scholarly journals Adaptation to Fungicides in Monilinia fructicola Isolates with Different Fungicide Resistance Phenotypes

2008 ◽  
Vol 98 (2) ◽  
pp. 230-238 ◽  
Author(s):  
Chao-Xi Luo ◽  
Guido Schnabel
Keyword(s):  
Fungicide Resistance ◽  
Monilinia Fructicola ◽  
Uv Mutagenesis ◽  
Resistance Development ◽  
Quinone Outside Inhibitor ◽  
Induced Mutants ◽  
Dmi Fungicides ◽  
Selection Medium ◽  
Parental Isolate ◽  
Higher Doses

The ability to develop fungicide resistance was assessed in Monilinia fructicola isolates with different fungicide sensitivity phenotypes by adapting mycelium and conidia to increasing concentrations of selective fungicides and UV mutagenesis. Results showed that adaptation to Quinone outside inhibitor (QoI) fungicide azoxystrobin and sterol demethylation inhibitor (DMI) fungicide propiconazole was more effective in conidial-transfer experiments compared to mycelial-transfer experiments. DMI-resistant (DMI-R) isolates adapted to significantly higher doses of azoxystrobin in both, mycelial- and conidial-transfer experiments compared to benzimidazole-resistant (BZI-R) and sensitive (S) isolates. Adaptation to propiconazole in conidial-transfer experiments was accelerated in BZI-R isolates when a stable, nonlethal dose of 50 μg/ml thiophanate-methyl was added to the selection medium. One of two azoxystrobin-resistant mutants from DMI-R isolates did not show any fitness penalties; the other isolate expired before further tests could be carried out. The viable mutant caused larger lesions on detached peach fruit sprayed with azoxystrobin compared to the parental isolate. The azoxystrobin sensitivity of the viable mutant returned to baseline levels after the mutant was transferred to unamended medium. However, azoxystrobin resistance recovered quicker in the mutant compared to the corresponding parental isolate after renewed subculturing on medium amended with 0.2 and 1 μg/ml azoxystrobin; only the mutant but not the parental isolate was able to adapt to 5 μg/ml azoxystrobin. In UV mutagenesis experiments, the DMI-R isolates produced significantly more mutants compared to S isolates. All of the UV-induced mutants showed stable fungicide resistance with little fitness penalty. This study indicates the potential for QoI fungicide resistance development in M. fructicola in the absence of a mutagen and provides evidence for increased mutability and predisposition to accelerated adaptation to azoxystrobin in M. fructicola isolates resistant to DMI fungicides.

scholarly journals Tank Mixing Fungicides for Effectiveness Against Eastern Filbert Blight of Hazelnut

Plant Disease ◽  
2018 ◽  
Vol 102 (5) ◽  
pp. 919-924 ◽  
Author(s):  
J. W. Pscheidt ◽  
S. Heckert ◽  
S. A. Cluskey
Keyword(s):  
Corylus Avellana ◽  
Resistance Development ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Action Committee ◽  
Anisogramma Anomala ◽  
Dmi Fungicides ◽  
Group 3 ◽  
Eastern Filbert Blight ◽  
Control Tank

Hazelnut (Corylus avellana) production in Oregon primarily occurs on cultivars susceptible to Anisogramma anomala, the causal agent of eastern filbert blight (EFB). Management of EFB involves planting resistant cultivars, removal of cankered limbs, and the application of fungicides. Tank mixes of demethylation-inhibiting (DMI; Fungicide Resistance Action Committee [FRAC] group 3) or quinone outside inhibitor (QoI; FRAC group 11) fungicides with chlorothalonil (FRAC group M5) at full or reduced rates were evaluated for effectiveness against A. anomala. The use of chlorothalonil in a mix with a DMI or QoI fungicide was an effective treatment for EFB even if each component of the mix was at half the labeled rate. Different liquid or dry formulations of chlorothalonil were equally effective in a tank mix for EFB control. The combination of propiconazole (FRAC group 3) tank mixed with trifloxystrobin (FRAC group 11) was not effective, whereas trees treated with propiconazole tank mixed with pyraclostrobin (FRAC group 11) resulted in significantly fewer EFB cankers compared with nontreated trees. When using tank mixes for EFB management, DMI fungicides should remain at full rates while mixing with a half-rate of chlorothalonil. In contrast, QoI fungicides and chlorothalonil could both be used at half-rates and still maintain acceptable EFB control. Tank mixing chlorothalonil with fungicides at risk of resistance development can help maintain consistent EFB control and should help prevent or delay the emergence of fungicide-resistant A. anomala isolates.

