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Cannabis (Cannabis sativa L., marijuana) plants grown at indoor and outdoor production sites in British Columbia (BC) and Ontario with stem canker symptoms were sampled and affected tissues were surface-sterilized and plated onto potato dextrose agar. Isolates were identified by colony and spore morphology as well as PCR amplification and sequencing of the ITS1-ITS2 rDNA, beta-tubulin, and actin gene regions. The most frequently isolated fungi were Alternaria alternata, Neofusicoccum parvum, and Lasiodiplodia theobromae. In addition, A. alternata was recovered from cannabis inflorescences in BC as well as surface-sterilized hemp seed. Stemphylium vesicarium was isolated from hemp seeds for the first time. The pathogenicity of all these fungi to cannabis plants was confirmed by inoculation of leaves, stems, buds, rooted cuttings and mature plants. Disease ratings varied depending on both tissue type and pathogen. Both L. theobromae and N. parvum produced extensive stem cankers on mature cannabis plants as well as extensive lesions on leaves. All pathogens showed optimal colony growth in culture at 25–30°C. A comparison of the susceptibility of five cannabis genotypes to foliar infection by N. parvum indicated there were significant differences (p < 0.05) in lesion size, with some genotypes showing high susceptibility and others showing resistance. This is the first report of L. theobromae, N. parvum, A. alternata, and S. vesicarium causing stem canker and leaf spot symptoms on cannabis in Canada. The recovery of these fungi adds to the growing list of pathogens that cause infection and loss of quality in cannabis production. [ABSTRACT FROM AUTHOR]

Field surveys indicate blackleg of canola has increased in western Canada since 2010. Earlier studies showed changes in the pathogen (Leptosphaeria maculans (Sowerby) P.Karst.; Lm) population between 2007 and 2010–2011. In this study, Lm isolates were collected from trap plots (591) and/or commercial fields (372) on the prairies between 2012 and 2014, and tested for the profile of avirulence (Av) genes on a set of host differentials for 10 Lm Av alleles. Up to 35 'Westar' trap plots were set up each year, and commercial fields were surveyed in the same area in 2012 and 2013. A similar trend was observed for Av profile between the two Lm populations; Av1, Av3, Av9 and AvLep2 were at low or very low levels, while Av2, Av4, Av6 and Av7 were present in >60% of the isolates. A total of 82 races were identified in these Lm populations, suggesting a greater diversity than those reported elsewhere. Margalef and Simpson indices also confirmed the greater genetic diversity in Lm. In fact, for each known R gene, there is at least one virulent race already existing in the Lm population. The races carrying Av2, Av4, Av6 or Av7 accounted for >70% of the Lm population, indicating that an R gene corresponding to any of these Av alleles may be effective against blackleg on the prairies. However, Av results alone appeared insufficient for explaining different levels of blackleg observed in canola fields; additional factors, possibly including crop rotation and local weather, may also play a role. [ABSTRACT FROM AUTHOR]

Blackleg, caused by Leptosphaeria maculans, is a serious disease on canola or rapeseed in Canada, Australia and Europe. Disease levels have increased in western Canada recently and additional tools are needed to improve blackleg management. Seed treatment can be a cost-effective approach against blackleg, but there is currently no registered seed-treatment product targeting aboveground blackleg infection. In this study, a range of fungicides was evaluated for control of cotyledon infection by L. maculans and blackleg of canola. Under controlled environmental conditions, fluopyram showed greater efficacy than fluquinconazole (used against blackleg in Australia) in limiting cotyledon infection, while Prosper® EverGol and Helix® Vibrance (industry standards) were ineffective. Fluopyram at a rate of 30–150 g/100 kg seed generally inhibited cotyledon infection and this efficacy was not affected by delayed soil moisture for 3 weeks after planting. This indicates that the efficacy will unlikely be affected by a slight delay in germination due to a soil moisture deficit after seeding. In addition to typical mechanisms of succinate dehydrogenase inhibitor fungicides, fluopyram also induced expression of the indicator gene coding PR-1 proteins substantially, indicating the potential for inducing disease resistance. In field trials at 75 and 150 g/100 kg seed, fluopyram reduced the infection on cotyledons resulting from pricking inoculation on both susceptible and resistant canola cultivars, potentially limiting the infection into the stem. These seed treatment rates reduced the disease severity index (DSI) substantially on the susceptible cultivar, while DSI was low on a resistant cultivar with or without fluopyram treatment. [ABSTRACT FROM AUTHOR]

The article presents the etiologic factor of severe stem canker on greenhouse eggplant, incited by Fusarium solani, in the greenhouse vegetable industry in Leamington, Ontario. The said disease was diagnosed based on symptoms, reisolation of the pathogen, completion of Koch's postulates, fungal morphology, and cultural characteristics. Based on the study, wounding of the stem, as well as roots, had caused greater incidence and severity of canker development.