Biomass of the biocontrol agent Idriella bolleyi can be produced in submerged liquid culture as mycelium, conidia, and chlamydospores. Each fraction was separated and quantified. The conidial fraction appeared to be the most thermotolerant, suggesting that this form had the best potential shelf life of the three. Conidia were produced during the early phase of growth and their production did not appear to require any form of nutrient exhaustion or growth rate decay. The highest viability per unit biomass was obtained in carbon-limited medium, with sodium nitrate as the nitrogen source, after 6 h. Maximum biomass was not obtained in this medium until 167 h and, as the biocontrol product is likely to be sold by weight, an acceptable compromise between the two parameters must be found. Excess ammonium chloride in the medium appeared to inhibit growth. A procedure, involving culture homogenization, was adopted in order to estimate potential viability in shake-flask liquid culture.