First, populations maintain high pathotypic diversity, which can rapidly shift to become virulent on previously resistant hosts ( Strelkov et al. Research on methods for avoidance, containment, and management of clubroot have revealed a great deal about this disease in large-scale field crop production systems on the Canadian Prairies, but despite these efforts, the pathogen continues to spread to new fields and overcome the genetic resistances deployed in modern canola cultivars ( Gossen et al. Additionally, many Alberta fields are very conducive to clubroot disease initiation and symptom development because of their high-moisture and low-pH soil characteristics. Its transition into canola fields was an important development because of the potential for rapid buildup of resting spores in large fields growing susceptible canola cultivars, the significant economic impact because of yield loss, and the large proportion of agricultural fields (∼7 million acres or ∼30%) used for canola production across the province. The report of clubroot on canola came from the Province of Alberta, which before 2003, had only rarely reported clubroot symptoms on vegetables in backyard gardens and market gardens ( Howard et al. The impact of clubroot ( Plasmodiophora brassicae Woronin) on brassica crops in Canada began to increase dramatically after the first report of the disease on canola ( Brassica napus L) in 2003 by Tewari et al. Additionally, it was equivalent to the qPCR method for differentiating viable and nonviable spores ( R 2 = 99.84 P ≤ 0.001) and confirmed in canola infection bioassays. The results demonstrated that the modified Evans blue staining method improved the accuracy and consistency of measurement of P. The accuracy of the modified method to discriminate viable and nonviable spores was evaluated in repeated experiments and by comparing the staining data with those derived from inoculation assays and propidium monoazide quantitative PCR (qPCR). Extending staining times significantly increased the numbers of stained resting spores up to 7 h, after which the numbers of stained spores did not change significantly ( R 2 = 96.88 P ≤ 0.001). brassicae resting spores after heat treatment at various combinations of temperature and time.

In this study, we modified the Evans blue method by increasing the staining time to 8 h or more and evaluated P. brassicae resting spores have not provided accurate or consistent results. Some previously published protocols using Evans blue to stain P. Evans blue is one example of a vital stain that has been reported to differentially stain viable and nonviable resting spores. brassicae resting spores can provide useful information regarding spore longevity, inoculum potential, or the efficacy of antimicrobial treatments. The use of vital stains to determine the viability of P. Clubroot caused by Plasmodiophora brassicae is an important disease of brassica crops.

Spore stain