Survival of leaf spot pathogens on crop residues of wheat and barley in Saskatchewan.

Pycnidia of Stagonospora nodorum, and pseudothecia of Phaeosphaeria nodorum and Pyrenophora triticirepentis occurred in greater numbers after one overwintering period on residues of wheat and barley stored on the surface of the soil than on residues from the previous fall. Conidial numbers of Bipolaris sorokiniana and Drechslera teres on residues of wheat and barley, and pseudothecia of Pyrenophora teres on residues of barley decreased over one winter but these pathogens continued to sporulate at low levels after two winters. With residue from the soil surface, Drechslera teres and B. sorokiniana conidia occurred in greater numbers on lower parts of the plants. Drechslera teres occurred primarily on leaf and sheath areas and B. sorokiniana, on sheath and stem areas, while P. teres sporulated mainly on stems. Numbers of conidia of D. teres may have declined because the pathogen occurred mainly on leaves, which disintegrated after one winter. The wheat pathogen Stagonospora nodorum was able to sporulate on ...