In recent years, North-western Spain has experienced an increase in the cultivated area of olive trees. The main propitious areas for olive groves are the Miño and Sil basins, as a consequence of their Oceanic climate with Mediterranean influence. The objective of this study is to determine the characteristics of reproductive biology, phenological and aerobiological behaviour of olive trees in the most northerly new plantation areas of the Iberian Peninsula. The study was carried out in an olive grove growing Olea europaea L. cv. ‘Arbequina’ located in Quiroga (Lugo) from 2016 to 2018. The phenological observations were based upon the main growth stages following the Biologische Bundesanstalt Bundessortenamt and Chemical industry (BBCH) scale. To predict the onset of flowering, a thermal time model was used in order to quantify the chill requirements, and growing degree-days were applied to determine the heat requirement. The production, viability and germination rates of Olea pollen were evaluated from samples selected in nine individual trees for the phenological survey. The aerobiological study was conducted by means of a Hirst-type pollen trap located in the centre of the olive grove. The vegetative period of the olive tree in the study area lasted an average of 259 days. The important phenological stage 6 (flowering) was the shortest stage. An average of 704 Chilling Hours (CH) with a threshold of 2.5 °C was required to overcome the chilling period, 1139 Growing Degree Days (GDD) for the beginning of flowering, and 4463 GDD for harvest. The pollen production per anther was 82589 grains (± 14084 pollen grains), with a rate of 81% viability and 12% pollen tube germination. The main pollen season started on average on May 20th and ended on June 16th with an average duration of 27 days and an annual pollen integral of 833 pollen grains. The low pollen concentrations could be a consequence of the Northern location of the forest, in a bioclimatic transition zone between the Eurosiberian and the Mediterranean areas, at the limit of olive tree distribution.

Allergies became a major public health problem, identified as an important global pandemic with a considerable impact on the worldwide economy. In addition, a higher prevalence of pollen Type I sensitization cases in urban environments in comparison with the rural territories was detected. Our survey sought to assess the main biological pollution episodes caused by the aeroallergens of the major allergenic tree species in urban environments. A Hirst-type volumetric device was used for pollen sampling and a Burkard Cyclone sampler for the detection of tree atmospheric allergens over two years. The main allergens of Alnus, Fraxinus, Betula, Platanus and Olea, were detected in the atmosphere. Three peaks of important pollen concentrations were recorded throughout the year. The developed regression equations between pollen counts and allergen proteins registered great R² values. The number of days with probability of allergenic symptoms was higher when the pollen and allergen data were assessed altogether. Fraxinus allergens in the atmosphere were detected using Ole e 1 antibodies and the Aln g 1 allergens with Bet v 1 antibodies, demonstrating the cross-reaction processes between the principal allergenic proteins of the Oleaceae and Betulaceae families. Long Distance Transport processes (LDT) showed that pollen from Betula populations located in mountainous areas increased the secondary peaks of pollen and allergen concentrations, and air masses from extensive olive orchards of North-Eastern Portugal triggered the highest concentrations in the atmosphere of Olea pollen and Ole e 1 allergens.

The most common fungal diseases of Olea europaea are olive leaf spot (Fusicladium oleagineum), anthracnose (Colletotrichum spp.) and cercospora leaf spot (Pseudocercospora cladosporioides). To know the fungal load during the vegetative olive cycle, an aerobiological and phenological study was conducted in an olive grove in North-West Spain. For the aerobiological study, the Spanish Aerobiological Network protocol was followed using a Hirst-type spore trap. The goal of the study was to assess the spore concentrations in the atmosphere of the olive grove and their relationship with the meteorological parameters by applying statistical procedures, including a Cluster analysis, Spearman’s correlation test and PCA analysis. The most abundant spores belong to Fusicladium, registering the double of values than Colletotrichum and Pseudocercospora. The hours with the highest spores’ presence were from 11:00 to 12:00 for Fusicladium and Colletotrichum, and from 17:00 to 18:00 for Pseudocercospora. The Spearman’s and PCA test showed a positive association between temperature and relative humidity with the spores’ concentrations. The combination of meteorological, phenological and aerobiological parameters is a useful tool to understand the ecological behavior of the considered phytopathogenic fungal spores in order to develop futures strategies for the integrated management of fungal olive diseases in areas at the limit of this tree distribution.