scholarly journals Fitness of Erysiphe necator with G143A-Based Resistance to Quinone Outside Inhibitors

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1494-1502 ◽  
Author(s):  
Lynn Esther E. Rallos ◽  
Nels G. Johnson ◽  
David G. Schmale ◽  
Aaron J. Prussin ◽  
Anton B. Baudoin
Keyword(s):  
Powdery Mildew ◽  
Quantitative Polymerase Chain Reaction ◽  
Field Trials ◽  
Resistance Development ◽  
Erysiphe Necator ◽  
Potted Plants ◽  
Sterol Demethylation Inhibitors ◽  
Quinone Outside Inhibitors ◽  
Competition Assays ◽  
Qoi Resistance

Management of grape powdery mildew (Erysiphe necator) using quinone outside inhibitors (QoIs) has eroded in an increasing number of regions due to resistance development. To determine persistence of resistance when QoIs are withdrawn, competition assays were conducted on unsprayed grape plants (Vitis vinifera ‘Chardonnay’) by cycling mixtures of resistant and sensitive isolates characterized as genetically diverse based on microsatellite analyses. Under laboratory conditions, %G143A, quantified by quantitative polymerase chain reaction (qPCR), increased significantly, indicating competitiveness of the resistant fraction. To confirm competitiveness in the field, trials using potted plants were conducted. Percent G143A tended to decrease in one growing season, probably due to spore migration and mixing of populations with natural background inoculum. In a second season, QoI resistance persisted at high frequency for 4 weeks. Resistant populations were also found to persist in one vineyard without QoI application for four consecutive years. The frequency was still about 25% in the fourth year, with higher frequency (36%) in a hotspot section. QoI-resistant populations with >5% G143A also harbored Y136F in the cyp51 gene that confers some resistance to sterol demethylation inhibitors, another fungicide class for powdery mildew control. Double resistance could have been partly responsible for persistence of QoI resistance at this location.

scholarly journals Strobilurin (QoI) Resistance in Populations of Erysiphe necator on Grapes in Michigan

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1621-1628 ◽  
Author(s):  
L. A. Miles ◽  
T. D. Miles ◽  
W. W. Kirk ◽  
A. M. C. Schilder
Keyword(s):  
Powdery Mildew ◽  
Fungicide Resistance ◽  
Resistance Management ◽  
The United States ◽  
Suboptimal Control ◽  
Single Nucleotide ◽  
Erysiphe Necator ◽  
Nucleotide Mutation ◽  
Conidium Germination ◽  
Qoi Resistance

Powdery mildew, caused by Erysiphe necator, is the most common and destructive disease of grapes (Vitis spp.) worldwide. In Michigan, it is primarily controlled with fungicides, including strobilurins (quinone outside inhibitors [QoIs]). Within the United States, resistance to this class of fungicides has been reported in E. necator populations in some east coast states. Among 12 E. necator isolates collected from five Michigan vineyards in 2008, one carried the G143A single-nucleotide mutation responsible for QoI resistance. This isolate was confirmed to be resistant in a conidium germination assay on water agar amended with trifloxystrobin at 0.001, 0.01, 0.1, 1, 10, or 100 μg/ml and salicylhydroxamic acid (100 mg/liter). The mutant isolate was able to germinate on media amended with 100 μg/ml trifloxystrobin, whereas a representative wild-type isolate did not germinate at concentrations higher than 0.1 μg/ml. In 2009, 172 isolates were collected from a total of 21 vineyards (juice and wine grapes): three vineyards with no fungicide application history (baseline sites), six research vineyards, and 12 commercial vineyards. QoI resistance was defined as the effective concentration that inhibited 50% of conidial germination (EC50) > 1 μg/ml. Isolates from baseline sites had EC50 values mostly below 0.01 μg/ml, while isolates that were highly resistant to trifloxystrobin (EC50 > 100 μg/ml) occurred in five research and three commercial wine grape vineyards at frequencies of 40 to 100% and 25 to 75% of the isolates, respectively. The G143A mutation was detected in every isolate with an EC50 > 1 μg/ml. These results suggest that fungicide resistance may play a role in suboptimal control of powdery mildew observed in some Michigan vineyards and emphasizes the need for continued fungicide resistance management.

