Flowering phenology of selected wind pollinated allergenic deciduous tree species

Systematic phenological observations have been carried out in the Dendrological Garden of August Cieszkowski Agricultural University, Park Solacki, Lasek Golecinski, Przybyszewskiego Street, for two years (2003, 2004). The selected species of deciduous trees, as Betula pendula , Corylus avellana , Platanus x hispanica . There was interdependence between the course of flowering process and weather conditions. Long and frosty winter at the turn of 2002/2003 and subzero mean temperatures in the first quarter of 2003 delayed vegetation. Rapid coming of early spring in the year 2004 accelerate the development of generative organs. Each year spring ground frost during flowering did not inhibit this process. All the investigated tree species are anemophilous and produce large amounts of allergenic pollen grain. They cause allergic reactions throughout the whole period of pollen discharge. Male inflorescences in Corylus avellana, blooming very early, are one of the first plants causing allergic reactions. Betula pendula is the next to bloom, followed by Platanus x hispanica . Observations of phenological phases may provide useful information forecasting the beginning of the period of increased pollen concentration in air.