Fungicide efficacy of dry bean white mold [Sclerotinia sclerotiorum (Lib.) de Bary, causal organism] and economic analysis at moderate to high disease pressure

White mold (WM) caused by Sclerotinia sclerotiorum (Lib.) de Bary is the most devastating disease of common bean (dry and snap or garden bean) (Phaseolus vulgaris L.) in North America. The use of a reliable screening method (SM) in common bean is crucial to improve physiological resistance to WM. The objective of this study was to compare the efficacy of three SM to identify physiological resistance in dry bean genotypes with different evolutionary origins and levels of resistance. Screening methods tested were: (i) the modified straw test or cut–stem (CSM); (ii) infected bean flower (IFL); and (iii) infected oat seed (IOS). A 195, ICA Bunsi, Othello, and VCW 54 dry bean were tested with the three SM. The experimental design was a split plot in randomized complete blocks with three replications in 2007 and 2008. Two independent inoculations 1 wk apart for each SM were made. The WM reaction was scored at 16, 23, and 33 d post-inoculation (DPI) using a 1 to 9 scale. There were highly significant differences between SM and its interaction with years. The CSM and IFL were the most consistent and highly correlated (r > 0.70, P < 0.01). Interspecific breeding line VCW 54 consistently had the highest WM resistance across years, SM, and evaluation dates, followed by A 195. White mold scores increased with delayed evaluations. Thus, CSM or IFL with disease assessed 33 DPI should be used for identifying common bean genotypes with high levels of physiological resistance to WM.Key words: Common bean, growth habit, race Mesoamerica, race Nueva Granada, Phaseolus vulgaris, Sclerotinia sclerotiorum

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Screening for Partial Physiological Resistance to White Mold in Dry Bean Using Excised Stems

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.117.2.321 ◽

1992 ◽

Vol 117 (2) ◽

pp. 321-327 ◽

Cited By ~ 16

Author(s):

P.N. Miklas ◽

K.F. Grafton ◽

B.D. Nelson

Keyword(s):

Phaseolus Vulgaris ◽

Sclerotinia Sclerotiorum ◽

Field Resistance ◽

White Mold ◽

Lesion Length ◽

Laboratory Procedure ◽

Dry Bean ◽

Snap Bean ◽

Breeding Lines ◽

Physiological Resistance

A laboratory procedure was tested to determine whether excised stems would allow a reliable indication of partial physiological resistance (PPR) to white mold [Sclerotinia sclerotiorum (Lib.) deBary] in dry bean (Phaseolus vulgaris L.). Excised stems from 11- and 28-day-old plants were inoculated with growing mycelium of S. sclerotiorum, incubated for 4 to 7 days (11- and 28-day assays, respectively), then assayed for lesion length (LL). A total of 15 bean genotypes were screened for PPR, as indicated by LL. Significant (P < 0.05) differences among LL means of small- and medium-seeded bean genotypes were detected in the 28-day assay, whereas only LL means among medium-seeded genotypes. differed significantly (P < 0.05) in the n-day assay. `Bunsi', `C-20', `Sierra', `Topaz', and snap bean breeding lines NY 5262, NY 5394, and NY 5403 had the highest PPR and `Upland', D76125, and `UI-114' the lowest. The results from both assays were repeatable. A moderately high correlation (r = 0.68, P < 0.02) was observed between PPR and field resistance. The 28-day assay has potential for evaluating dry bean germplasm for PPR to white mold disease caused by S. sclerotiorum. A 28-day assay also was used to measure virulence of 18 isolates of S. sclerotiorum. The 18 isolates did not differ (P < 0.05) for virulence when measured by LL. The lack of any genotype × isolate interaction for LL indicated lack of host-pathogen specificity.

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Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean (Phaseolus vulgaris) in the United States

PeerJ ◽

10.7717/peerj.4152 ◽

2017 ◽

Vol 5 ◽

pp. e4152 ◽

Cited By ~ 15

Author(s):

Zhian N. Kamvar ◽

B. Sajeewa Amaradasa ◽

Rachana Jhala ◽

Serena McCoy ◽

James R. Steadman ◽

...

Keyword(s):

United States ◽

Genetic Diversity ◽

Sclerotinia Sclerotiorum ◽

Genotypic Variation ◽

The United States ◽

White Mold ◽

Bipartite Network ◽

Necrotrophic Pathogen ◽

Dry Bean ◽

Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries (wmn) with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries (a) reflect the genetic diversity of the populations in the surrounding region and (b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and wmn surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n = 18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several wmn across the United States to account for both the phenotypic and genotypic variation that exists across regions.