scholarly journals Evaluation of Quinoxyfen Resistance of Erysiphe necator (Grape Powdery Mildew) in a Single Virginia Vineyard

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2586-2591 ◽  
Author(s):  
Xuewen Feng ◽  
Mizuho Nita ◽  
Anton B. Baudoin
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Disease Control ◽  
Low Dose ◽  
Disease Incidence ◽  
The United States ◽  
Field Trials ◽  
Erysiphe Necator ◽  
Late Season ◽  
Grape Powdery Mildew

The protectant fungicide quinoxyfen has been used against grape powdery mildew (Erysiphe necator) in the United States since 2003. In 2013, isolates of grape powdery mildew with reduced quinoxyfen sensitivity (here designated as quinoxyfen lab resistance or QLR) were detected in a single vineyard in western Virginia, USA. Field trials were conducted in 2014, 2015, and 2016 at the affected vineyard to determine to what extent quinoxyfen might still contribute to disease control. Powdery mildew control by quinoxyfen was similar to, or only slightly less than, that provided by myclobutanil and boscalid in all three years. In 2016, early- versus late-season applications of quinoxyfen were compared to test the hypothesis that early-season applications were more effective, but differences were small. A treatment with two early quinoxyfen applications, at bloom and 2 weeks later, followed by a myclobutanil-boscalid plus a low dose of sulfur rotation provided slightly better control of foliar disease incidence than treatments containing four quinoxyfen applications or two midseason or two late quinoxyfen applications supplemented by myclobutanil and boscalid applications; severity differences were small and nonsignificant. Metrafenone and benzovindiflupyr generally provided excellent powdery mildew control. The frequency of QLR in vines not treated with quinoxyfen slowly declined from 65% in 2014 to 46% in 2016. Further research is needed to explain how, despite this QLR frequency, quinoxyfen applied to grapes in the field was still able to effectively control powdery mildew.

scholarly journals Testing of paraffin oil efficiency against grape powdery mildew in Eger wine region

2016 ◽  
pp. 73-80
Author(s):  
Xénia Pálfi ◽  
Dénes Bisztray ◽  
Szabolcs Villangó ◽  
Zita Pálfi ◽  
Tamás Deák ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Downy Mildew ◽  
Plasmopara Viticola ◽  
Field Trials ◽  
Intensity Of Infection ◽  
Erysiphe Necator ◽  
Regular Treatment ◽  
Paraffin Oil ◽  
Wine Region ◽  
Grape Varieties

The aim of the present study was to examine the efficiency of paraffin oil against powdery mildew in Eger wine region. The experiment has been carried out in 2013 and 2014 with Chardonnay and Kékfrankos grape varieties, which have different resistance against powdery mildew. The effectiveness of the oil was examined on leaves and clusters (frequency and intensity). This oil was effective against Erysiphe necator infection on field trials in Chile and Brazil. The spread of downy mildew (Plasmopara viticola) was also inhibited by this material in some experiments conducted in Spain and France. The differences between oil treatments represented the sensitivity of the grape varieties in accordance with the applied dosages. The oil was effective against powdery mildew with different extent as a result of the so called ”vintage effect”. In 2013, the treatment of the highest dosage (D3) didn’t differed significantly in frequency and intensity of infection from the regular treatment (clusters of Kékfrankos, leaves of Chardonnay). In 2014, the oil was not so effective against powdery mildew compared to 2013. No remarkable differences were detected between the treatments due to the strong pressure of powdery mildew. Furthermore, no any effect of the lowest dosage (D1) was detected in the case of the sensitive clusters of Chardonnay and leaves of Kékfrankos in both experimental years. In summary, the oil treatment has an effect against powdery mildew, however this efficiency largely depends on the vintage characteristics and the pressure of powdery mildew. Further investigations are neccessary, for example field trials with combinations of other sprays. The oil can be useable as fungicide with proper care in eco-friendly integrated and bio (ecological) viticulture.

