Sensitivity of Mycosphaerella pinodes to Pyraclostrobin Fungicide

Bowness, Robyne; Gossen, B. D.; Chang, K. F.; Goswani, Rubella; Willenborg, Christian J.; Holtz, Michael D.; Strelkov, Stephen E.

doi:10.1094/pdis-03-15-0350-re

Cited by 17 publications

(19 citation statements)

References 34 publications

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“…More frequent or heavier use of fungicides in an area may cause a greater shift in sensitivity relative to areas with less frequent use of the same product (Brent and Hollomon 2007). There are many sensitivity studies involving pyraclostrobin and other fungal pathogens in the Pleosporales (Gossen and Anderson 2004;Pasche et al 2004;Mondal et al 2005;Avenot et al 2008;Patel et al 2012;Vega et al 2012;Ahmed et al 2014;Vega and Dewdney 2014;Bowness et al 2016). However, due to natural variation in the fungicide sensitivity of species, different EC 50 values are to be expected (Vega and Dewdney 2014).…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of Leptosphaeria maculans to pyraclostrobin in Alberta, Canada

Fraser

Hwang²,

Ahmed³

et al. 2016

Can. J. Plant Sci.

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Strobilurin fungicides can be used to manage blackleg (Leptosphaeria maculans) of canola (Brassica napus); however, they have a high risk of selecting for resistance in fungal populations. In 2011, single-spore isolates of L. maculans were obtained from infected canola stubble representing six fields in Alberta, Canada. The isolates were grown on fungicide-amended agar plates and percent growth inhibition was calculated based on colony diameter relative to non-amended controls. Using probit regression analysis, the effective concentration of pyraclostrobin needed to inhibit mycelial growth by 50% (EC 50 ) was determined to be 0.09 mg L −1 based on 13 isolates. To identify highly insensitive isolates, 117 isolates were grown on agar plates amended with a discriminatory dose of 6.25 mg L −1 . Isolates in which growth was inhibited <50% were considered insensitive. Growth inhibition values ranged from 66.6% to 100.0% with a mean of 84.3%, indicating that all of the isolates were sensitive to pyraclostrobin. Forty-one of the 117 isolates were also tested via a microtiter plate assay. Based on conidial germination and subsequent growth, the EC 50 values obtained for each isolate ranged from 1.0 × 10 −4 to 7.4 × 10 −3 mg L −1 , which were not significantly different from those of the sensitive controls (4.1 × 10 −3 and 5.7 × 10 −3 mg L −1 ). While pyraclostrobin insensitivity was not detected in L. maculans populations from Alberta, continued monitoring will be necessary to track future changes.Key words: Leptosphaeria maculans, blackleg, Brassica napus, canola, pyraclostrobin, fungicide sensitivity.Résumé : Les fongicides à la strobilurine permettent de lutter contre la jambe noire (Leptosphaeria maculans) du canola (Brassica napus). Cependant, leur usage s'assortit d'un risque très élevé, car il pourrait concourir à la sélection de souches résistantes dans la population du cryptogame. En 2011, les auteurs ont recueilli des isolats d'une spore de L. maculans dans le chaume de canola infecté de six champs, en Alberta (Canada). Les isolats ont été cultivés sur des plaques de gélose enrichies de fongicide et on a calculé le degré d'inhibition de la croissance en pour cent d'après le diamètre des colonies, comparé à celui des colonies témoins poussant sur de la gélose non modifiée. L'analyse de régression par la méthode des probits a révélé que la concentration efficace de pyraclostrobine réduisant la croissance du mycélium de 50 % (CE 50 ) est de 0,09 mg par litre pour 13 isolats. Pour identifier les isolats les moins sensibles, les chercheurs en ont cultivé 117 sur des plaques de gélose enrichies avec une dose discriminatoire de 6,25 mg de fongicide par litre. Les isolats dont la croissance n'était pas réduite de plus de 50 % étaient considérés comme insensibles. L'inhibition de la croissance variait de 66,6 % à 100,0 %, avec une moyenne de 84,3 %, signe que tous les isolats étaient sensibles à la pyraclostrobine. Quarante-et-un des 117 isolats ont été testés dans le cadre d'un essai sur microplaque. D'après ...

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Section: Discussionmentioning

confidence: 99%

Sensitivity of Leptosphaeria maculans to pyraclostrobin in Alberta, Canada

Fraser

Hwang²,

Ahmed³

et al. 2016

Can. J. Plant Sci.

