Impact of Fungicide Resistance in Plant Pathogens on Crop Disease Control and Agricultural Environment

2006 ◽  
Vol 40 (3) ◽  
pp. 205-211 ◽  
Author(s):  
Hideo ISHII
Keyword(s):  
Disease Control ◽  
Fungicide Resistance ◽  
Plant Pathogens ◽  
Agricultural Environment ◽  
Crop Disease

scholarly journals Fungicide Resistance Evolving in Ramularia Collo-Cygni Population in Estonia

2021 ◽  
Vol 9 (7) ◽  
pp. 1514
Author(s):  
Riinu Kiiker ◽  
Marite Juurik ◽  
Andres Mäe
Keyword(s):  
Disease Control ◽  
High Resistance ◽  
Fungicide Resistance ◽  
Spring Barley ◽  
Point Mutations ◽  
Ramularia Leaf Spot ◽  
Entire Collection ◽  
Dmi Fungicides ◽  
Fungicide Target ◽  
Succinate Dehydrogenase Inhibitors

Ramularia leaf spot caused by the fungus Ramularia collo-cygni, has recently become widespread in Estonian barley fields. Currently, disease control in barley fields relies on SDHI and DMI fungicides, which might be threatened by R. collo-cygni isolates that are well-adapted to fungicide pressure. In a two-year study, 353 R. collo-cygni isolates were collected from spring barley fields in Estonia. A total of 153 R. collo-cygni isolates were examined for sensitivity to azoles (DMIs; prothioconazole-desthio, epoxiconazole, mefentrifluconazole) and succinate dehydrogenase inhibitors (SDHIs; boscalid, fluxapyroxad). Epoxiconazole was the least effective and a new fungicide mefentrifluconazole was the most effective DMI. Among SDHIs, fluxapyroxad was more effective than boscalid. Also, single R. collo-cygni isolates with high resistance to tested fungicides occurred, which could affect fungicide control of the pathogen. The entire collection of R. collo-cygni was analysed for mutations in fungicide target proteins. Six mutations were identified in CYP51 gene, the most dominant being I381T, I384T, and S459C. Also, numerous point mutations in the SdhC gene were present. The mutation G143A in strobilurin target protein CytB dominates in over 80% of the R. collo-cygni population, confirming the low efficacy of strobilurin fungicides in barley disease control.

scholarly journals When time really is money: in situ quantification of the strobilurin resistance mutation G143A in the wheat pathogen Blumeria graminis f. sp. tritici

2020 ◽  
Author(s):  
Kejal N Dodhia ◽  
Belinda A Cox ◽  
Richard P Oliver ◽  
Francisco J Lopez-Ruiz
Keyword(s):  
Fungicide Resistance ◽  
Plant Pathogens ◽  
Resistance Mutation ◽  
Digital Pcr ◽  
Blumeria Graminis ◽  
Diagnostic Methods ◽  
Sample Collection ◽  
Specific Pcr ◽  
Field Samples

AbstractBackgroundThere has been an inexorable increase in the incidence of fungicide resistance in plant pathogens in recent years. Control of diseases and the management of resistance would be greatly aided by rapid diagnostic methods. Quantitative allele specific PCR (ASqPCR) is an ideal technique for the analysis of fungicide resistance in the field as it can both detect and quantify the frequency of mutations associated with fungicide resistance. We have applied this technique to the fungal pathogen Blumeria graminis f. sp. tritici (Bgt), an obligate biotrophic fungus that causes wheat powdery mildew and is responsible for up to 25% yield loss annually. In Australia, strobilurin resistant Bgt was first discovered in samples from Tasmania and Victoria in 2016. Molecular analysis revealed a nucleotide transversion in the cytochrome bc1 enzyme (cytb) complex, resulting in a substitution of alanine for glycine at position 143 (G143A) in Cytb.ResultsWe have developed an in-field ASqPCR assay that can quantify both the resistant (A143) and sensitive (G143) cytb alleles down to 1.67% in host and Bgt DNA mixtures within 90 min of sample collection. The in situ analysis of field samples collected during a survey in Tasmania revealed A143 frequencies ranging between 9-100%. We validated the analysis with a newly developed laboratory based digital PCR assay and found no significant differences between the two methods.ConclusionWe have successfully developed an in-field quantification method, for a QoI resistant allele, by pairing an ASqPCR assay on a lightweight qPCR instrument with a quick DNA extraction method. The deployment of this type of methodologies in the field can contribute to the effective in-season management of fungicide resistance.

scholarly journals Mixtures as a Fungicide Resistance Management Tactic

2014 ◽  
Vol 104 (12) ◽  
pp. 1264-1273 ◽  
Author(s):  
Frank van den Bosch ◽  
Neil Paveley ◽  
Femke van den Berg ◽  
Peter Hobbelen ◽  
Richard Oliver
Keyword(s):  
At Risk ◽  
Disease Control ◽  
Fungicide Resistance ◽  
Management Strategies ◽  
Resistance Management ◽  
Relative Effect ◽  
Resistance Evolution ◽  
Modes Of Action ◽  
Selection For ◽  
Effective Life

