Bird's eye lesions of tomato fruit produced by aerosol and direct application of Clavibacter michiganensis subsp michiganensis

Development of the bird's eye fruit lesion of tomato was studied by inocula ting flowers and the surface of young tomato fruit with strains of Clavibac ter michiganensis subsp. michiganensis. Flowers were sprayed once or twice with C. michiganensis subsp. michigonensis at 10(8) CFU/ml. The maximum inc idence (80%) and severity (12 spots/fruit) of spotted fruit resulted when i noculum was sprayed twice, 3 days apart. Flowers were most susceptible to i nfection 2 days after anthesis. When a paintbrush was used to apply inoculu m to the surface of small fruit, a large number of fruit spots (less than o r equal to 456 spots/fruit) resulted. Even strains determined to be avirule nt based on a tomato stem inoculation assay and a hypersensitive response o n four-o'clock leaves (Mirabilis jalapa) were able to produce fruit spots, although at a reduced level. The inoculation methods developed in this stud y can provide opportunities to observe subtle host-pathogen interactions be tween C. michiganensis subsp. michiganensis strains and tomato and to help formulate methods to quantify infection.