RELATIONSHIP OF PSEUDOMONAS-SYRINGAE PV TABACI RACES TO THE RHIZOSPHERE OF WISCONSIN-GROWN TOBACCO

Isolates of Pseudomonas syringae pv. tabaci, including 21 strains of t he wildfire pathogen and 2 strains of the angular leafspot pathogen, w ere isolated from 143 rhizosphere and soil samples collected from 11 t obacco fields in Wisconsin. These pathogens were isolated by inoculati ng rhizosphere and soil washings into tobacco leaves and isolating the bacteria from wildfire or angular leafspot lesions that developed on the leaves. The wildfire isolates were from the rhizospheres of tobacc o and Panicum capillare and from soil. While the majority of these wer e from wildfire-diseased fields, one isolate was from a field without disease symptoms; both angular leafspot isolates were from fields with out angular leafspot symptoms. The majority of wildfire isolates were race 1, but three were race 0, and one was a new race; In three fields multiple races of wildfire were found. Both angular leafspot isolates were race 1. Two wildfire and one angular leafspot isolates were from fields where the cultivars were resistant to the races isolated.