Effects of temperature and rainfall on date of release of ascospores of Leptosphaeria maculans (phoma stem canker) from winter oilseed rape (Brassica napus) debris in the UK

• Published in: Annals of applied biology Vol. 151; no. 1; pp. 99 - 111
• Main Authors: Huang, Y.J, Liu, Z, West, J.S, Todd, A.D, Hall, A.M, Fitt, B.D.L
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.08.2007; Blackwell Publishing Ltd; Blackwell
• Subjects: Biological and medical sciences; Brassica napus; Climate; disease forecasting; empirical model; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Leptosphaeria maculans; Phoma; Phoma lingam; Phytopathology. Animal pests. Plant and forest protection; pseudothecial maturation; United Kingdom; Europe; Western Europe; Climate; Plant pathogen; Brassica napus var. oleifera; Disease; Temperature effect; Environmental factor; Physical environment; Temperate zone; Spores; Stem; Fungi; Rain; Cruciferae; Dicotyledones; Angiospermae; pseudothecial maturation; Ascomycetes; Fungi Imperfecti; Debris; Release; Thallophyta; Plant production; Meteorological phenomenon; Ascospore; disease forecasting; Empirical model; Forecasting; Ripening; Phoma lingam; Leptosphaeria maculans; Vegetative apparatus; Spermatophyta; Atmospheric precipitation; Oil plant (vegetal)
• ISSN: 0003-4746; 1744-7348; 1744-1348
• DOI: 10.1111/j.1744-7348.2007.00157.x

Data from a controlled environment experiment investigating effects of temperature on maturation of Leptosphaeria maculans pseudothecia were used to derive equations describing the times until 30% or 50% of pseudothecia were mature as a function of temperature. A wetness sensor was developed to estimate the oilseed rape debris wetness and operated with debris exposed in natural conditions in 2000 and 2001. The maturation of L. maculans pseudothecia on debris and concentrations of airborne L. maculans ascospores were observed from 1999 to 2004. There were considerable differences between years, with the first mature pseudothecia observed in September in most years. There were linear relationships between the first date when 10% of maximum ascospore release was observed and the dates when 30% or 50% of pseudothecia were mature. By summing the daily temperature-dependent rate of pseudothecial maturation for days after 1 August with rainfall >0.5 mm, the dates when 30% or 50% of pseudothecia were mature were predicted. There was good agreement between predicted and observed dates when 30% or 50% of pseudothecia were mature. These equations for predicting the timing of L. maculans ascospore release could be incorporated into schemes for forecasting, in autumn, the severity of phoma stem canker epidemics in the following spring/summer in the UK.