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Variation in Sclerotinia sclerotiorum Bean Isolates from Multisite Resistance Screening Locations

Plant Disease ◽

10.1094/pdis-11-10-0865 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1370-1377 ◽

Cited By ~ 28

Author(s):

Lindsey Otto-Hanson ◽

James R. Steadman ◽

Rebecca Higgins ◽

Kent M. Eskridge

Keyword(s):

Sclerotinia Sclerotiorum ◽

The United States ◽

White Mold ◽

Resistance Screening ◽

Dry Bean ◽

Mycelial Compatibility ◽

Greenhouse Screening ◽

Mold Resistance ◽

Production Areas ◽

Resistance Expression

There is no complete resistance to Sclerotinia sclerotiorum, cause of white mold in dry bean (Phaseolus vulgaris). Variable resistance expression is one problem in screening for improved white mold resistance. With no previous information in the literature, pathogen variation in multisite screening nurseries was evaluated as one cause of diverse resistance expression. In all, 10 isolates of S. sclerotiorum used in greenhouse screening and 146 isolates collected from nine white mold field screening nurseries in major bean production areas in the United States were compared using mycelial compatibility groupings (MCGs) and an aggressiveness test. These 10 greenhouse screening isolates formed six MCGs. Among 156 field and greenhouse isolates, 64 MCGs were identified and 36 of those were each composed of a single unique isolate. Significant differences in isolate aggressiveness were found between some isolates in different MCGs but the isolates within an MCG did not differ in aggressiveness. High isolate variation found within and between field locations could influence the disease phenotype of putative white mold resistant germplasm. We next compared genotype and phenotype of isolates from screening nurseries and those from producer fields. Variability found in and among screening locations did reflect variability found in the four producer fields sampled. White mold resistance screening can be improved by knowledge of isolate genotypic and phenotypic characteristics.

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Response of dry bean white mould [Sclerotinia sclerotiorum (Lib.) de Bary, causal organism] to fungicides

Canadian Journal of Plant Science ◽

10.4141/cjps2013-311 ◽

2014 ◽

Vol 94 (5) ◽

pp. 905-910 ◽

Cited By ~ 12

Author(s):

K. J. Mahoney ◽

C. M. McCreary ◽

C. L. Gillard

Keyword(s):

Bacillus Subtilis ◽

Sclerotinia Sclerotiorum ◽

Disease Incidence ◽

Yield Potential ◽

Causal Organism ◽

Dry Bean ◽

Thiophanate Methyl ◽

White Mould ◽

Progress Curve ◽

Serious Disease

Mahoney, K. J., McCreary, C. M. and Gillard, C. L. 2014. Response of dry bean white mould [ Sclerotinia sclerotiorum (Lib.) de Bary, causal organism] to fungicides. Can. J. Plant Sci. 94: 905–910. White mould [Sclerotinia sclerotiorum (Lib.) de Bary, causal organism] is a serious disease of dry bean (Phaseolus vulgaris L.). Producers frequently rely on preventative fungicides, yet, this represents a significant production cost. Studies were conducted in 2009, 2010, and 2011 to determine fungicide efficacy under conditions optimized for white mould. Disease incidence×severity ratings were used to calculate the area under the disease progress curve (AUDPC). After harvest, a return on investment (ROI) was calculated. AUDPC values were similar across boscalid, fluazinam, fluopyram, and thiophanate-methyl and lower than Bacillus subtilis, CaCl2, and the untreated. Yield was greatest for fluazinam and fluopyram, followed by thiophanate-methyl. Bacillus subtilis and CaCl2 yields were similar to the untreated. In early-planted environments, using fluazinam and fluopyram resulted in a $500 ha−1 greater ROI than the untreated with $554 gained for every tonne per hectare of dry bean harvested. In late-planted environments, fluazinam and fluopyram averaged about $200 ha−1 greater ROI than the untreated and $494 was returned for every tonne per hectare of dry bean. When dry bean yield potential is reduced under conditions of increased white mould severity, profit margins become narrowed and producers may have to select fungicides that are both efficacious and economical.

