Application of fungicides and urea for control of ash dieback

Ash dieback is caused by a highly pathogenic fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea). Possibilities for disease control are limited, and treatment of fallen leaf debris to prevent sporulation of the pathogen is one of the possible options to control the disease. In some cases chemical treatments could be used, but data on effective chemical agents for control of the ash dieback are lacking. The purpose of this study was to examine the effect of different chemical fungicides and urea on the pathogen. Out of eight tested fungicides, mycelial growth in Petri plates as well as development of H. pseudoalbidus apothecia on ash leaf petioles were most efficiently inhibited by carbendazim. Urea also proved to be effective in prevention of apothecial formation. In addition to inhibition of the pathogen, urea accelerates the degradation of treated leaf debris. Therefore, the use of urea for treatment of infected ash leaf debris could be more effective than the use of fungicides and also more environmentally acceptable.