scholarly journals Investigating the sensitivity of Venturia inaequalis isolates to difenoconazole and pyraclostrobin in apple orchards in China

2021 ◽  
Author(s):  
Xiancheng Li ◽  
Haiyuan Li ◽  
Zhen Yu ◽  
Liqiang Gao ◽  
Jiarong Yang
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Weak Correlation ◽  
Resistance Level ◽  
Resistance Development ◽  
Autonomous Region ◽  
Quinone Outside Inhibitor ◽  
Xinjiang Autonomous Region ◽  
Single Lesion ◽  
Demethylation Inhibitor

AbstractThe resistance level of 90 single lesion conidial isolates of Venturia inaequalis collected from multiple commercial orchards in Shaanxi and Gansu Provinces and Xinjiang Autonomous Region of China to the demethylation inhibitor (DMI) fungicide difenoconazole and quinone outside inhibitor (QoI) fungicide pyraclostrobin was examined. The EC50 values of the 90 isolates to difenoconazole and pyraclostrobin ranged from 0.143 to 6.735 μg/mL and 0.084 to 2.026 μg/mL, respectively. Among the isolates, 19 had resistance, 66 had reduced sensitivity, and five had sensitivity to difenoconazole; eight had resistance, 81 had reduced sensitivity, and one had sensitivity to pyraclostrobin. Although a weak correlation between difenoconazole and pyraclostrobin was detected, four isolates were identified as resistant to difenoconazole and pyraclostrobin. However, isolates with practical resistance were not found widely in our study and were only sporadic in a few places, indicating that at present, difenoconazole and pyraclostrobin are still safe for disease management in the apple-growing areas of Shaanxi, Gansu and Xinjiang. However, the risk of fungicide resistance should be managed with caution, and yearly monitoring of resistance development is necessary.

scholarly journals Lack of an intron in cytochrome b and overexpression of sterol 14α-demethylase indicate a potential risk for QoI and DMI resistance development in Neophysopella spp. on grapes

2021 ◽  
Author(s):  
Ricardo Feliciano Santos ◽  
Lilian Amorim ◽  
Ana K.M. Wood ◽  
Líllian Beatriz Bibiano ◽  
Bart Fraaije
Keyword(s):  
Cytochrome B ◽  
Potential Risk ◽  
Leaf Disc ◽  
Fold Increase ◽  
Resistance Mechanisms ◽  
Resistance Development ◽  
Quinone Outside Inhibitor ◽  
Dmi Fungicides ◽  
The Mean ◽  
Dmi Resistance