scholarly journals Fungicide Resistance in Powdery Mildew Fungi

2020 ◽  
Vol 8 (9) ◽  
pp. 1431
Author(s):  
Alejandra Vielba-Fernández ◽  
Álvaro Polonio ◽  
Laura Ruiz-Jiménez ◽  
Antonio de Vicente ◽  
Alejandro Pérez-García ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Powdery Mildews ◽  
Powdery Mildew Fungi ◽  
Sterol Demethylation Inhibitors ◽  
Chemical Groups ◽  
Multiple Chemical

Powdery mildew fungi (Erysiphales) are among the most common and important plant fungal pathogens. These fungi are obligate biotrophic parasites that attack nearly 10,000 species of angiosperms, including major crops, such as cereals and grapes. Although cultural and biological practices may reduce the risk of infection by powdery mildew, they do not provide sufficient protection. Therefore, in practice, chemical control, including the use of fungicides from multiple chemical groups, is the most effective tool for managing powdery mildew. Unfortunately, the risk of resistance development is high because typical spray programs include multiple applications per season. In addition, some of the most economically destructive species of powdery mildew fungi are considered to be high-risk pathogens and are able to develop resistance to several chemical classes within a few years. This situation has decreased the efficacy of the major fungicide classes, such as sterol demethylation inhibitors, quinone outside inhibitors and succinate dehydrogenase inhibitors, that are employed against powdery mildews. In this review, we present cases of reduction in sensitivity, development of resistance and failure of control by fungicides that have been or are being used to manage powdery mildew. In addition, the molecular mechanisms underlying resistance to fungicides are also outlined. Finally, a number of recommendations are provided to decrease the probability of resistance development when fungicides are employed.

scholarly journals QoI Resistance in Sugar Beet Powdery Mildew (Erysiphe betae) in Scandinavia

2019 ◽  
Vol 20 (3) ◽  
pp. 179-179 ◽  
Author(s):  
Thies Marten Heick ◽  
Anne Lisbet Hansen ◽  
Annemarie Fejer Justesen ◽  
Lise Nistrup Jørgensen
Keyword(s):  
Powdery Mildew ◽  
Sugar Beet ◽  
The United States ◽  
Field Trials ◽  
Active Ingredients ◽  
Management Measures ◽  
Real Risk ◽  
Erysiphe Betae ◽  
European Union Legislation ◽  
Qoi Resistance

Powdery mildew caused by Erysiphe betae is one of the major fungal diseases in sugar beet in Denmark and Sweden. Frequent applications of fungicides mitigate the risk of powdery mildew epidemics and, consequently, reduce yield losses conferred by the disease. So far, mixtures of quinone outside inhibitors (QoIs) and triazoles have provided good efficacy against E. betae in field trials and common farming practice. However, development of fungicide resistance is a real risk, because only a limited number of active ingredients are available for the control of powdery mildew in sugar beet, and several other active ingredients are expected to be banned following reevaluation when the most recent European Union legislation is implemented. The G143A mutation associated with QoI resistance has been previously found in the United States. In this brief, its presence in Europe is reported for the first time. The current finding strongly encourages the adoption of anti-resistance strategies that minimize the spread of QoI resistance in sugar beet powdery mildew. Those strategies should be based on integrated pest management measures, including disease monitoring, the use of resistant cultivars, and the use of biological products. A sole reliance on QoI fungicides for sugar beet powdery mildew control should be avoided.

scholarly journals A Novel Homeobox-Like Gene Associated with Reaction to Stripe Rust and Powdery Mildew in Common Wheat

2008 ◽  
Vol 98 (12) ◽  
pp. 1291-1296 ◽  
Author(s):  
D. Liu ◽  
X.-C. Xia ◽  
Z.-H. He ◽  
S.-C. Xu
Keyword(s):  
Powdery Mildew ◽  
Common Wheat ◽  
Stripe Rust ◽  
Puccinia Striiformis ◽  
Quantitative Polymerase Chain Reaction ◽  
Field Trials ◽  
Adult Plant ◽  
Aflp Analysis ◽  
Gene Encoding ◽  
Polymerase Chain

