Premium
Temperature and relative humidity shape white leaf spot ( Neopseudocercosporella capsellae ) epidemic development in rapeseed ( Brassica napus )
Author(s) -
Murtza Tamsal,
You Ming Pei,
Barbetti Martin J.
Publication year - 2021
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/ppa.13437
Subject(s) - cotyledon , brassica , cultivar , biology , rapeseed , relative humidity , humidity , horticulture , agronomy , botany , zoology , physics , thermodynamics
Studies were undertaken to determine the combined environmental effects of two temperature regimes (14/11 ℃, 17/14 ℃ 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 ℃ day/night, and 33.1 at 14/11 ℃. At fourth leaf stage, mean percentage leaf disease index was 32.0 at 14/11 ℃ but 17.5 at 17/14 ℃. 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 ℃; 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.