Protective and curative efficacy of prothioconazole against isolates of <i>Mycosphaerella graminicola</i> differing in their <i>in vitro</i> sensitivity to DMI fungicides

Sanssené, Jean; Selim, Sameh; Roisin-Fichter, Céline; Djerroud, L.; Deweer, Caroline; Halama, Patrice

doi:10.1002/ps.2163

Cited by 13 publications

(10 citation statements)

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“…Previous research has shown that reduced rates of the DMI fungicide flutriafol exhibited reduced efficacy to control CLS compared with the full recommended rate (24). In contrast, a recent experiment on the effect of prothioconazole rate on disease caused by M. graminicola showed that application rate had no differential effect on disease-causing ability of three high EC50 value isolates (37). The finding that the high EC50 value isolate caused significantly more disease than the medium or low EC50 value isolates at the field rate suggests that the EC50 value of 1.0 |jg ml"' is a valid threshold above which isolates may be considered DMI resistant.…”

Section: Discussionmentioning

confidence: 81%

“…DMIs have gained popularity due to protective and curative properties and low levels of phytotoxicity (10,37). DMI-resistant isolates initially were thought to cause less disease than DMIsensitive isolates, suggesting that DMI resistance would not become widespread in field populations (11,13).…”

mentioning

confidence: 99%

“…Fungicide sensitivity of field isolates can be measured by calculating 50% effective concentration (EC50) values (14,25,26,30,(37)(38)(39)43). The EC50 value is the concentration of fungicide in media that reduces fungal growth or spore germination by 50% compared with growth on nonamended media (38).…”

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confidence: 99%

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Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

et al. 2012

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Bolton, M. D., Rivera-Varas, V., del Rio Mendoza, L. E., Khan, M. F. R., and Secor, G. A. 2012. Efficacy of variable tetraconazole rates against Cercospora beticola isolates with differing in vitro sensitivities to DMI fungicides. Plant Dis. 96:1749-1756.Cercospora leaf spot (CLS) of sugar beet is caused by the fungus Cercospora beticola. CLS management practices include the application of the sterol demethylation inhibitor (DMI) fungicides tetraconazole, difenoconazole, and prothioconazole. Evaluating resistance to DMIs is a major focus for CLS fungicide resistance management. Isolates were collected in 1997 and 1998 (baseline sensitivity to tetraconazole, prothioconazole, or difenoconazole) and 2007 through 2010 from the major sugar-beet-growing regions of Minnesota and North Dakota and assessed for in vitro sensitivity to two or three DMI fungicides. Most (47%) isolates collected in 1997-98 exhibited 50% effective concentration (EC50) values for tetraconazole of <0.01 (Jg ml"', whereas no isolates could be found in this EC50 range in 2010. Since 2007, annual median and mean tetraconazole EC50 values have generally been increasing, and the frequency of isolates with EC50 values >0.11 lig ml-' increased from 2008 to 2010. In contrast, the frequency of isolates with EC50 values for prothioconazole of >1.0 ng mh' has been decreasing since 2007. Annual median difenoconazole EC50 values appears to be stable, although annual mean EC50 values generally have been increasing for this fungicide. Although EC50 values are important for gauging fungicide sensitivity trends, a rigorous comparison of the relationship between in vitro EC50 values and loss of fungicide efficacy in planta has not been conducted for C. beticola. To explore this, 12 isolates exhibiting a wide range of tetraconazole EC50 values were inoculated to sugar beet but no tetraconazole was applied. No relationship was found between isolate EC50 value and disease severity. To assess whether EC50 values are related to fungicide efficacy in planta, sugar beet plants were sprayed with various dilutions of Eminent, the commercial formulation of tetraconazole, and subsequently inoculated with isolates that exhibited very low, medium, or high tetraconazole EC50 values. The high EC50 isolate caused significantly more disease than isolates with medium or very low EC50 values at the field application rate and most reduced rates. Because in vitro sensitivity testing is typically carried out with the active ingredient of the commercial fungicide, we investigated whether loss of disease control was the same for tetraconazole as for the commercial product Eminent. The high EC50 isolate caused more disease on plants treated with tetraconazole than Eminent but disease severity was not different between plants inoculated with the very low EC50 isolate.Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola (Sacc), is the most important foliar disease of sugar beet {Beta vulgaris L.) in North Dakota and Minnesota (39). The disease causes a reduction in root har...