We have reviewed the experimental and modeling evidence on the use of mixtures of fungicides of differing modes of action as a resistance management tactic. The evidence supports the following conclusions. 1. Adding a mixing partner to a fungicide that is at-risk of resistance (without lowering the dose of the at-risk fungicide) reduces the rate of selection for fungicide resistance. This holds for the use of mixing partner fungicides that have either multi-site or single-site modes of action. The resulting predicted increase in the effective life of the at-risk fungicide can be large enough to be of practical relevance. The more effective the mixing partner (due to inherent activity and/or dose), the larger the reduction in selection and the larger the increase in effective life of the at-risk fungicide. 2. Adding a mixing partner while lowering the dose of the at-risk fungicide reduces the selection for fungicide resistance, without compromising effective disease control. The very few studies existing suggest that the reduction in selection is more sensitive to lowering the dose of the at-risk fungicide than to increasing the dose of the mixing partner. 3. Although there are very few studies, the existing evidence suggests that mixing two at-risk fungicides is also a useful resistance management tactic. The aspects that have received too little attention to draw generic conclusions about the effectiveness of fungicide mixtures as resistance management strategies are as follows: (i) the relative effect of the dose of the two mixing partners on selection for fungicide resistance, (ii) the effect of mixing on the effective life of a fungicide (the time from introduction of the fungicide mode of action to the time point where the fungicide can no longer maintain effective disease control), (iii) polygenically determined resistance, (iv) mixtures of two at-risk fungicides, (v) the emergence phase of resistance evolution and the effects of mixtures during this phase, and (vi) monocyclic diseases and nonfoliar diseases. The lack of studies on these aspects of mixture use of fungicides should be a warning against overinterpreting the findings in this review.

scholarly journals Detection and monitoring of fungicide resistance in plant pathogens using pyrosequencing

2016 ◽  
Vol 41 (1) ◽  
pp. 78-87 ◽  
Author(s):  
Makoto Fujimura ◽  
Shinpei Banno ◽  
Masayuki Kamei ◽  
Yohei Ishigami ◽  
Yoshihito Tsukada
Keyword(s):  
Fungicide Resistance ◽  
Plant Pathogens

scholarly journals Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?

2014 ◽  
Vol 104 (4) ◽  
pp. 324-331 ◽  
Author(s):  
Alexey Mikaberidze ◽  
Bruce A. McDonald ◽  
Sebastian Bonhoeffer
Keyword(s):  
High Risk ◽  
Disease Control ◽  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Development Of Resistance ◽  
Population Dynamics Model ◽  
Fungicide Mixtures ◽  
Cost Of Resistance ◽  
Selection For ◽  
Crucial Parameter

Fungicide mixtures produced by the agrochemical industry often contain low-risk fungicides, to which fungal pathogens are fully sensitive, together with high-risk fungicides known to be prone to fungicide resistance. Can these mixtures provide adequate disease control while minimizing the risk for the development of resistance? We present a population dynamics model to address this question. We found that the fitness cost of resistance is a crucial parameter to determine the outcome of competition between the sensitive and resistant pathogen strains and to assess the usefulness of a mixture. If fitness costs are absent, then the use of the high-risk fungicide in a mixture selects for resistance and the fungicide eventually becomes nonfunctional. If there is a cost of resistance, then an optimal ratio of fungicides in the mixture can be found, at which selection for resistance is expected to vanish and the level of disease control can be optimized.

scholarly journals Using Epidemiological Principles to Explain Fungicide Resistance Management Tactics: Why do Mixtures Outperform Alternations?

2018 ◽  
Vol 108 (7) ◽  
pp. 803-817 ◽  
Author(s):  
James A. D. Elderfield ◽  
Francisco J. Lopez-Ruiz ◽  
Frank van den Bosch ◽  
Nik J. Cunniffe
Keyword(s):  
High Risk ◽  
Disease Control ◽  
Fungicide Resistance ◽  
Total Yield ◽  
Resistance Management ◽  
Careful Consideration ◽  
Low Risk ◽  
Model Parameterization ◽  
Grapevine Powdery Mildew ◽  
Label Dose

