Genotyping by sequencing suggests overwintering of Peronospora destructor in southwestern Québec, Canada.

Several Peronospora species are carried by wind over short and long distances, from warmer climates where they survive on living plants to cooler climates. In eastern Canada, this annual flow of sporangia was thought to be the main source of Peronospora destructor responsible for onion downy mildew. However, the results of a recent study showed that the increasing frequency of onion downy mildew epidemics in eastern Canada is associated with warmer autumns, milder winters, and previous year disease severity, suggesting overwintering of the inoculum in an area where the pathogen is not known to be endogenous.

Detection and Quantification of and AG1-IB Causing the Bottom Rot of Lettuce in Tissues and Soils by Multiplex qPCR.

In the muck soil region of southwestern Quebec, vegetable growers are threatened by several soilborne diseases, particularly the bottom rot of lettuce caused by the fungus . The particularly warm temperature of the few last seasons was marked by an increase in disease severity, and the associated yield losses were significant for Quebec lettuce growers. In the absence of registered fungicides and resistant cultivars, the management of -induced diseases in lettuce is based on good agricultural practices, which require detailed knowledge of the pathogen.

Evidence for Differences in the Temporal Progress of Clades and Airborne Inoculum Monitored in Vineyards in Eastern Canada Using a Specific Multiplex Quantitative PCR Assay.

Four clades of isolated from wild and cultivated species were described in 2013. Only clades and have been detected in eastern Canada. To increase our understanding of the epidemiology of these clades of , airborne sporangia were monitored with spore samplers at two experimental vineyards from 2015 to 2018 and at 11, 14, and 15 commercial vineyards in 2016, 2017, and 2018, respectively.