Temperature and plant age drive downy mildew disease epidemics on oilseed Brassica napus and B. juncea

Geographic location and year determine virulence, and year determines genetic change, in populations of Neopseudocercosporella capsellae

“…Manning & Tiedemann, ; Rosenzweig et al , ). Other Australian studies on rapeseed have demonstrated more severe disease under warmer rather than cooler temperatures, including for H. brassicae (Mohammed et al , ), Erysiphe cruciferarum (Uloth et al , ) and L. maculans (Barbetti, ; Li et al , ). The present study with isolates collected in 2016 across three states of Australia highlights distinct overall differences in terms of virulence between the states.…”

Molecular characterization of disease resistance in Brassica juncea – The current status and the way forward

“…Such impacts include changes of temperature, rainfall, and humidity, the main drivers of plant disease severity. For example, the expression of some Brassica resistance genes against pathogens are temperature dependent, including blackleg (Li et al, 2006b), TuMV (Nyalugwe et al, 2014), Sclerotinia (Uloth et al, 2015c), powdery mildew (Uloth et al, 2018), and downy mildew epidemics in B. juncea and B. napus (Mohammed et al, 2018a). Li et al (2006a) argued that resistance against sclerotinia stem rot may not be currently necessary for B. juncea due to its optimal cultivation in low rainfall regions, where the conditions are less favourable for this disease.…”

“…In Australia, blackleg and sclerotinia have been identified as the most destructive diseases for oilseed-and vegetable-type mustards (Murray and Brennan, 2012;Uloth et al, 2013Uloth et al, , 2014Uloth et al, , 2015aUloth et al, , 2015bVan de Wouw et al, 2016). However, there are several other diseases also identified as important in Australia, including TYV, downy mildew, white leaf spot, alternaria blight, bacterial leaf blight, and powdery mildew (Li et al, 2006a(Li et al, , 2007(Li et al, , 2008a(Li et al, , 2009bEshraghi et al, 2007;Murray and Brennan, 2012;Gunasinghe et al, 2014;Van de Wouw et al, 2016;Mohammed et al, 2017Mohammed et al, , 2018aMohammed et al, , 2018bMohammed et al, , 2019Al-lami et al, 2019aAl-lami et al, , 2019bAl-lami et al, , 2019cGuerret et al, 2017;Uloth et al, 2016Uloth et al, , 2018Murtza et al, 2019).…”

“…B. juncea cultivars resistant to both white rust and downy mildew are an important requirement in many regions where both pathogens coexist (e.g., India and Australia). In Australia, downy mildew is a major disease affecting oilseed and vegetable brassicas, particularly across southern and western Australian regions (Mohammed et al, 2018a(Mohammed et al, , 2018b. Although H. brassicae has been present on Australian B. napus and B. juncea crops for decades (Barbetti and Khangura, 2000), it shows increasing severity and threat to commercial brassica crops in some regions of Australia, particularly since 1998 (Barbetti and Khangura, 2000).…”

“…juncea cultivars resistant to both white rust and downy mildew are an important requirement in many regions where both pathogens coexist (e.g., India and Australia). In Australia, downy mildew is a major disease affecting oilseed and vegetable brassicas, particularly across southern and western Australian regions (Mohammed et al, 2018a, 2018b). Although H .…”