bryoniae
Journal of Agricultural and Food Chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was <0.05 μg/mL. Eight pydiflumetofen-resistant mutants were obtained, and the level of resistance was stable. The mycelial growth, dry weight of mycelia, hyphal morphology, and pathogenicity of most resistant mutants did not change significantly compared with their parental strains, which indicated that the resistance risk of D. Bryoniae to pydiflumetofen would be medium to high. Sequencing alignment showed that five resistant mutants presented a mutation at codon 277 (H277Y) in the SdhB gene. The point mutants FgSdhBH248Y/R exhibited decreased sensitivity to pydiflumetofen in Fusarium graminearum, which indicated that the point mutants of SdhB could reduce sensitivity to pydiflumetofen. These results further increase our understanding about the mode of action and the resistance mechanism of pydiflumetofen.
Xuewei Mao - One of the best experts on this subject based on the ideXlab platform.
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Molecular and Biochemical Characterization of Pydiflumetofen-Resistant Mutants of Didymella Bryoniae.
Journal of agricultural and food chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was
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molecular and biochemical characterization of pydiflumetofen resistant mutants of didymella Bryoniae
Journal of Agricultural and Food Chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was <0.05 μg/mL. Eight pydiflumetofen-resistant mutants were obtained, and the level of resistance was stable. The mycelial growth, dry weight of mycelia, hyphal morphology, and pathogenicity of most resistant mutants did not change significantly compared with their parental strains, which indicated that the resistance risk of D. Bryoniae to pydiflumetofen would be medium to high. Sequencing alignment showed that five resistant mutants presented a mutation at codon 277 (H277Y) in the SdhB gene. The point mutants FgSdhBH248Y/R exhibited decreased sensitivity to pydiflumetofen in Fusarium graminearum, which indicated that the point mutants of SdhB could reduce sensitivity to pydiflumetofen. These results further increase our understanding about the mode of action and the resistance mechanism of pydiflumetofen.
Jianxin Wang - One of the best experts on this subject based on the ideXlab platform.
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Molecular and Biochemical Characterization of Pydiflumetofen-Resistant Mutants of Didymella Bryoniae.
Journal of agricultural and food chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was
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molecular and biochemical characterization of pydiflumetofen resistant mutants of didymella Bryoniae
Journal of Agricultural and Food Chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was <0.05 μg/mL. Eight pydiflumetofen-resistant mutants were obtained, and the level of resistance was stable. The mycelial growth, dry weight of mycelia, hyphal morphology, and pathogenicity of most resistant mutants did not change significantly compared with their parental strains, which indicated that the resistance risk of D. Bryoniae to pydiflumetofen would be medium to high. Sequencing alignment showed that five resistant mutants presented a mutation at codon 277 (H277Y) in the SdhB gene. The point mutants FgSdhBH248Y/R exhibited decreased sensitivity to pydiflumetofen in Fusarium graminearum, which indicated that the point mutants of SdhB could reduce sensitivity to pydiflumetofen. These results further increase our understanding about the mode of action and the resistance mechanism of pydiflumetofen.
Feifei Zhao - One of the best experts on this subject based on the ideXlab platform.
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Molecular and Biochemical Characterization of Pydiflumetofen-Resistant Mutants of Didymella Bryoniae.
Journal of agricultural and food chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was
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molecular and biochemical characterization of pydiflumetofen resistant mutants of didymella Bryoniae
Journal of Agricultural and Food Chemistry, 2020Co-Authors: Xuewei Mao, Jianxin Wang, Feifei Zhao, Jing Gao, Yiping Hou, Mingguo ZhouAbstract:Gummy stem blight (GSB), caused by Didymella Bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. Bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was <0.05 μg/mL. Eight pydiflumetofen-resistant mutants were obtained, and the level of resistance was stable. The mycelial growth, dry weight of mycelia, hyphal morphology, and pathogenicity of most resistant mutants did not change significantly compared with their parental strains, which indicated that the resistance risk of D. Bryoniae to pydiflumetofen would be medium to high. Sequencing alignment showed that five resistant mutants presented a mutation at codon 277 (H277Y) in the SdhB gene. The point mutants FgSdhBH248Y/R exhibited decreased sensitivity to pydiflumetofen in Fusarium graminearum, which indicated that the point mutants of SdhB could reduce sensitivity to pydiflumetofen. These results further increase our understanding about the mode of action and the resistance mechanism of pydiflumetofen.
