Mesophilic heterotrophic, aerobic or facultatively anaerobic bacteria that grow on yeast tryptone glucose extract agar were isolated from the surface of olive leaves of 3 or 4 different ages in January, April, July, and October from 1984 to 1989. Unweighted average linkage cluster analysis on either the Jaccard coefficient or the simple matching coefficient recovered 1,701 representative strains in 32 phena defined at the 70% and 80% similarity level, respectively. Of these, 25 were identified to genus or lower level. From the identity of the representative strains, the frequency of occurrence among the phylloplane bacteria over the 6-year period was estimated at 51% forPseudomonas syringae, followed byXanthomonas campestris (6.7%),Erwinia herbicola (6%),Acetobacter aceti (4.7%),Gluconobacter oxydans (4.3%),Pseudomonas fluorescens (3.9%),Bacillus megaterium (3.8%),Leuconostoc mesenteroides subsp.dextranicum (3.1%),Lactobacillus plantarum (2.8%),Curtobacterium plantarum (2.2%),Micrococcus luteus (2.2%),Arthrobacter globiformis (1.4%),Klebsiella planticola (1.2%),Streptococcus faecium (1.2%),Clavibacter sp. (0.98%),Micrococcus sp. (0.82%),Serratia marcescens (0.81%),Bacillus subtilis (0.57%),Cellulomonas flavigena (0.4%),Erwinia sp. (0.37%),Zymomonas mobilis (0.3%),Bacillus sp. (0.29%),Alcaligenes faecalis (0.27%),Erwinia carotovora (0.08%), andPseudomonas aeruginosa (0.04%). Bacterial communities on leaves of a given age at a given time during any one year displayed a very similar structure but differed significantly from those on the leaves of the same age at a different time or on the leaves of a different age at any time during any one year. Communities on the leaves of a given age at a given time of the year were invariably dominated by one or another of only 9 taxa, which accounted for 22 to 98.5% of the isolates from those leaves. The communities on 10- and 13-month-old leaves were invariably made up of fewer taxa than those on younger leaves at the same time of the year.

There were characteristic seasonal fluctuations in the populations of most of the bacteria. The abundance of P. savastanoi on healthy leaves in April and October supports earlier suggestions that the phylloplane of the host may be an important source of readily available inoculum in the epidemiology of olive knot disease.

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Data assimilation has the potential to improve flood forecasting. However, research efforts are still needed for an effective development of assimilation schemes suitable for operational usage, especially in case of distributed hydrologic models. This work presents a new assimilation system of streamflow data from multiple locations in a distributed hydrologic model. The system adopts a mixed variational‐Monte Carlo approach, and is here tested with the hydrologic model MOBIDIC, that is part of the operational flood forecasting chain for Arno river in central Italy. The main objective of the work is to evaluate the actual gain that the system can lead to flood predictions in a real‐time operational usage. Accordingly, a specifically designed assessment strategy is employed. It is based on several hindcast experiments that include both high flow and false alarm events in the period 2009–2014 in Arno river basin. Results show that the assimilation system can significantly increase the accuracy of flow predictions in respect to open loop simulations in both cases. Specific performances depend on location and event, but in the majority of cases the error on predicted peak flow is reduced of more than 50% with a lead time of around 10 h. The analysis reveals also that the structure of the hydrologic model, the coherence between observations at various sites, and the initial watershed saturation level, considerably affect the obtainable performances. Conditions that may lead to a worsening of open loop predictions are identified and discussed.