The fungus mycelium (that is the mass of thread like parts that grows inside the daylily leaves) makes spores. It can produce either type of spore and changes from producing one type to the other. In the summer the fungus inside the infected daylily produces summer rust spores. As winter approaches it starts to produce the over-wintering spores. If the fungus survives the winter inside an evergreen daylily leaf than it can switch back to producing summer spores. The summer spores it produces do not change into winter spores that is the spores that have been produced are not changed but what spores are being produced by the fungus does change . The fungal mycelium inside the daylily can change back to producing summer spores if it survives.
