HPLC pattern and composition of leaf polyphenols in pear trees infested by Psylla Pyricola and mechanically damaged

In 1994 we reported the first results of an experiment aimed to study the pattern and structure of induced phenolic compounds in pear trees infested by Psylla pyricola, a pear leaf sucker or mechanically damaged. Here, we present the results of further chromatographic and mass spectral analysis performed on extracts of leaf samples collected at various-time intervals (before infestation and damage, first nymphs on leaves and after 12 hours, 24 hours, 2 days, 5 days, 14 days and 30 days, respectively) from pear trees which were either Psylla-infested, or mechanically damaged, or both. The results are compared to samples from an uninfested control tree of the same age and size.