OCCURRENCE OF SPECIFIC REACTIONS INDUCED BY PSEUDOMONAS-SYRINGAE PV SYRINGAE ON BEAN PODS, LILAC AND PEAR PLANTS

A study on the pathogenicity of 81 strains of Pseudomonas syringae pv. syringae (PSS) isolated from 16 different hosts was conducted on lila c plants, bean pods and pear seedlings, using artificial inoculation. Only 55 among the 81 strains induced a necrotic lesion when inoculated on lilac leaves. On bean pods, all but one of the bean isolates, and only eight strains among the 52 strains isolated from other hosts, ind uced typical green water-soaked lesions. On pear leaves, only pear iso lates incited a typical progressive necrotic reaction, the isolates fr om other origins inducing no symptoms or a weak reaction limited to th e inoculation point. This study indicates that in addition to the larg e variability observed in aggressiveness of PSS strains, host specific ity occurred on bean and pear.