EFFECTS OF PHOSPHINE FUMIGATION ON SURVIVAL AND GROWTH OF STORAGE FUNGI IN WHEAT

Wheat of 0.80 water activity (a(w) (16.2% m.c.) and 0.86 a(w) (18.3% m.c.) was inoculated with Eurotium chevalieri, Aspergillus flavus or A. parasiticus and exposed to 0.1 g phosphine m-3 for 2 weeks at 28-degrees-C. Control samples were exposed to air under the same conditions. The fungal flora was determined before and after all treatments. Storage of the moist grain in phosphine rather than air led to a less rapid development of most storage fungi, but did not prevent growth completely. The level of inhibition observed suggests that phosphine may be useful in retarding fungal spoilage during short-term storage of high moisture grain (15-19% m.c. for wheat). Phosphine at 0.1 gm-3 caused only a slight decrease in populations of fungi that were unable to grow at the a(w) of the stored grain, indicating that phosphine has only a small effect on non-growing mycelium and dormant conidia.