Plant Pathology (2021) 70, 1936-1944

Tamsal Murtza, Ming Pei You and Martin J. Barbetti (2021)
Temperature and relative humidity shape white leaf spot (Neopseudocercosporella capsellae) epidemic development in rapeseed (Brassica napus)
Plant Pathology 70 (8), 1936-1944
Abstract: Studies were undertaken to determine the combined environmental effects of two temperature regimes (14/11 °C, 17/14 °C day/night) and duration of postinoculation high humidity on progression of white leaf spot, caused by Neopseudocercosporella capsellae, in rapeseed (Brassica napus) at each of two different plant growth stages. Overall, percentage disease indices were significantly affected by temperature, high humidity duration, plant growth stage, and host cultivar (all p < 0.001). There were significant two-way interactions of temperature regime with plant age (p < 0.001) and with host cultivar (p < 0.01), and significant three-way interactions of high humidity duration with growth stage and host cultivar (p = 0.01) and with temperature and host cultivar (p = 0.03). At cotyledon stage, mean percentage cotyledon disease index was 38.2 at 17/14 °C day/night, and 33.1 at 14/11 °C. At fourth leaf stage, mean percentage leaf disease index was 32.0 at 14/11 °C but 17.5 at 17/14 °C. Disease severity increased with increasing duration of high humidity. Results explain why this disease is more prevalent and severe in Australia following longer durations of high humidity; why disease at cotyledon stage is largely independent of temperature if seasonal temperature ranges between 11 and 17 °C; and why more severe leaf infection (e.g., at fourth leaf stage) can be attributed to cooling winter conditions between autumn and winter. Studies suggest current/predicted climate changes across southern Australia of increasingly warmer autumn-winter temperatures and decreasing growing-season (May–August) precipitation will lessen severity of future epidemics.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Ming Pei You

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Neopseudocercosporella capsellae	Rape/canola (Brassica napus)	Australia (Western)