Asian grapevine leaf rust, caused by Neophysopella meliosmae-myrianthae and N. tropicalis, is often controlled by quinone outside inhibitor (QoI) and demethylation inhibitor (DMI) fungicides in Brazil. Here, we evaluated the sensitivity of 55 Neophysopella spp. isolates to pyraclostrobin (QoI) and tebuconazole (DMI). To elucidate the resistance mechanisms, we analyzed the sequences of the cytochrome b (CYTB) and cytochrome P450 sterol 14α-demethylase (CYP51) target proteins of QoI and DMI fungicides, respectively. The CYP51 expression levels were also determined in a selection of isolates. In leaf disc assays, the mean 50% effective concentration (EC50) value for pyraclostrobin was around 0.040 µg/ml for both species. CYTB sequences were identical among all 55 isolates, which did not contain an intron immediately after codon 143. No amino acid substitution was identified at codons 129, 137 and 143. The mean EC50 value for tebuconazole was 0.62 µg/ml for N. tropicalis and 0.46 µg/ml for N. meliosmae-myrianthae and no CYP51 sequence variation was identified among isolates of the same species. However, five N. meliosmae-myrianthae isolates grew on leaf discs treated at 10 µg/ml tebuconazole and these were further exposed to tebuconazole selection pressure. Tebuconazole-adapted laboratory isolates of N. meliosmae-myrianthae showed an eight- to 25-fold increase in resistance after four rounds of selection that was not associated with CYP51 target alterations. In comparison with sensitive isolates, CYP51 expression was induced in the presence of tebuconazole in three out of four tebuconazole-adapted isolates tested. These results suggest a potential risk for QoI and DMI resistance development in Neophysopella spp.

scholarly journals Sensitivity of grapevine powdery mildew (Erysiphe necator) to demethylation inhibitor and quinone outside inhibitor fungicides in New Zealand

2016 ◽  
Vol 69 ◽  
pp. 1-10 ◽  
Author(s):  
R.M. Beresford ◽  
P.J. Wright ◽  
P.N. Wood ◽  
R.H. Agnew
Keyword(s):  
Fungicide Resistance ◽  
Strong Relationship ◽  
The Other ◽  
Erysiphe Necator ◽  
Colony Diameter ◽  
Quinone Outside Inhibitor ◽  
Grapevine Powdery Mildew ◽  
Dmi Fungicides ◽  
Grape Leaf ◽  
Demethylation Inhibitor

Isolates of Erysiphe necator from Hawkes Bay and Marlborough vineyards were tested for sensitivity to three demethylation inhibitor (DMI) fungicides (myclobutanil penconazole and cyproconazole) and one quinone outside inhibitor (QoI) fungicide (trifloxystrobin) Mean colony diameter was determined in a detached grape leaf assay for approximately 20 isolates per vineyard at 1 and 10 mg/litre of each fungicide Resistance to trifloxystrobin was prevalent in Hawkes Bay and Marlborough Mycobutanil resistance was found in both regions but particularly in Marlborough There was some loss of sensitivity to penconazole particularly in Marlborough Cyproconazole showed greater efficacy against E necator than the other two DMIs tested There was no explanation for the high trifloxystrobin resistance in sampled vineyards with few reports of trifloxystrobin use For DMIs there was a strong relationship between number of DMI fungicide applications over 10 years and DMI resistance across all three DMI active ingredients in both regions

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.

Prevention and Detection of Fungicide Resistance Development in Rhizoctonia zeae from Soybean and Corn in Nebraska

2021 ◽  
Author(s):  
Nikita Gambhir ◽  
Srikanth Kodati ◽  
Matthew Huff ◽  
Flávio Silva ◽  
Olutoyosi Ajayi-Oyetunde ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Resistance Management ◽  
Dry Weight ◽  
Geographic Region ◽  
Population Characteristics ◽  
Current Status ◽  
In Planta ◽  
Resistance Development ◽  
Rhizoctonia Zeae

The goal of this research was to advance the foundational knowledge required to quantify and mitigate fungicide resistance in Rhizoctonia zeae, the seedling disease pathogen of soybean and corn. In vitro sensitivity to azoxystrobin, fludioxonil, sedaxane, and/or prothioconazole was determined for 91 R. zeae isolates obtained mostly from soybean and corn fields in Nebraska. Isolates were sensitive to fludioxonil, sedaxane, and prothioconazole (EC50 < 3 µg/ml) and had a positively skewed EC50 distribution. Isolates were not sensitive to azoxystrobin in vitro (EC50 > 100 µg/ml) or in planta. Application of azoxystrobin did not significantly decrease disease severity or improve total dry weight of the soybean plants (P > 0.05). The risk of resistance development in R. zeae was estimated by characterizing its population structure. Eighty-one R. zeae isolates were genotyped using six microsatellite markers. Results showed that the population has a mixed mode of reproduction and is structured according to geographic region, suggesting limited dispersal. These population characteristics suggest that R. zeae has an intermediate risk of resistance development. Overall, this research established the current status of fungicide sensitivity in R. zeae in Nebraska and estimated its risk of resistance development, which can inform fungicide resistance management for R. zeae.