Stripe rust and powdery mildew, caused by Puccinia striiformis f. sp. tritici and Blumeria graminis f. sp. tritici, respectively, are severe diseases in wheat (Triticum aestivum) worldwide. In our study, differential amplification of a 201-bp cDNA fragment was obtained in a cDNA-amplified fragment length polymorphism (AFLP) analysis between near-isogenic lines Yr10NIL and Avocet S, inoculated with P. striiformis f. sp. tritici race CYR29. A full-length cDNA (1,357 bp) of a homeobox-like gene, TaHLRG (GenBank accession no. EU385606), was obtained in common wheat based on the sequence of GenBank accession AW448633 with high similarity to the above fragment. The genomic DNA sequence (2,396 bp) of TaHLRG contains three exons and two introns. TaHLRG appeared to be a novel homeobox-like gene, encoding a protein with a predicted 66-amino-acid homeobox domain. It was involved in race-specific responses to stripe rust in real-time quantitative polymerase chain reaction (PCR) analyses with Yr9NIL, Yr10NIL, and Avocet S. It was also associated with adult-plant resistance to stripe rust and powdery mildew based on the field trials of doubled haploid lines derived from the cross Bainong 64/Jingshuang 16 and two F2:3 populations from the crosses Lumai 21/Jingshuang 16 and Strampelli/Huixianhong. A functional marker, THR1 was developed based on the sequence of TaHLRG and located on chromosome 6A using a set of Chinese Spring nulli-tetrasomic lines.

scholarly journals Evaluation of Rotational Biopesticide Programs for Disease Management in Organic Cucurbit Production

Plant Disease ◽  
2016 ◽  
Vol 100 (11) ◽  
pp. 2226-2233 ◽  
Author(s):  
Sasha C. Marine ◽  
Mason J. Newark ◽  
Robert C. Korir ◽  
Kathryne L. Everts
Keyword(s):  
Disease Management ◽  
Powdery Mildew ◽  
Field Trials ◽  
Management Program ◽  
Organic Production ◽  
Podosphaera Xanthii ◽  
Management Option ◽  
Resistance Development ◽  
Pathogen Populations ◽  
Organically Managed

Downy mildew (Pseudoperonospora cubensis) and powdery mildew (Podosphaera xanthii) are two of the most economically important and widespread cucurbit diseases. Disease management relies primarily on fungicide use, but frequent fungicide applications can lead to the development of resistant pathogen populations. In addition, more vegetables are being produced with organic practices, which prohibit the use of many fungicides. Incorporating biorational products into a disease management program may help mitigate the risk of fungicide resistance development while being compatible with organic production. Field trials were conducted for two years on organically managed land in Maryland with cucumber, muskmelon, pumpkin, and butternut squash to evaluate the efficacy of four biorational products (i.e., Actinovate AG, OxiDate, Regalia, and Serenade Soil) when applied in a rotational program with copper against foliar cucurbit diseases. Generally, all biorational treatments resulted in significantly lower downy and powdery mildew severity compared with the nontreated plants, but the level of disease management was not significantly different than that provided by copper alone. However, Actinovate AG, OxiDate, and Serenade Soil each improved disease management on at least one crop, as compared with copper alone. Rotational programs with biopesticides are a viable disease management option for organic production of field-grown cucurbits in Maryland.

scholarly journals Indirect effect of fungicide treatments on chasmothecia of Erysiphe necator Schwein overwintering on grapevine bark

2012 ◽  
Vol 48 (No. 1) ◽  
pp. 21-30 ◽  
Author(s):  
P. Hoffmann ◽  
I. Füzi ◽  
F. Virányi
Keyword(s):  
Powdery Mildew ◽  
Field Trials ◽  
Vitis Vinifera L ◽  
Significant Activity ◽  
Erysiphe Necator ◽  
Large Numbers ◽  
Leaf Infection ◽  
Autumn Leaf ◽  
Powdery Mildew Infection ◽  
Made In

Erysiphe necator Schwein overwinters in Hungary primarily as large numbers of chasmothecia providing primary inoculum for grapevine (Vitis vinifera L.) infection in the next year. In two field trials, the effect of fungicide treatments on powdery mildew severity and the number of chasmothecia produced on leaves and washed to the bark were studied. In 2005, the number of chasmothecia harvested from the bark showed a limited correlation with disease severity (r = 0.553) and number of chasmothecia on leaves (r = 0.600). In 2006, using a refined sieving technique, a substantial increase in the number of harvested chasmothecia could be achieved resulting in a much closer correlation between the variables above (r = 0.750 and r = 0.886, respectively). Among the fungicides applied, boscalid and fluquinconazole (SC formulation) showed the most significant activity by decreasing both the autumn leaf infection and the formation of chasmothecia on the leaves and providing the lowest number of chasmothecia on bark. The research underlined the importance of fungicide applications made in the previous year to decrease the amount of overwintering inoculum and to help protect grapevines from powdery mildew infection in the next year.  

