According to research realized at the University of Exeter, a public research university in the United Kingdom, the ash dieback fungus (Hymenoxyphus fraxineus) could spread quickly and affect more trees than expected. H. fraxineus is a virulent fungal pathogen of ash trees first recognized in Poland, in 1992, and it has spread throughout Europe causing losses. Ash dieback disease is characterized by leaf loss and crown dieback in infected trees. It kills the leaves, the branches, the trunk, and finally leads to the death of the tree. Even though not all trees die of the infection, once infected, trees can’t be cured.
The fungus has two reproductive phases in its life cycle. It was previously believed that the multiplication of H. fraxineus was only possible through sexual reproduction, but Exeter scientists found that asexual spores of the fungus are infectious and can germinate on leaves or infected seedlings via soil. It was believed that the asexual spores functioned as the male in the sexual reproduction, and so they could not germinate alone. This asexual reproduction will allow it to spread more quickly.
Knowing more about the life cycle of this pathogen is important for improving the disease control and for making people conscious that when moving the soil from areas with infected trees, they could be transferring and so spreading the fungus as well.
Original journal article and source of photo: http://www.nature.com/articles/srep34638