Sensitivity of C. fructicola and C. siamense of peach in China to multiple classes of fungicides and characterization of pyraclostrobin-resistant isolates

Plant Disease ◽  
2021 ◽  
Author(s):  
Hafiz Muhammad Usman ◽  
Qin Tan ◽  
Mohammad Mazharul Karim ◽  
Muhammad Adnan ◽  
Weixiao Yin ◽  
...  
Keyword(s):  
High Resistance ◽  
Mycelial Growth ◽  
Management Strategies ◽  
Cross Resistance ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Dmi Fungicides ◽  
Colletotrichum Gloeosporioides Species Complex ◽  
Cyt B Gene

Anthracnose, mainly caused by Colletotrichum gloeosporioides species complex including C. fructicola and C. siamense, is a devastating disease of peach. The chemical control has been widely used for years and management failures have increased towards commonly used fungicides. Therefore, screening of sensitivity of Colletotrichum spp. to fungicides with different modes of action is needed to make proper management strategies for peach anthracnose. In this study, sensitivity of 80 isolates of C. fructicola and C. siamense was screened for pyraclostrobin, procymidone, prochloraz and fludioxonil based on mycelial growth inhibition at discriminatory doses. Results showed that C. fructicola and C. siamense isolates were highly resistant to procymidone and fludioxonil with 100% resistance frequencies to both fungicides, but sensitive to prochloraz, i.e., no resistant isolates were found. For pyraclostrobin, 74% of C. fructicola isolates showed high resistance and 26 % were low resistant, all of the C. siamense isolates were low resistant. No positive cross-resistance was observed between pyraclostrobin and azoxystrobin, even they are members of the same quinone outside inhibitor (QoI) fungicide group, and between pyraclostrobin and non-QoIs. Resistant isolates to QoI fungicides were evaluated for the fitness penalty. Results showed that no significant differences except for mycelial growth rates were detected between highly resistant and low-resistant isolates of C. fructicola. Molecular characterization of Cyt b gene revealed that the G143A point mutation was the determinant of the high resistance in C. fructicola. This study demonstrated the current resistance status of C. fructicola and C. siamense to different fungicides and their future perspectives. Demethylation inhibitor (DMI) fungicides are the best option among different chemicals to control peach anthracnose in China.

scholarly journals Characterization of Quinone Outside Inhibitor Fungicide Resistance in Cercospora sojina and Development of Diagnostic Tools for its Identification

Plant Disease ◽  
2015 ◽  
Vol 99 (4) ◽  
pp. 544-550 ◽  
Author(s):  
F. Zeng ◽  
E. Arnao ◽  
G. Zhang ◽  
G. Olaya ◽  
J. Wullschleger ◽  
...  
Keyword(s):  
Cytochrome B ◽  
Leaf Spot ◽  
Fungicide Resistance ◽  
Cytochrome B Gene ◽  
Diagnostic Tools ◽  
Polymerase Chain Reaction Primer ◽  
Cercospora Sojina ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Frogeye Leaf Spot

Frogeye leaf spot of soybean, caused by the fungus Cercospora sojina, reduces soybean yields in most of the top-producing countries around the world. Control strategies for frogeye leaf spot can rely heavily on quinone outside inhibitor (QoI) fungicides. In 2010, QoI fungicide-resistant C. sojina isolates were identified in Tennessee for the first time. As the target of QoI fungicides, the cytochrome b gene present in fungal mitochondria has played a key role in the development of resistance to this fungicide class. The cytochrome b genes from three QoI-sensitive and three QoI-resistant C. sojina isolates were cloned and sequenced. The complete coding sequence of the cytochrome b gene was identified and found to encode 396 amino acids. The QoI-resistant C. sojina isolates contained the G143A mutation in the cytochrome b gene, a guanidine to cytosine transversion at the second position in codon 143 that causes an amino acid substitution of alanine for glycine. C. sojina-specific polymerase chain reaction primer sets and TaqMan probes were developed to efficiently discriminate QoI-resistant and -sensitive isolates. The molecular basis of QoI fungicide resistance in field isolates of C. sojina was identified as the G143A mutation, and specific molecular approaches were developed to discriminate and to track QoI-resistant and -sensitive isolates of C. sojina.

