Diseases

Rapeseed Leaf Spots

Brassica napus var. napus

A group of rapeseed diseases manifested as necrotic spots of various etiologies, including Alternaria blight, phoma stem canker, cylindrosporiosis, and black rot.

In the reference 31 varieties crop Rapeseed, where this is mentioned in the description.

Alternaria blight of rapeseed, caused by the fungi Alternaria brassicae and A. brassicicola, is characterized by circular spots with concentric zonation and a black velvety coating. Phoma leaf spot, caused by Leptosphaeria maculans and L. biglobosa, manifests as dry gray spots with pycnidia and potential necrosis of the root collar. Resistance to phoma is controlled by Rlm genes, which interact with the pathogen according to the gene-for-gene model.

White leaf spot, or cylindrosporiosis, is caused by the fungus Cylindrosporium concentricum and appears as whitish or gray spots with a loose coating. Bacterial leaf spot, caused by Xanthomonas campestris pv. campestris, is distinguished by V-shaped necrotic spots with a chlorotic halo and a water-soaked appearance of the tissues. For Alternaria and bacterial pathogens, the presence of virulent races has been described, which necessitates consideration of regional specificity when selecting resistant varieties.

General information about the subject — on the page Leaf spot diseases.

Sources8

Varieties of Rapeseed mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.