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“…The colony diameter was determined as the average of two perpendicular measurements after subtracting the diameter of the mycelial plug. The per cent inhibition was calculated relative to the control, and the medium effective concentration (EC 50 ) was calculated using log dose/probit regression line method (Bowness et al., 2016).…”

Section: Methodsmentioning

confidence: 99%

Effect of membrane integrity on survival competition of Botrytis cinerea upon QoI fungicide pyraclostrobin

Xiong

Fan

et al. 2020

Journal of Phytopathology

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Botrytis cinerea, the causal agent of the grey mould disease, developed resistance to multiple fungicides. However, the role of cell membrane in survival competition of B. cinerea upon quinone outside inhibitor (QoI) fungicide has not yet been elucidated. In this paper, the enhancement of cystamine, a transglutaminase inhibitor, on membrane integrity of B. cinerea was determined, and the effect of the enhancement on the sensitivity of B. cinerea to pyraclostrobin was investigated. The results showed that pyraclostrobin inhibited mycelial growth with EC50 as 1.122 and 3.042 μg/ml at 24 and 48 hr, respectively. In the treatment of 5 and 50 μg/ml pyraclostrobin, membrane integrity of B. cinerea was broken, causing high permeability, lipid peroxidation, flocculent and malformed surface with vague septum and abundant agglomerates inside and outside the mycelia. Cystamine even at 50 and 200 μg/ml had little inhibitory effect on mycelial growth. However, in presence of 50 or 200 μg/ml cystamine, the mycelia from pyraclostrobin treatment possessed a significantly reduced leakage, lower MDA content, and a revived fibrous and transparent surface. Meanwhile, SEM images showed that membrane integrity of the mycelia was significantly improved and the agglomerates were dramatically disappeared. Synergy assays further revealed that B. cinerea regained less sensitivity to pyraclostrobin inhibition. In conclusion, membrane integrity controls mycelia sensitivity and is required for survival competition of B. cinerea upon pyraclostrobin.

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“…Qualitative insensitivity predisposes the pathogen to become completely insensitive to the active ingredient and disease control is no longer achieved at recommended field application rates. Insensitivity to the QoI-fungicides has previously been reported to be qualitative ( Delgado et al, 2013 ; Bowness et al, 2016 ). QoI-resistant D. rabiei isolates have been identified in North Dakota and Montana ( Wise et al, 2008 , 2009 ), where the mechanism of resistance was identified as the G143A mutation in the former ( Delgado et al, 2013 ).…”

Section: Introductionmentioning

confidence: 94%

“…Prior to 2007, it was the only available fungicide MOA on pulse crops and resistance developed rapidly in North Dakota and Canada (Gossen and Anderson, 2004; Wise et al, 2011; Bowness et al, 2016). In 2012, SDHIs were registered for use and these have largely been released as blends with other fungicide MOAs due to the high risk of resistance development.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, of the three classes of fungicide, QoI fungicides are the choice of most pulse growers for pre- and post-infection management of AB in the United States and Canada ( Wise et al, 2008 ; Delgado et al, 2013 ; Lonergan et al, 2015 ; Bowness et al, 2016 ). Prior to 2007, it was the only available fungicide MOA on pulse crops and resistance developed rapidly in North Dakota and Canada ( Gossen and Anderson, 2004 ; Wise et al, 2011 ; Bowness et al, 2016 ). In 2012, SDHIs were registered for use and these have largely been released as blends with other fungicide MOAs due to the high risk of resistance development.…”

Section: Introductionmentioning

confidence: 99%

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The Detection and Characterization of QoI-Resistant Didymella rabiei Causing Ascochyta Blight of Chickpea in Montana

et al. 2017

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Ascochyta blight (AB) of pulse crops (chickpea, field pea, and lentils) causes yield loss in Montana, where 1.2 million acres was planted to pulses in 2016. Pyraclostrobin and azoxystrobin, quinone outside inhibitor (QoI) fungicides, have been the choice of farmers for the management of AB in pulses. However, a G143A mutation in the cytochrome b gene has been reported to confer resistance to QoI fungicides. A total of 990 isolates of AB-causing fungi were isolated and screened for QoI resistance. Out of these, 10% were isolated from chickpea, 81% were isolated from field peas, and 9% isolated from lentil. These were from a survey of grower’s fields and seed lots (chickpea = 17, field pea = 131, and lentil = 21) from 23 counties in Montana sent to the Regional Pulse Crop Diagnostic Laboratory, Bozeman, MT, United States for testing. Fungicide-resistant Didymella rabiei isolates were found in one chickpea seed lot each sent from Daniels, McCone and Valley Counties, MT, from seed produced in 2015 and 2016. Multiple alignment analysis of amino acid sequences showed a missense mutation that replaced the codon for amino acid 143 from GGT to GCT, introducing an amino acid change from glycine to alanine (G143A), which is reported to be associated with QoI resistance. Under greenhouse conditions, disease severity was significantly higher on pyraclostrobin-treated chickpea plants inoculated with QoI-resistant isolates of D. rabiei than sensitive isolates (p-value = 0.001). This indicates that where resistant isolates are located, fungicide failures may be observed in the field. D. rabiei-specific polymerase chain reaction primer sets and hydrolysis probes were developed to efficiently discriminate QoI- sensitive and - resistant isolates.

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Sensitivity of Mycosphaerella pinodes to Pyraclostrobin Fungicide

Cited by 17 publications

References 34 publications

Sensitivity of <i>Leptosphaeria maculans</i> to pyraclostrobin in Alberta, Canada

Sensitivity of <i>Leptosphaeria maculans</i> to pyraclostrobin in Alberta, Canada

Effect of membrane integrity on survival competition of Botrytis cinerea upon QoI fungicide pyraclostrobin

The Detection and Characterization of QoI-Resistant Didymella rabiei Causing Ascochyta Blight of Chickpea in Montana

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