INFECTION BIOLOGY OF BACTERIAL WILT OF FORAGE GRASSES

Infection of perennial ryegrass (Lolium perenne L.), Italian ryegrass (Loliumunultiflorum L.), and timothy (Phleum pratense L.) by Xanthomon as campestris pv. graminis and Xanthomonas campestris pv. graminis and Xanthomonas campestris pv. phlei occurred mainly via wounds rather th an natural openings. Nevertheless, bacteria were detected by isolation and immunofluorescence in plants sprayed with the pathogen, without p rior wounding, and in plants in which intact ears had been dipped in i nocula. High concentrations of bacteria were observed around the stoma ta of perennial ryegrass and timothy by scanning electron microscopy 4 8 h after inoculation. Perennial ryegrass and Italian ryegrass and ind ividual plants of ryegrass and timothy differed in susceptibility to t he pathogens.