Bacterial Mosaic, a New Corynebacterial Disease of Wheat

Bacterial mosaic is a foliar disease of wheat; characteristic symptoms are small yellow lesions, more or less uniformly distributed over the leaf. It was discovered in Nebraska in the spring of 1976. By 1979, the pathogen was distributed over an 800-km range and had been isolated from 16 cultivars of winter wheat. The pathogen is Corynebacterium michiganense subsp. tessellarius, a Gram-positive coryneform. Wheat was the only host that showed symptoms after inoculation. The pathogen reached high population levels (> 106 colony-forming units per gram of fresh weight) without apparent symptoms in tomato and in six of nine gramineous plants in greenhouse tests.