Effects of biotic and abiotic factors on the health of horse chestnut trees in an urban area of north-western Poland

The influence of various damaging biotic and abiotic factors throughout many years have reflected in health status of trees in parks and tree lines. The aim of this research was to reveal the present health status of urban trees in Szczecin with special overview on leaf diseases and insect pests. Research was focused on the most planted tree species: Aesculus hippocastanum and A. ×carnea. The most significant damage caused by pathogenic fungi were in trees infected by Oidium spp. (Erysiphe flexuosa (Peck) U. Braun & S. Takam) and Phyllosticta paviae Desm. (Guignardia aesculi (Peck) V.B. Stewart). A greater number of fungal species was found at localities near roads (12 taxa) than at those in parks (9 taxa). The greatest influence by insect pests had C. ohridella on horse chestnut trees where a high damage of leaves of over 80% were observed