scholarly journals Population Structure, Fungicide Resistance Profile, and sdhB Mutation Frequency of Botrytis cinerea from Strawberry and Greenhouse-Grown Tomato in Greece

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 240-248 ◽  
Author(s):  
Sotirios Konstantinou ◽  
Thomas Veloukas ◽  
Michaela Leroch ◽  
George Menexes ◽  
Matthias Hahn ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Fungicide Resistance ◽  
Sensu Stricto ◽  
Sdhb Mutation ◽  
Resistance Development ◽  
Low Frequencies ◽  
Resistance Profile ◽  
Development Of Resistance ◽  
Crete Island ◽  
Of Greece

Botrytis cinerea is a pathogen with high genetic variability that has also shown high risk for fungicide resistance development. In total, 1,169 isolates obtained from strawberry (n = 297) and tomato (n = 872) in five geographic regions of Greece were tested for their sensitivity to several botryticides. A high frequency of isolates with multiple resistance to carbendazim, cyprodinil, pyraclostrobin, and boscalid was found in isolates from strawberry. In the isolates from tomato, the predominant phenotype was that of dual resistance to carbendazim and cyprodinil in the Crete island, of single resistance to carbendazim in the region of Preveza, and of sensitive isolates in the region of Kyparissia. None of the tested isolates was found to be fludioxonil resistant. High frequencies of boscalid-resistant phenotypes were observed in the strawberry isolates, while boscalid-resistance frequency in the tomato isolates was lower. H272R was the predominant sdhB mutation, associated with resistance to boscalid, in all the sampled isolates, while other sdhB mutations were found at low frequencies. B. cinerea group S, identified by the presence of a 21-bp insertion in the transcription factor mrr1 gene, was predominant within the tomato isolates obtained from all three sampled regions, with frequencies ranging from 62 to 75% of the isolates; whereas, within strawberry isolates, B. cinerea was predominant, with frequencies of 75 to 95%. Correlations of isolate genotype and fungicide resistance profile showed that B. cinerea sensu stricto isolates were more prone to the development of resistance to boscalid compared with the Botrytis group S isolates, which may explain the observed predominance of B. cinerea sensu stricto in strawberry fields.

scholarly journals Succinate dehydrogenase inhibitor (SDHI) fungicide resistance prevention strategy

2011 ◽  
Vol 64 ◽  
pp. 119-124 ◽  
Author(s):  
A.H. McKay ◽  
G.C. Hagerty ◽  
G.B. Follas ◽  
M.S. Moore ◽  
M.S. Christie ◽  
...  
Keyword(s):  
New Zealand ◽  
High Risk ◽  
Succinate Dehydrogenase ◽  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Resistance Management ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Action Committee ◽  
Succinate Dehydrogenase Inhibitor

Succinate dehydrogenase inhibitor (SDHI) fungicides are currently represented in New Zealand by eight active ingredients bixafen boscalid carboxin fluaxapyroxad fluopyram isopyrazam penthiopyrad and sedaxane They are either currently registered or undergoing development in New Zealand for use against a range of ascomycete and basiodiomycete pathogens in crops including cereals ryegrass seed apples pears grapes stonefruit cucurbits and kiwifruit These fungicides are considered to have medium to high risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for use of SDHI fungicides in New Zealand to help avoid or delay the development of resistance in the fungal pathogens that they target

Sign in / Sign up

Export Citation Format

Share Document