UTILIZATION OF PHOSPHINE FUMIGANT FOR THE CONTROL OF FUNGI NATURALLY PRESENT IN STORED PADDY RICE (ORYZA-SATIVA, L)

Freshly harvested paddy rice, with initial water activities (a(w) of 0 .84 and 0.90 (16.0% and 19.1% moisture content on a wet basis, respect ively), was exposed to 0.0; 0.5; 1.0 and 1.5mg phosphine (PH3)/L at 28 degrees C for 7 and 14 days, Fumigant concentrations were determined after each exposure period. Fungal flora was evaluated before and afte r all treatments by direct plating onto two media. The results showed a decrease of total infected grains as the fumigant concentration incr eased. After all. treatments, a better control was observed for field fungi at 92% relative humidity and for storage fungi at 85% relative h umidity. The 0.5mg PH3/ L concentration was probably sufficient for ri te control of Eurotium spp development at both relative humidities, Th e results suggest that the 1.0 and 1.5mg PH3/L. concentrations were ef fective for controlling storage fungi after the two exposure periods a t both relative humidities. The lowest percentage of fungal infection of grains was obtained with 1.5 mg phosphine/L at the highest relative humidity, The protection period offered by the fumigant depended on t he concentration applied.