Wheat in 3 holds of a bulk dry-cargo vessel was fumigated by applying aluminum phosphide tablets at the rate of 1.77 tablets/m3 of hold capacity. Tablets applied in layers during loading of 2 holds gave better gas distribution and a more efficacious fumigation than stepping the tablets into the surface of the grain in the other hold. Delays in loading of holds fumigated by the layering method sometimes resulted in concentrations of phosphine in the space above the wheat that exceeded the threshold limit value. However, these concentrations were rapidly reduced by ventilation when the main hatch covers were opened. Likewise, in preparation for unloading the wheat at destination, the overhead space of the holds was ventilated rapidly by opening the main hatch covers. Residues of phosphine on wheat samples after fumigation were well below the established tolerance except at one location in each test hold.