Background Plasmodiophora brassicae is the causal agent of clubroot disease of cruciferous plants and one of the biggest threats to the rapeseed (Brassica napus) and brassica vegetable industry worldwide. Disease symptoms In the advanced stages of clubroot disease wilting, stunting, yellowing, and redness are visible in the shoots. However, the typical symptoms of the disease are the presence of club‐shaped galls in the roots of susceptible hosts that block the absorption of water and nutrients. Host range Members of the family Brassicaceae are the primary host of the pathogen, although some members of the family, such as Bunias orientalis, Coronopus squamatus, and Raphanus sativus, have been identified as being consistently resistant to P. brassicae isolates with variable virulence profile. Taxonomy Class: Phytomyxea; Order: Plasmodiophorales; Family: Plasmodiophoraceae; Genus: Plasmodiophora; Species: Plasmodiophora brassicae (Woronin, 1877). Distribution Clubroot disease is spread worldwide, with reports from all continents except Antarctica. To date, clubroot disease has been reported in more than 80 countries. Pathotyping Based on its virulence on different hosts, P. brassicae is classified into pathotypes or races. Five main pathotyping systems have been developed to understand the relationship between P. brassicae and its hosts. Nowadays, the Canadian clubroot differential is extensively used in Canada and has so far identified 36 different pathotypes based on the response of a set of 13 hosts. Effectors and resistance After the identification and characterization of the clubroot pathogen SABATH‐type methyltransferase PbBSMT, several other effectors have been characterized. However, no avirulence gene is known, hindering the functional characterization of the five intercellular nucleotide‐binding (NB) site leucine‐rich‐repeat (LRR) receptors (NLRs) clubroot resistance genes validated to date. Important Link Canola Council of Canada is constantly updating information about clubroot and P. brassicae as part of their Canola Encyclopedia: https://www.canolacouncil.org/canola-encyclopedia/diseases/clubroot/. Phytosanitary categorization PLADBR: EPPO A2 list; Annex designation 9E.

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Blackleg, caused by Pectobacterium spp. and Dickeya spp., is an important disease of potatoes. During the period from November 20 and March 2021, stems of potato plants showing necrosis and rot symptoms, and chlorotic leaves, were collected from commercial production areas of the Mayabeque province of Cuba (Fig. 1A). After disinfestation of affected stems, small fragments of the stem were cut and macerated in a sterile 0.85% NaCl solution. Serial dilutions of bacterial suspension were prepared and streaked onto nutrient agar in Petri plates. Two colonies per sample showing the characteristic of “fried egg” were selected for further investigation, and an isolated was selected and named D7. The isolated bacterium was rod shaped, gram-negative, motile, oxidase and indole production negative, with anaerobic growth, and able to use lactose as carbon source in Mac Conkey Agar medium. One colony of the isolate D7 was selected and multiplied. Total DNA of the bacteria cells was extracted and used to amplify the genes pelADE (Nassar et al., 1996) and gapA (Cigna et al., 2017), to differentiate Dickeya from Pectobacterium. The sequence obtained showed 99.75% and 99.88% nucleotide identity with Dickeya solani for pelADE (Genbank accession number ON644347) and gapA (Genbank accession number ON644346), respectively. To confirm the pathogenicity of the isolate D7, four 15-day-old potato plants, including two plants of each ‘Otolia’ and ‘Naima’ potatoes were inoculated with a bacterial suspension of the isolate D7 (108 CFU/ml) in sterile water by stabbing. Control plants were stabbed with sterile water. Inoculated plants were maintained at 28°C, relative humidity of about 90%, and at 12 h light/12 h dark, as described by (Chen et al. 2014). After 3 to 5 days, typical blackleg disease symptoms (water-soaked lesions and necrosis) developed at the inoculated areas of plants (Fig. 1B). No symptom was observed in the control plants. Bacterium was re-isolated from symptomatic plants and the isolates had the same cultural, physiological, and biochemical characteristics to the isolate D7. To our knowledge, this is the first report of D. solani causing blackleg in potato fields in Cuba. Further studies to determine the spread of this pathogen in potato producing areas in Cuba is underway.