Fungal plant pathogens infecting barley and wheat seed from Alberta, 1995-1997.
From 1995 to 1997, spikes were collected from a total of 160 barley and 188 wheat fields from the Peace River region to the Three Hills area of Alberta, Canada. After threshing, 100 seeds from each field were surface sterilized, incubated on potato dextrose agar, and examined for the presence of the following pathogens: Fusarium graminearum [Gibberella zeae], other Fusarium spp., Cochliobolus sativus, Pyrenophora tritici-repentis, Pyrenophora graminea, Pyrenophora teres, and Stagonospora nodorum. Fusarium graminearum was not detected in any seed samples. The most common Fusarium species isolated was Fusarium avenaceum [Gibberella avenacea]. Maximum seed infection levels with F. avenaceum in a single field were 51 and 37% for barley and wheat, respectively. Substantial levels of seedborne P. teres were found in barley with maximum infection levels of 82, 81, and 89% in 1995, 1996, and 1997, respectively. Stagonospora nodorum [Phaeosphaeria nodorum] was also commonly found in both barley and wheat seed with maximum infection levels of 61 and 54%, respectively. Pyrenophora tritici-repentis, P. graminea, and C. sativus were generally present at low levels.