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Journal articles
Methods for Sampling and Assessment in Relation to the Spatial Pattern of Phoma Stem Canker (Leptosphaeria maculans) in Oilseed Rape
Abstract : A sound assessment of phoma stem canker symptoms is needed to develop epidemiological, agronomical and physiological studies on the pathosystem. A specific analysis was therefore carried out to: (i) compare four methods of crown canker assessment; (ii) test the among and within assessor repeatability of one of the methods compared; (iii) characterise the spatial pattern of the disease; and (iv) define the sample size required to achieve a given level of disease assessment precision. The methods compared examined the symptoms with different procedures and graded the plants observed into six severity classes. A disease index (DI) summarised the severity distribution observed. Examination of crown cross-sections was the most precise method for assessing crown cankers. The method was repeatable, though an 'assessor effect' was apparent. The disease generally had a random pattern although significant spatial correlations were detected for four out of the fifteen plots studied at the scales examined. A relationship between the coefficient of variation of the DI and the sample size was established, evaluated with experimental field data and exemplified for typical severity distributions.
Cited literature [10 references]
https://hal-agroparistech.archives-ouvertes.fr/hal-01363609
Contributor : Thierry Doré <>
Submitted on : Monday, October 7, 2019 - 6:24:51 PM
Last modification on : Monday, July 6, 2020 - 3:38:19 PM
Contributor : Thierry Doré <>
Submitted on : Monday, October 7, 2019 - 6:24:51 PM
Last modification on : Monday, July 6, 2020 - 3:38:19 PM
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Aubertot et al EJPP 2004.pdf
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