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Root rot disease poses a significant threat to canola (Brassica napus), underscoring the need for a comprehensive understanding of its causal agents for more effective disease mitigation. The composition and diversity of fungal pathogens associated with root rot of canola in Alberta, Canada, were evaluated from plant tissue samples collected in 2021 and 2022. The study revealed Fusarium spp. as the predominant pathogens found in almost all surveyed fields. Fusarium avenaceum, F. redolens, and F. solani were among the most frequently recovered species. Greenhouse trials confirmed their pathogenicity, with F. avenaceum and F. sporotrichioides found to be particularly aggressive. Additionally, F. sporotrichioides and F. commune were identified for the first time as canola root rot pathogens. Inoculation with isolates of most species resulted in significant reductions in seedling emergence, plant height, and shoot and root dry weights. Analysis of translation elongation factor 1-α (TEF-1α) and internal transcribed spacer (ITS) sequences confirmed the identity of the Fusarium spp., while concatenating the ITS and TEF-1α sequences enabled improved species differentiation. Geographic and year effects did not influence fungal diversity or aggressiveness, as determined by principal component analysis. This study emphasized the high diversity and impact of Fusarium spp. in causing canola root rot. [ABSTRACT FROM AUTHOR]

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Abstract Soybean (Glycine max (L.) Merr.) has been a commercial oilseed crop in Canada since the 1920s. The production of soybean rapidly increased from 2004 to 2016 in Alberta and Manitoba. Root rot disease caused by the oomycete genus Pythium was observed from 105 fields in 2015 and 2016 in southern Alberta and Manitoba. In the present study, a total of 97 isolates of Pythium were recovered from the root tissues of soybean seedling collected from those fields. Identification of the Pythium species was achieved by examining their morphological features and sequences analysis of internal transcribed spacers (ITS) and cytochrome oxidase subunit 2 gene (Cox II). Nine species of Pythium were identified, with Pythium violae as the predominant species (27 out of 97, 27.8%), followed by P. intermedium (21), P. irregulare (16), P. sylvaticum (12), P. recalcitrans (8), P. ultimum (8), P. heterothallicum (3), P. conidiophorum (1) and P. macrosporum (1). This is the first report of P. conidiophorum , P. recalcitrans and P. violae on soybean in Canada. All the Pythium isolates except three isolates (S2d of P. violae , S29a and S29b of P. heterothallicum) were highly virulent on soybean, causing root rot disease symptoms. Highlights • Obtained 97 Pythium isolates from soybean in Alberta and Manitoba from 2015 to 2016. • Pythium violae was predominant within nine identified Pythium species. • First report of P. conidiophorum , P. recalcitrans and P. violae in soybean in Canada. • All of the Pythium isolates were able to infect soybean with varied aggressiveness. [ABSTRACT FROM AUTHOR]

Soybean ( Glycine max (L.) Merr.) has excellent potential as an alternative crop to canola in southern Alberta farming systems. However, soybean is susceptible to Fusarium root rot, which usually results in the occurrence of dead or dying plants in mid-to-late summer and severe reductions in yield. A total of 102 isolates identified as Fusarium were recovered from diseased soybean root samples collected from central and southern Alberta from 2011 to 2013. Ten species of Fusarium were identified, with F. acuminatum as the predominant species (31 out of 102 isolates, 30.39%), followed by F. equiseti (16.67%), F. culmorum (13.73%), F. avenaceum (10.78%), F. oxysporum (8.82%), F. redolens (7.84%), F. torulosum (4.90%), F. tricinctum (2.94%), F. commune (1.96%) and F. proliferatum (0.98%). This is the first report of F. commune , F. redolens and F. torulosum causing root rot in soybean in Canada. Phylogenetic analyses based on sequence data from the translation elongation factor 1-α (EF-1α) and the internal transcribed spacer (ITS) region were used to evaluate genetic variation and, in conjunction with morphological characters, for species identification. All of the Fusarium isolates were able to infect soybean, although some exhibited varying levels of aggressiveness. [ABSTRACT FROM AUTHOR]

Abstract: Ascochyta blight, caused by a complex of Mycosphaerella pinodes, Phoma pinodella, Ascochyta pisi, and/or Phoma koolunga, is a devastating disease of field pea. In order to understand the composition of fungi associated with ascochyta blight in Alberta, Canada, a total of 157 single-pycnidiospore fungal isolates were obtained from diseased pea samples collected from central and northern Alberta in 2011. These isolates were characterized for species identity, aggressiveness, DNA sequence variation in the internal transcribed spacer (ITS) region, and random amplification of polymorphic DNA (RAPD) patterns. The ITS sequences obtained from 142 fungal isolates were all identical to the ITS sequences from M. pinodes and/or P. pinodella. Inoculation of the 157 isolates on a susceptible pea cultivar Midas indicated that most of the isolates were moderately to highly aggressive. Phylogenetic analysis based on the RAPD data revealed two main groups and six sub-groups, with one main group comprising 78% of the 157 isolates. Distinct RAPD patterns were associated with isolates from particular geographic locations, but were not generally associated with isolate aggressiveness. [Copyright &y& Elsevier]

Abstract: Downy mildew, caused by Peronospora viciae f. sp. pisi, has emerged as a destructive disease of field pea in central Alberta, Canada. The objectives of the current study were to identify the predominant P. viciae pathotypes in Alberta and to assess genetic diversity in regional populations of the pathogen. Three pathotypes (UKP1, UKP2 and UKP11) were identified when nine populations of P. viciae were tested on a host differential set, with pathotype UKP1 being predominant. A collection of 30 P. viciae isolates clustered into three main groups when subjected to random amplified polymorphic DNA (RAPD) marker analysis. Comparison of the internal transcribed spacer (ITS) and 5.8S ribosomal RNA (rRNA) gene sequences revealed a high degree of homology among the isolates, suggesting a common origin. This is the first report on the pathotype composition and genetic diversity of P. viciae in western Canada. [Copyright &y& Elsevier]

Queen Anne's lace and poker statice plants were found with a yellows-type disease with typical phytoplasma symptoms in an experimental farm near Brooks, Alberta in 1996. Phytoplasma bodies were detected by transmission electron microscopy in phloem cells of symptomatic plants, but not in healthy plants. The presence of a phytoplasma was confirmed by analysis with the polymerase chain reaction. Using a pair of universal primer sequences derived from phytoplasma 16S rRNA, an amplified product of the expected size (1.2 kb) was observed in samples from infected plants, but not in asymptomatic plants. Sequence analysis of the PCR products from the 16S/23S rDNA intergenic spacer region indicated that the two phytoplasma isolates in Queen Anne's lace and poker statice are genetically closely related to the western aster yellows phytoplasma.