Vertical distribution of Plasmodiophora brassicae resting spores in soil and the effect of weather conditions on clubroot development
Canola (Brassica napus L.) is a high-value agricultural commodity in Canada. Plasmodiophora brassicae Woronin, the causative agent of clubroot, can cause substantial decreases in yield of susceptible crucifer species. To help understand and possibly model the epidemiology of disease, the influence of weather on development of clubroot was examined. Soil moisture and air temperature were found to be important variables affecting disease development. The etiology of disease is also influenced by the presence of resting spores in infested soils. A qPCR method was developed and assessed to quantify the prevalence and vertical distribution of these resting spores in the soil profile. Management techniques targeting resting spores should be applied to depths of the deepest brassica roots for complete disease suppression since resting spores were found in levels high enough to cause severe disease at the deepest sampling depth of 53 cm.