Cultural control of Cameraria ohridella on horsechestnut in urban areas by removing fallen leaves in autumn

Since the 1990s, the leafminer Cameraria ohridella has spread in central and southern Europe causing heavy damage on horsechestnut (Aesculus hippocastanum). Because biological control of the pest is not yet a reality, other measures must be adopted. Cultural control by removing fallen leaves of horsechestnut in autumn has often been proposed, and with this 3-year study the effectiveness of this practice under urban conditions has been shown and measured. The almost complete removal of leaves caused a significant reduction in infestation. The area of leaf surface injured decreased on average by more than 90% in early June, three quarters in late July, and a third in late August, and early leaf fall was always avoided. The proximity to sites with no leaf removal reduced the benefits of leaf removal as the season advanced. In the context of Integrated Pest Management, this cultural method contributes significantly to reduce C. ohridella damage.