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Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean (Phaseolus vulgaris) in the United States

10.7287/peerj.preprints.3311 ◽

2017 ◽

Author(s):

Zhian N Kamvar ◽

Bimal S Amaradasa ◽

Rachana Jhala ◽

Serena McCoy ◽

James R Steadman ◽

...

Keyword(s):

United States ◽

Genetic Diversity ◽

Sclerotinia Sclerotiorum ◽

Genotypic Variation ◽

The United States ◽

White Mold ◽

Bipartite Network ◽

Necrotrophic Pathogen ◽

Dry Bean ◽

Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries a) reflect the genetic diversity of the populations in the surrounding region and b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and white mold screening nurseries surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n=18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several white mold screening nurseries across the US to account for both the phenotypic and genotypic variation that exists across regions.

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Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean in the United States

10.7287/peerj.preprints.3311v1 ◽

2017 ◽

Author(s):

Zhian N Kamvar ◽

Bimal S Amaradasa ◽

Rachana Jhala ◽

Serena McCoy ◽

James R Steadman ◽

...

Keyword(s):

Genetic Diversity ◽

Sclerotinia Sclerotiorum ◽

Genotypic Variation ◽

Natural Populations ◽

The United States ◽

White Mold ◽

Bipartite Network ◽

Necrotrophic Pathogen ◽

Dry Bean ◽

Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries a) reflect the genetic diversity of the populations in the surrounding region and b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and white mold screening nurseries surveyed over 10 years in 2003–2012 representing 11 states, Mexico, France, and Australia at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n=18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several white mold screening nurseries across the US to account for both the phenotypic and genotypic variation that exists across regions.

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Response of lentil cultivars to Sclerotinia white mold and Botrytis grey mould infection under irrigated and dryland conditions

Canadian Journal of Plant Science ◽

10.1139/cjps-2020-0335 ◽

2021 ◽

Author(s):

Kazi Kader ◽

Scott Erickson ◽

Robyne Bowness ◽

Mark A Olson ◽

Syama Chatterton

Keyword(s):

Sclerotinia Sclerotiorum ◽

Disease Incidence ◽

Grey Mould ◽

Field Trials ◽

Limiting Factors ◽

White Mold ◽

Limiting Factor ◽

Dry Land ◽

Grey Mold ◽

Disease Pressure

Diseases such as Sclerotinia white mold (SWM) caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary and Botrytis grey mold (BGM) caused by the fungus Botrytis cinerea Pers. may be limiting factors for lentil production in wetter areas of Alberta, Canada. Field trials were conducted at the Lethbridge Research and Development Centre from 2013-2015 to evaluate the response of lentil cultivars to SWM and BGM and yield impacts. Ten lentil cultivars from five market classes were evaluated under irrigated and dry land plots with two planting densities (120 plants m-2 and 160 plants m-2).Year and irrigation had the largest effect on disease incidence, with highest SWM incidence occurring under irrigation in 2013, followed by 2014 and 2015. Conversely, BGM incidence under irrigation was highest in 2015 and lowest in 2013, but levels were lower than SWM. Significantly (P <0.05) lower disease incidences were observed in dryland plots, which also produced higher yield than irrigated plots. Cultivars varied significantly in SWM incidence and yield under irrigated and dryland conditions, perhaps due to variable disease pressure, but there was no consistent trend in cultivar performance. BGM incidence was similar in cultivars, but differed among years. These findings indicate that SWM may be a limiting factor to lentil production in wetter areas, as the ten cultivars from five market classes tested were all highly susceptible to SWM.

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Population structure and phenotypic variation of Sclerotinia sclerotiorum from dry bean (Phaseolus vulgaris) in the United States

10.7287/peerj.preprints.3311v2 ◽

2017 ◽

Author(s):

Zhian N Kamvar ◽

Bimal S Amaradasa ◽

Rachana Jhala ◽

Serena McCoy ◽

James R Steadman ◽

...

Keyword(s):

United States ◽

Genetic Diversity ◽

Sclerotinia Sclerotiorum ◽

Genotypic Variation ◽

The United States ◽

White Mold ◽

Bipartite Network ◽

Necrotrophic Pathogen ◽

Dry Bean ◽

Field Source

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries a) reflect the genetic diversity of the populations in the surrounding region and b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns. We genotyped 366 isolates of S. sclerotiorum from producer fields and white mold screening nurseries surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n=18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several white mold screening nurseries across the US to account for both the phenotypic and genotypic variation that exists across regions.

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