Fusarium head blight pathogens isolated from fusarium-damaged kernels of wheat in western Canada, 1993 to 1998

Survey results from 1993 to 1998 for fungi isolated from fusarium-damaged kernels of wheat are presented. There is compelling evidence that Fusarium gramineanrm has recently been spreading westward from southeastern Manitoba, replacing less pathogenic Fusarium species as the principal fusarium head blight (FHB) pathogen. This movement has been accompanied by increasing economic losses from the effects of FHB. Environmental factors such as a lower average daily temperature in June and July may be influential in limiting the damage from F. graminearum in the western prairies, where F. graminearum currently is rare. However, precipitation levels at anthesis equal to those in the areas presently affected by economic levels of FHB occur in many western crop districts, suggesting that precipitation levels during the period of anthesis will likely promote further westward spread of this pathogen. The potential role of infected seed as a mechanism for long-distance dispersal of F. graminearum is considered.