Detection and quantification of Leptosphaeria maculans in the leaf petiole of Brassica napus

In controlled environment experiments winter oilseed rape (Brassica napus) cultivars Canberra and Courage did not differ significantly in leaf lesion size and systemic growth in petioles, measured after inoculation of leaves with conidia of Leptosphaeria maculans isolate ME24 (transformed to express green fluorescent protein). In field experiments (2003/2004) quantification of L. maculans within petioles of six doubled haploid (DH) lines of oilseed rape derived from Canberra x Courage showed differences in the number of colony forming units obtained from maceration of petiole parts. Differences between lines did not relate to differences in stem canker severity at harvest