Sclerotia undergo either hyphal or eruptive germination. Hyphal germination is characterized by the growth of individual strands of hyphae from the sclerotial surface while eruptive germination is characterized by plugs or aggregates of mycelium bursting through the sclerotial surface. The quantity of mycelial growth and the energy needed for infection is dictated by the type of sclerotial germination that takes place. A food base of nonliving organic matter must be present for hyphally germinating sclerotia to infect host tissue because mycelial growth is sparse. However, mycelium from eruptively germinating sclerotia can infect host tissue without requiring an exogenous food base.
Growth is possible within a broad pH range, though best on acidic soils.
The optimum pH range for mycelial growth is 3.0 to 5.0, and sclerotial germination occurs between 2.0 and 5.0. Germination is inhibited at a pH above 7.0. Maxiumum mycelial growth occurs between 25 and 35 C with little or none at 10 or 40 C. Sclerotial formation is also greatest at or near the optimum temperature for mycelial growth. Mycelium is killed at 0 C, but sclerotia can survive at temperatures as low as -10 C. High moisture is required for optimal growth of the fungus. Sclerotia fail to germinate when the relative humidity is much below saturation.