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Section: Discussionmentioning

confidence: 81%

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confidence: 99%

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Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

et al. 2012

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“…To date, application of fungicides, mainly the sterol 14α-demethylase inhibitors (DMIs), remained as the main method for controlling this disease (Gouache et al, 2009;Sanssené et al, 2011;Somai-Jemmali et al, 2014). However, a high proportion of DMI-moderate resistant genotypes (≥94%) was recently recorded Selim, 2009;.…”

Section: Introductionmentioning

confidence: 99%

Biological control of septoria leaf blotch and growth promotion in wheat by Paenibacillus sp. strain B2 and Curtobacterium plantarum strain EDS

Samain¹,

Tuinen

Jeandet

et al. 2017

Biological Control

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Keywords:Wheat septoria leaf blotch Paenimyxin Paenibacillus sp. strain B2 Curtobacterium plantarum Flavonoids Salicylic acid Jasmonic acid Reactive oxygen species A B S T R A C T Many of the non-pathogenic endophytic bacteria that reside in plant roots promote plant growth as well as protection against pathogens attack. However, little is known about their mode of action in wheat. We have previously demonstrated the potential of Paenibacillus sp. strain B2 (PB2) to stimulate plant defense mechanisms via its paenimyxin lipo-polypeptide elicitor. Recently, we isolated the Curtobacterium plantarum strain EDS (EDS) from seeds of almost all wheat cultivars. In the present work, the ability of PB2 and EDS to promote wheat growth and protection against Septoria leaf blotch (SLB) was investigated. Results showed that PB2 is a general root external colonizer and cultivar-dependent endophyte. In the endophytic state and only in co-inoculation, it significantly increased the internal root colonization by EDS, resulting in an increase of root and aerial part fresh weights. qPCR analysis showed that, in the endophytic and nonendophytic states, PB2 conferred ≥59% protection against SLB by inducing systemic resistance which is characterized by the over expression of the pr1, lox, Aos, peroxidase, oxo and gst genes. Paenimyxin conferred 76% local protection characterized by the overexpression of the glu, lox, aos, pal, chs, oxo, and gst genes, and 82% systemic protection by chs. It was concluded that PB2 is potentially very interesting in the biocontrol of SLB and, in a mixture with EDS, in the wheat growth promoting. Genes involved in the flavonoid, salicylic acid, jasmonic acid, reactive oxygen species and basal defense pathways seem to play an important role in the resistance against SLB.

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“…The fungicide prothioconazole was introduced to the European market in 2002 and is widely used to control M. graminicola and other pathogens in cereals (Dutzmann, Suty-Heinze, 2004;Sanssene et al, 2011). Prothioconazole has been sold in commercial mixtures with tebuconazole (Prosaro) and spiroxamine (Input) in Lithuania since 2006.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of Mycosphaerella graminicola isolates to demethylation-inhibiting (DMI) fungicides

Ronis

Jørgensen

Semaškienė

et al. 2014

Zemdirbyste-Agriculture

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Mycosphaerella graminicola (Fuckel) J. Schröt. (anamorph Zymoseptoria tritici (Desm.) Quaedvlieg & Crous) causes Septoria leaf blotch disease of wheat. The disease can be responsible for yield losses of 30-50% and, when severe, requires management with a fungicide. Single picnidia isolates collected from different locations of Lithuania were tested in vitro for sensitivity to demethylation-inhibiting (DMI) fungicides epoxiconazole, cyproconazole and prothioconazole. Fungicide concentrations were chosen from the proposed Fungicide Resistance Action Committee (FRAC) methods. Microtitre plates with 96-wells were inoculated with suspensions of pycnidiospores taken from single pycnidia of leaves. In total, 196 isolates from 34 locations were tested over the three experimental years (2009)(2010)(2011). The results showed reduced sensitivity of M. graminicola isolates to epoxiconazole and cyproconazole. The average EC 50 values over three experimental years for epoxiconazole varied between 1.02 and 3.15 mg l -1 , for cyproconazole -1.51 and 10.66 mg l -1 . The sensitivity to prothioconazole of 64 isolates from 13 locations (2011) ranged from 0.43 to 32.28 mg l -1 . Results of field experiments (2007)(2008)(2009)(2010)(2011) showed that fungicides epoxiconazole and prothioconazole significantly reduced the area under the disease progress curve (AUDPC) values of Septoria leaf blotch compared with untreated plots in winter wheat. In most cases, a single fungicide application significantly increased grain yield and a thousand grain weight weight.

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Protective and curative efficacy of prothioconazole against isolates of Mycosphaerella graminicola differing in their in vitro sensitivity to DMI fungicides

Abstract: A protective application of prothioconazole in wheat crops could be the best strategy to keep a high efficacy against Septoria leaf blotch.

Cited by 13 publications

References 15 publications

Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

Biological control of septoria leaf blotch and growth promotion in wheat by Paenibacillus sp. strain B2 and Curtobacterium plantarum strain EDS

Sensitivity of Mycosphaerella graminicola isolates to demethylation-inhibiting (DMI) fungicides

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