Water and temperature relations and microconidial germination of Fusarium moniliforme and Fusarium proliferatum from maize.

The effects of water activity (aw, 0.994–0.85 = 0.4–21.0 (−)MPa water potential), temperature (5–42 °C), and their interactions on microconidial germination of three isolates each of Fusarium moniliforme and Fusarium proliferatum were determined in vitro on a maize meal extract medium. Temporal germination rates of microconidia of isolates of both species were significantly influenced by both aw and temperature. Germination was very rapid at >0.94 aw with an almost linear increase with time. Germination rates of microconidia of F. moniliforme were slower than those of F. proliferatum isolates at marginal aw levels and 5–25 °C, while at higher temperature (30–37 °C), the former germinated more rapidly than the latter. The aw minima for germination of isolates of both species was 0.88, with none occurring at 0.85 aw over a 40-day incubation period. At 37 °C, isolates of F. moniliforme had slightly lower aw minima than those of F. proliferatum. The narrowest range of aw for germination was at 5 °C, and none ...