Air-borne ascospores are the most important means of spread. Mycelium from sclerotia can also cause infection, but usually this mode of infection stays within an area. Moving contaminated soil (on farm equipment, shoes, infected seedlings) and fertilizing with manure from animals fed infected plant debris, are two common ways of spreading sclerotia or mycelium from place to place. Irrigation also has been shown to be involved in the spread of Sclerotia spp. from field to field. Irrigation transported sclerotia remained viable for at least 10-21 days in flowing water. In addition, seed may be an infective source, either from contaminating sclerotia or internal mycelium. However, support for this method of transmission is questionable.