Detection of Leptosphaeria maculans and Leptosphaeria biglobosa Causing Blackleg Disease in Canola from Canadian Canola Seed Lots and Dockage

Fernando, W. G. Dilantha; Zhang, Xuehua; Amarasinghe, Chami C.

doi:10.3390/plants5010012

Cited by 30 publications

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“…The epidemiology of blackleg differs between continents and regions because of differences in climate, growing season, cultivars and especially fungal populations (West et al 2001;Fitt et al 2006). Although the incidence of seed infection by L. maculans and L. biglobosa is relatively low, seed-borne inoculum is a major concern in transporting L. maculans into countries where L. maculans has not been identified, such as China (Fitt et al 2006;Zhang et al 2014;Fernando et al 2016;Van de Wouw et al 2016a, 2016b.…”

Section: Introductionmentioning

confidence: 99%

Insights into fighting against blackleg disease of Brassica napus in Canada

Zhang

Fernando

2018

Crop Pasture Sci.

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Abstract. Blackleg disease, caused by the ascomycete fungal pathogen Leptosphaeria maculans, is a devastating disease of canola (Brassica napus) in Australia, Canada and Europe. Although cultural strategies such as crop rotation, fungicide application, and tillage are adopted to control the disease, the most promising disease control strategy is the utilisation of resistant canola varieties. However, field populations of L. maculans display a high evolutionary potential and are able to overcome major resistance genes within a few years, making disease control relying on resistant varieties challenging. In the early 1990s, blackleg resistance gene Rlm3 was introduced into Canadian canola varieties and provided good resistance against the fungal populations until the early 2000s, when moderate to severe blackleg outbreaks were observed in some areas across western Canada. However, the breakdown of Rlm3 resistance was not reported until recently, based on studies on R genes present in Canadian canola varieties and the avirulence allele frequency in L. maculans populations in western Canada. The fact that Rlm3 was overcome by the evolution of fungal populations demands canola breeding programs in Canada to be prepared to develop canola varieties with diversified and efficient R genes. In addition, frequent monitoring of fungal populations can provide up-to-date guidance for proper resistance genes deployment. This literature review provides insights into the outbreaks and management of blackleg disease in Canada.

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Section: Introductionmentioning

confidence: 99%

Insights into fighting against blackleg disease of Brassica napus in Canada

Zhang

Fernando

2018

Crop Pasture Sci.

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“…It is an important disease in canola ( Brassica napus ) and other cruciferous crops in Europe, Australia and Canada (Balesdent, Louvard, Pinochet, & Rouxel, ). In Canada, canola is the most important cash crop with a production of approximately 13.5 million tonnes in 2015 (Fernando, Zhang, & Amarasinghe, ). Blackleg disease has been reported to result in great yield losses in canola production in western Canada.…”

Section: Introductionmentioning

confidence: 99%

Distribution of mating‐type alleles and genetic variability in field populations of Leptosphaeria maculans in western Canada

Zou

Zhang

Fernando

2018

Journal of Phytopathology

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Leptosphaeria maculans is the most important fungal pathogen of canola (Brassica napus, oilseed rape) that causes the devastating stem canker in canola fields of western Canada. The population genetic structure of L. maculans, represented by nine subpopulations from a 6‐year period and three different provinces in western Canada, was determined using ten minisatellite markers. Isolates collected at different locations in six consecutive years had an even distribution of MAT1‐1 and MAT1‐2 across the nine subpopulations. All subpopulations of L. maculans exhibited a moderate gene diversity (H = 0.356–0.585). The majority of the genetic variation occurred within subpopulations. Approximately 8% and 4% of the variations were distributed between sampling year and location, respectively. Genetic distance (FST) results, using analysis of molecular variation (AMOVA), indicated that subpopulation pairing within isolates by year ranged from FST = 0.010 to 0.109, and the location subpopulation ranged from FST = 0.038 to 0.085. Bayesian clustering analyses of multiloci inferred two distinct clusters in all the subpopulations examined. This study indicates a relatively high degree of gene exchange between the different L. maculans isolates. Our results suggest that this can occur in the wide growing areas of canola fields in western Canada. This gene exchange produced different gene allele frequencies and divergence between populations.

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“…The virulent strain of blackleg (Leptosphaeria maculans) has been shown to be more prevalent in dockage than borne in the seeds (Fernando, Zhang, & Amarasinghe, 2016), so lower dockage rates could reduce (though not eliminate) the risk of spreading the infection. Article 5.6 requires Members to impose the least trade-restrictive measure necessary to achieve the desired level of protection.…”

Section: International Trade Rules and Dispute Resolution In The Wtomentioning

confidence: 99%

Blackleg or blackmail? Economics of the Canada–China canola trade dispute

Cardwell

Brewin

2019

Canadian J Agri Economics

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The Chinese government's recent decision to suspend the export licenses of two Canadian grain firms has garnered international attention. The dispute has been portrayed by some as a diplomatic dispute between two countries, and by others as a concern about plant health. We analyze the economics of the dispute, including a simple economic model of international trade in which a large-country importer imposes a targeted import ban on one large-country exporter. The model provides a framework for understanding the economic effects of a trade ban under various market conditions. We also discuss the legal framework and dispute settlement process that would be encountered if the disagreement proceeds to a formal dispute in the World Trade Organization.La récente décision du gouvernement chinois de suspendre les licences d'exportation de deux sociétés céréalières canadiennes a attiré l'attention de la communauté internationale. Le différend a été présenté par certains comme un différend diplomatique entre deux pays, et par d'autres comme une préoccupation phytosanitaire. Nous analysons les aspects économiques du différend, y compris un modèle économique simple de commerce international dans lequel un grand pays importateur impose une interdiction d'importation ciblée à un grand exportateur. Le modèle fournit un cadre permettant de comprendre les effets économiques d'une interdiction commerciale dans diverses conditions de marché. Nous discutons également du cadre juridique et du processus de règlement des différends qui seraient rencontrés si le désaccord devenait un différend formel au sein de l'Organisation mondiale du commerce. China on March 1, 2019. China issued several warnings about pests in canola 1 imports through the spring of 2019, and eventually suspended Richardson International's and Viterra's export licenses (AAFC, 2019). Richardson International and Viterra are two 1 We use the term canola to mean whole seeds ready for crushing. Some trade reports include trade in oil as a seed equivalent; we do not do use oil/seed equivalents here.

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Detection of Leptosphaeria maculans and Leptosphaeria biglobosa Causing Blackleg Disease in Canola from Canadian Canola Seed Lots and Dockage

Cited by 30 publications

References 30 publications

Insights into fighting against blackleg disease of Brassica napus in Canada

Insights into fighting against blackleg disease of Brassica napus in Canada

Distribution of mating‐type alleles and genetic variability in field populations of Leptosphaeria maculans in western Canada

Blackleg or blackmail? Economics of the Canada–China canola trade dispute

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