Effect of flooding on the survival of Leptosphaeria spp. in canola stubble

Abstract

This study used a versatile temperature-control device to assess the effect of temperature (12-40°C) and duration (2-12 weeks) of flooding on the survival of Leptosphaeria spp. in canola (Brassica napus) stubble. Canola basal stems with blackleg symptoms were submerged in water in small glass jars containing 20 cm 3 soil on a thermogradient plate capable of simultaneously maintaining up to 96 independent temperature regimes. Flooded stems were sampled at 2-week intervals, surface-sterilized, and incubated on V8-juice agar for 10 days to recover the pathogen. Flooding for 2 weeks substantially reduced pathogen recovery relative to non-flooded controls and the pathogen was not recovered after 6 weeks of flooding, irrespective of temperature. The pathogen was eliminated slightly more rapidly at flooding temperatures >20°C than at 12-16°C. There was no difference between Leptosphaeria maculans and L. biglobosa in their ability to survive flooding. Stem tissues degraded most rapidly during the first 2 weeks of flooding, corresponding to a quick decline in pathogen survival during the same period. These results indicate that a paddy rice crop following winter rapeseed may minimize the impact of blackleg by eradicating the inoculum of Leptosphaeria spp. in stubble.

Breakdown of Rlm3 resistance in the Brassica napus–Leptosphaeria maculans pathosystem in western Canada

“…Destruction of blackleg-infested stubbles by tillage has been recommended. A paddy rice crop following winter canola in some canola growing regions of China has been proven to be able to minimize the impact of inoculum in stubble (Peluola et al 2013). In Australia, new canola crops are recommended to be grown at least 500 meters from previous year's canola stubble (Marcroft et al 2003).…”

Crop Rotation With Cress Increases Cucumber Yields by Regulating the Composition of the Rhizosphere Soil Microbial Community

“…The diversity of soil microbial communities increases with increasing soil water content (SWC) in arid and semi-arid ecosystems, but SWC has no major effect on the diversity of soil microbial communities in wetland ecosystems (Cregger et al, 2012;Manzoni et al, 2012). Increasing evidences have fulfilled the gap between the short-and long-term flooding effects on soil microbial communities (Peluola et al, 2013). In environmental ecology, it is observed that flooding has important effects on the underground microbial environment (Shen et al, 2021), but the impact of varying degrees of flooding in agriculture ecology on the crop performance and microbial characteristics is still little known.…”

Detection of Leptosphaeria maculans and Leptosphaeria biglobosa Causing Blackleg Disease in Canola from Canadian Canola Seed Lots and Dockage

“…In China winter oilseed rape is often followed by several weeks of flooding with a paddy rice crop [ 14 ]. It has been reported that flooding can rapidly reduce the survival of the Blackleg pathogen in canola stubble [ 15 ]. L. maculans is considered a global invasive species, it has recently spread across Canada (1975–1998), from the USA into Mexico (2001) and eastwards across Europe into Poland (1994–2007), where only the less damaging L. biglobosa was previously present [ 1 ].…”