Diseases

Leaf blotch — soft wheat

Triticum aestivum L.

A group of fungal diseases of wheat, including Septoria tritici blotch, tan spot, and spot blotch. The diseases have similar symptoms but differ in pathogens and genetic mechanisms of interaction with the host plant.

In the reference 239 varieties crop Bread wheat, where this is mentioned in the description.

The most common pathogens of leaf blotch are Zymoseptoria tritici (Septoria tritici blotch), manifested by black pycnidia in light-colored spots; Pyrenophora tritici-repentis (tan spot), characterized by spots with a chlorotic halo; and Bipolaris sorokiniana (spot blotch), which forms brown spots with a dark border.

The genetic control of resistance involves specific loci. For Septoria tritici blotch, genes of the Stb series (e.g., Stb16q, Stb7) have been identified. Resistance to tan spot is closely linked to the Tsn1 locus: the presence of the dominant allele makes the variety susceptible to the ToxA toxin produced by the pathogen, which exacerbates necrotic lesions.

At least eight races have been described for tan spot, classified by virulence on sets of differential varieties. Physiological leaf spot, which arises as a reaction to stress factors or phytotoxicity of chemicals and has no genetic resistance nomenclature, should be distinguished from infectious leaf blotches.

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

Sources8

Varieties of Bread wheat 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.