Whether fungicide resistance management is optimized by spraying chemicals with different modes of action as a mixture (i.e., simultaneously) or in alternation (i.e., sequentially) has been studied by experimenters and modelers for decades. However, results have been inconclusive. We use previously parameterized and validated mathematical models of wheat Septoria leaf blotch and grapevine powdery mildew to test which tactic provides better resistance management, using the total yield before resistance causes disease control to become economically ineffective (“lifetime yield”) to measure effectiveness. We focus on tactics involving the combination of a low-risk and a high-risk fungicide, and the case in which resistance to the high-risk chemical is complete (i.e., in which there is no partial resistance). Lifetime yield is then optimized by spraying as much low-risk fungicide as is permitted, combined with slightly more high-risk fungicide than needed for acceptable initial disease control, applying these fungicides as a mixture. That mixture rather than alternation gives better performance is invariant to model parameterization and structure, as well as the pathosystem in question. However, if comparison focuses on other metrics, e.g., lifetime yield at full label dose, either mixture or alternation can be optimal. Our work shows how epidemiological principles can explain the evolution of fungicide resistance, and also highlights a theoretical framework to address the question of whether mixture or alternation provides better resistance management. It also demonstrates that precisely how spray tactics are compared must be given careful consideration.[Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

scholarly journals Evidence of Selection for Fungicide Resistance in Zymoseptoria tritici Populations on Wheat in Western Oregon

Plant Disease ◽  
2016 ◽  
Vol 100 (2) ◽  
pp. 483-489 ◽  
Author(s):  
Laura E. Hayes ◽  
Kathryn E. Sackett ◽  
Nicole P. Anderson ◽  
Michael D. Flowers ◽  
Christopher C. Mundt
Keyword(s):  
Fungicide Resistance ◽  
Fungal Pathogen ◽  
Plant Pathogens ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Resistance Evolution ◽  
Regional Control ◽  
Selection For ◽  
Moderately Resistant

Plant pathogens pose a major challenge to maintaining food security in many parts of the world. Where major plant pathogens are fungal, fungicide resistance can often thwart regional control efforts. Zymoseptoria tritici, causal agent of Septoria tritici blotch, is a major fungal pathogen of wheat that has evolved resistance to chemical control products in four fungicide classes in Europe. Compared with Europe, however, fungicide use has been less and studies of fungicide resistance have been infrequent in North American Z. tritici populations. Here, we confirm first reports of Z. tritici fungicide resistance evolution in western Oregon through analysis of the effects of spray applications of propiconazole and an azoxystrobin + propiconazole mixture during a single growing season. Frequencies of strobilurin-resistant isolates, quantified as proportions of G143A mutants, were significantly higher in azoxystrobin-sprayed plots compared with plots with no azoxystrobin treatment at two different locations and were significantly higher in plots of a moderately resistant cultivar than in plots of a susceptible cultivar. Thus, it appears that western Oregon Z. tritici populations have the potential to evolve levels of strobilurin resistance similar to those observed in Europe. Although the concentration of propiconazole required to reduce pathogen growth by 50% values were numerically greater for isolates collected from plots receiving propiconazole than in control plots, this effect was not significant (P > 0.05).

scholarly journals At Least Two Origins of Fungicide Resistance in Grapevine Downy Mildew Populations

2007 ◽  
Vol 73 (16) ◽  
pp. 5162-5172 ◽  
Author(s):  
Wei-Jen Chen ◽  
François Delmotte ◽  
Sylvie Richard Cervera ◽  
Lisette Douence ◽  
Charles Greif ◽  
...  
Keyword(s):  
Plant Pathogen ◽  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Plasmopara Viticola ◽  
Isolated Populations ◽  
Grapevine Downy Mildew ◽  
First Case ◽  
Wide Range ◽  
Pathogen Populations

ABSTRACT Quinone outside inhibiting (QoI) fungicides represent one of the most widely used groups of fungicides used to control agriculturally important fungal pathogens. They inhibit the cytochrome bc 1 complex of mitochondrial respiration. Soon after their introduction onto the market in 1996, QoI fungicide-resistant isolates were detected in field plant pathogen populations of a large range of species. However, there is still little understanding of the processes driving the development of QoI fungicide resistance in plant pathogens. In particular, it is unknown whether fungicide resistance occurs independently in isolated populations or if it appears once and then spreads globally by migration. Here, we provide the first case study of the evolutionary processes that lead to the emergence of QoI fungicide resistance in the plant pathogen Plasmopara viticola. Sequence analysis of the complete cytochrome b gene showed that all resistant isolates carried a mutation resulting in the replacement of glycine by alanine at codon 143 (G143A). Phylogenetic analysis of a large mitochondrial DNA fragment including the cytochrome b gene (2,281 bp) across a wide range of European P. viticola isolates allowed the detection of four major haplotypes belonging to two distinct clades, each of which contains a different QoI fungicide resistance allele. This is the first demonstration that a selected substitution conferring resistance to a fungicide has occurred several times in a plant-pathogen system. Finally, a high population structure was found when the frequency of QoI fungicide resistance haplotypes was assessed in 17 French vineyards, indicating that pathogen populations might be under strong directional selection for local adaptation to fungicide pressure.

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