scholarly journals Continuous Lighting Reduces Conidial Production and Germinability in the Rose Powdery Mildew Pathosystem

Plant Disease ◽  
2010 ◽  
Vol 94 (3) ◽  
pp. 339-344 ◽  
Author(s):  
A. Suthaparan ◽  
Arne Stensvand ◽  
S. Torre ◽  
Maria L. Herrero ◽  
R. I. Pettersen ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Interspecific Hybrid ◽  
Day Length ◽  
Artificial Light ◽  
Potted Plants ◽  
Severity Of Disease ◽  
Detached Leaves ◽  
Growth Chambers ◽  
The Rose

The effect of day length on production and germinability of conidia and severity of disease caused by Podosphaera pannosa, the causal agent of rose powdery mildew, was studied. Whole potted plants or detached leaves of Rosa interspecific hybrid ‘Mistral’ were inoculated with P. pannosa and exposed to 0, 12, 18, 20, 22, or 24 h of artificial light per day in growth chambers equipped with mercury lamps. Increasing duration of illumination from 18 to 20 to 24 h per day reduced production of conidia by 22 to 62%. Exposure to 24 h of illumination per day also strongly reduced disease severity compared with 18 h. Our results suggest that increasing day lengths from 18 h per day to 20 to 24 h may suppress the disease significantly and, thereby, reduce the need for fungicide applications against powdery mildew.

scholarly journals Identification of Race-Specific Resistance in North American Vitis spp. Limiting Erysiphe necator Hyphal Growth

2012 ◽  
Vol 102 (1) ◽  
pp. 83-93 ◽  
Author(s):  
David W. Ramming ◽  
Franka Gabler ◽  
Joseph L. Smilanick ◽  
Dennis A. Margosan ◽  
Molly Cadle-Davidson ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Resistance Genes ◽  
Specific Resistance ◽  
Hyphal Growth ◽  
Resistance Mechanisms ◽  
Hybrid Breeding ◽  
Erysiphe Necator ◽  
Vitis Rotundifolia ◽  
Resistance Sources

Race-specific resistance against powdery mildews is well documented in small grains but, in other crops such as grapevine, controlled analysis of host–pathogen interactions on resistant plants is uncommon. In the current study, we attempted to confirm powdery mildew resistance phenotypes through vineyard, greenhouse, and in vitro inoculations for test cross-mapping populations for two resistance sources: (i) a complex hybrid breeding line, ‘Bloodworth 81-107-11', of at least Vitis rotundifolia, V. vinifera, V. berlandieri, V. rupestris, V. labrusca, and V. aestivalis background; and (ii) Vitis hybrid ‘Tamiami’ of V. aestivalis and V. vinifera origin. Statistical analysis of vineyard resistance data suggested the segregation of two and three race-specific resistance genes from the two sources, respectively. However, in each population, some resistant progeny were susceptible in greenhouse or in vitro screens, which suggested the presence of Erysiphe necator isolates virulent on progeny segregating for one or more resistance genes. Controlled inoculation of resistant and susceptible progeny with a diverse set of E. necator isolates clearly demonstrated the presence of fungal races differentially interacting with race-specific resistance genes, providing proof of race specificity in the grape powdery mildew pathosystem. Consistent with known race-specific resistance mechanisms, both resistance sources were characterized by programmed cell death of host epidermal cells under appressoria, which arrested or slowed hyphal growth; this response was also accompanied by collapse of conidia, germ tubes, appressoria, and secondary hyphae. The observation of prevalent isolates virulent on progeny with multiple race-specific resistance genes before resistance gene deployment has implications for grape breeding strategies. We suggest that grape breeders should characterize the mechanisms of resistance and pyramid multiple resistance genes with different mechanisms for improved durability.

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