The two P. syringae strains examined were known to differ in fitness on bean plants under field conditions. The strains appeared to be similar in ability to be dispersed. However, they differed in relative amounts of spread presumably due to their differential growth abilities on bean leaves. Any technological use of bacteria in an open system presents the potential risk that bacteria may move from the site where they are used to one where they may pose some risk of an adverse effect. In a typical agricultural or minimally managed ecosystem, a patchy array of different crops or other plants may be interspersed with areas where no plants exist.
Successful spread requires both dispersal to a new habitat and growth on that habitat.
The literature suggests that rainsplash dispersal and aerosol dispersal are probably the most important means of spread of bacteria in the phyllosphere. If rainsplash and aerosol dispersal are the important modes of dispersal, then the likelihood of dispersal should diminish rapidly with distance. Ballistic particles generated by rainsplash travel only relatively short distances, and dilution of bacteria released from the phyllosphere in aerosols occurs very rapidly, and hence the likelihood of redeposition of aerosols decreases rapidly with distance from a source plant. Given these assumptions, spread over a canopy of a plants on which rapid growth is likely should be facilitated. The bacteria may disperse any distance, grow on the leaves upon which they land, and redisperse to land on leaves somewhat farther from the original source.