Pyrenophora tritici-repentis, P. bromi,andLeptosphaeria nodorumonBromus inermisin the Northern Great Plains

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Abstract
A study was undertaken to determine the distribution of Pyrenophora tritici-repentis and Leptosphaeria nodorum, two foliar pathogens of wheat, on smooth bromegrass (Bromus inermis), an alternative host. Smooth bromegrass was selected for evaluation as a host for foliar pathogens of wheat because it is widespread along roadways and windbreaks near fields of cereal crops. From 1981 through 1984, leaf samples were collected in the northern Great Plains, including 125 in North Dakota, 32 in South Dakota, 24 in Minnesota, and 27 in Montana. Of the 208 smooth bromegrass samples collected, 70% were infected with L. nodorum, 59% with Pyrenophora spp. 52% with Pseudoseptoria bromigena, and 46% with Cochliobolus sativus. Of the 71 isolates of Pyrenophora spp. obtained, 52 were P. tritici-repentis and 19 were P. bromi. The number of P. bromi cultures isolated from the 1981-1983 collections was low because the primary objective was to obtain isolates of P. tritici-repentis. P. tritici-repentis and L. nodorum were widely distributed throughout the northern Great Plains on smooth bromegrass. Thus smooth bromegrass is a good alternative host for L. nodorum and P. tritici-repentis and could provide inoculum for cereal crops planted in the northern Great Plains. Myceium growth rate on sucrose-proline agar and spore production on lima bean agar were useful in separating P. tritici-repentis from P. bromi.