Seasonal availability of inoculum of Stagonospora nodorum in the field in the southeastern US

The presence of inoculum of Stagonospora nodorum was detected by placing wh eat seedlings in the field for short periods throughout the year. Inoculum was monitored in growing wheat crops, on wheat stubble, and in adjacent fie lds of tall fescue over a three year period. S. nodorum was found throughou t the year but was detected least often during the summer months and in Oct ober, the driest month of the year. Seedlings became infected when placed i n wheat stubble up to 22 months after wheat was harvested. S. nodorum was i nfrequently found in the tall fescue within 17 m from the edge of the wheat fields. The wheat biotype of S. nodorum was recovered from wheat and barle y seedlings, but the barley biotype was not found. The results show that in oculum of S. nodorum is produced within a field and is disseminated only sh ort distances. The results provide additional circumstantial evidence that the asexual stage is the source of inoculum in the southeastern U.S.