Declining Turkey oaks {Quercus cerris) in Central Italy were studied. Bacteria were isolated from woody tissues between necrotic areas and healthy tissues beneath the bark, from apparently healthy tissues and from exudates oozing from the trunk in spring. A total of 98 bacterial isolates were collected. The determination of the bacteria was by fatty acid profiling and biochemical tests. Erwinia berbicola was frequently found both in necrotic and healthy tissues. Ice-nucleation active species were present. None of the species isolated was considered responsible for the decline.

In central Italy, Pseudomonas syringae pv. morsprunorum was isolated from wild cherries {Prunus avium) that had been planted for timber production. Biochemical tests were consistent with those characterizing the pathovar. Pathogenicity tests yielded necrotic lesions, shot holes on the leaves and decoloration of the tissues beneath the twig periderm, but no symptoms on inoculated lilac and pear leaves. In addition, whole-cell protein profiles of the isolates and reference strains were remarkably homogenous when analysed by cluster analysis. All isolates were negative in ice-nucleation activity and in antifungal-compound production. The main symptoms observed in the field were cankers on twigs, branches and trunks, as well as withering of the shoots. Evaluation of the field susceptibility of 18 clones indicated that the following selections must be considered susceptible to the pathogen: Montemignaio, Piantata Catenaia, Puzzolo, Raggiolo, Pozzacce 2, Pozzacce 1, Paradision. AIpe 2 seems to be less susceptible.

Strains of Xanthomonas campestris pv. pruni obtained from Prunus armeniaca. P. domestica, P. persica and P. salicina in different geographical areas were compared for pathogenicity, fatty acid and wholecell protein analysis. Four strains, one per each host plant, were inoculated at the same time, on the foliage of P. armeniaca, P. avium, P. persica and P. salicina cultivars. Mean content of fatty acids of X.c. pv. pruni strains were also compared with those of many strains of X.c. pv. campestris, pv. graminis, pv. hyacinthii, pv. pelargonii and pv. vasculorum. Strains showed a remarkable homogeneity in fatty acids content and whole‐cell protein profiles and principal component and cluster analysis did not reveal any grouping according to original host or geographical origin. However, X.c. pv. pruni strains can be grouped apart from the other X. campestris pathovars. There appears to be no pathogenic specialization among the strains tested, however, they varied in aggressiveness to host plants and host plant in susceptibility. The most of the strains were able to cross‐infect species other that from where they were originally isolated, although, P. avium did not show any symptom of disease. P. persica cv. Sentry and P. salicina cv. Globe Sun, recently licensed as resistant to X.c. pv. pruni. were infected, although to a lesser extent, by some strains.

The capability of carbohydrate utilization shown by some freshly‐isolated phytopathogenic bacteria (i.e. Pseudomonas syringae pv. syringae, Ps.s. pv. actinidiae, Ps.s. pv. lachrymans Ps. cichorii, Xanthomonas campestris pv. campestris) was assessed by means of the API system and compared with that shown by the same isolates when they were subsequently subcultured for I week and for 1 month on nutrient agar and on the medium B of King et al. All isolates showed a differential capability of utilization during the subcultures of the laboratory culture media. In some cases, the utilization of some carbohydrates was not shown during the in vitro growth. On the other hand, the life on bacterial culture media induced the capability to utilize other carbohydrates. The need for standardization of recent techniques for the assessment of organic compound utilization is stressed.

Erwinia carotovora ssp. carotovora can be detected very effectively in lily bulbs by anaerobic incubation of the bulbs followed by homogenization of the scales and plating of the diluted sap onto crystal‐violet pectate medium. This technique, compared with bulb treatments without preliminary anaerobic incubation, also improves the possibility of recovering E.c.carotovora overall at low storage temperatures in the long term. Differences among Lilium cultivars regarding the interaction with E.c.carotovora probably exist; the bacterium multiplied at a higher rate in bulbs of cvs Enchantment, Mont Blanc, Star Gazer and Yellow Blaze. The technique could allow inspection of lily bulbs before planting.