At certain times of the year, depending on the inherent nature of the fungus and various environmental factors, the sclerotia germinate and form either mycelium which can infect a host, or an apothecium. Infection of host plants by mycelium can occur at or beneath the soil-line. Sclerotia germinate in the presence of exogenous nutrients and produce hyphae which invade nonliving organic matter, forming mycelium which then infects living host tissues. Penetration of the host cuticle is achieved by mechanical pressure. Mycelium infection is unlikely to infect plants located more than 2 cm from a sclerotium.
Carpogenic germination produces an apothecium which releases ascospores that disseminate by air.
Generally, 10-20 C is the optimum temperature range for carpogenic germination. Under favorable conditions, including adequate moisture, ascospores germinate within 3-6 hours of release. In one study, apothecia collected from the field discharged ascospores continuously for seven days in the laboratory. Ascospores infect nonliving host tissues, germinate, and inundate the nonliving plant part with mycelium. Then, the fungus invades healthy plant tissues with mycelium.