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A survey was conducted in southern Alberta, Canada, to collect Fusarium stalk rot and Fusarium head blight (FHB) disease samples from corn and wheat fields, respectively, with an aim to understand the diversity in the population of Fusarium graminearum. From 77 wheat and 80 corn samples, 79 isolates of F. graminearum were obtained. These 79 isolates were evaluated for their growth rate, sporulation ability, pathogenicity and trichothecene genotype. Eighty-two percent of the isolates were recovered from corn, which suggests corn residue may be better suited than wheat for perpetuating the FHB pathogen. Three genotypes with potential of producing 3-ADON, 15-ADON and NIV were present in the population, and among them, 15-ADON producing genotype was predominant, and 3-ADON genotype produced more spores than the 15-ADON genotype. The proportion of 3-ADON genotype is increasing overtime in Alberta. The impact of increasing population of 3-ADON genotype is worthy of to be monitored for the management of FHB. There were variations in the population of F. graminearum isolates for growth rate, sporulation and pathogenicity but revealed no association among the parameters suggesting other factors like host susceptibility and environment play a significant role in the development of FHB. [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]

Clubroot, caused by Plasmodiophora brassicae , is an important disease on canola in Alberta, Canada. The pathogen is grouped into pathotypes according to their virulence reaction on differential hosts. Multiple pathotypes or strains are known exist in one field, one plant, or even one gall. This study was conducted with the objective of testing the prevalence of the coexistence of multiple strains in a single gall. In all, 79 canola clubroot galls were collected from 22 fields across Northern Alberta in 2018. Genomic DNA extracted from these single galls was analyzed using RNase H-dependent PCR (rhPCR). The rhPCR primers were designed to amplify a partial sequence of a dimorphic gene, with one primer pair specific to one sequence and the other primer pair specific to the alternative sequence. The amplification of both sequences from DNA obtained from a single gall would indicate that it contains two different P. brassicae strains. The rhPCR analyses indicated that the P. brassicae populations in 50 of the 79 galls consisted of more than one strain. This result emphasizes the need for cautious interpretation of results when a single-gall population is subject to pathotyping or being used as inoculum in plant pathology research. It also confirms that the maintenance of pathotype diversity within single root galls is a common occurrence which has implications for the durability, and stewardship, of single-gene host resistance.