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Even for experienced raters, a training session is highly recommended before rating real sampled plants! As is the case with many other diseases, a rater's bias effect exists when assessing the severity of phoma stem canker. In order to limit this effect, severity assessment training can be standardised to limit discrepancies among different raters. This is the main objective of PHOMADIDACTE. The basic principle of the program consists of displaying pictures of cankered cross-sections of oilseed rape that are to be assessed by a rater. These pictures were previously rated by a panel of eight experts from four different research or extension units (2 INRA units, 1 CETIOM unit, 1 GEVES unit). The two sets of assessments (the user s and the experts) are then compared. At the end of a training session, the agreement between the experts rating and the users will be displayed.

The work was supported by the CASDAR project AO 2005 number 391 Mise au point et utilisation d’outils de biovigilance et de gestion durable des résistances variétales aux pathogènes (Creation and use of tools for biovigilance and sustainable management of varietal resistances of pathogens), coordinated by the CETIOM in the framework of the UMT Pivert.

Rating scale

As a user of the training program, you will be shown photos of cross-sections of oilseed rape. You will have to assign them to one of 6 severity classes, depending on the percentage of cross-section with lesions caused by Leptosphaeria maculans.

Severity class	Description	Example 1 (click on the picture to magnify it)	Example 2 (click on the picture to magnify it)
1	Healthy plant, no visible lesions.
2	0-25% of discoloured cross-section.
3	25-50% of discoloured cross-section.
4	50-75% of discoloured cross-section.
5	75-100% of discoloured cross-section.
6	Section without any living tissue.

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