Scanning electron‐microscopy observations made on the leaves of Italian ryegrass and maize, inoculated withXanthomonas campestrispvsgraminis, oryzaeandoryzicolaclearly showed a difference in the distribution pattern among the different pathovars tested. Pvsoryzaeandoryzicolacould be detected on the leaf trichomes of ryegrass, while pv.graminiswas not. On maize leaves, the attachment of pvsoryzaeandoryzicolato trichomes was much more pronounced than on ryegrass. In addition, pv.oryzaespread further into leaves of maize than did pvsgraminisandoryzicolaand could be detected in masses until at least the sixth day after inoculation. These observations suggest that non‐host plants such as maize could function as alternate inoculum sources of pv.oryzaefor nearby rice pla