Fumigation of wood with aluminium phosphide for protection against fungi

The search for alternatives to the environmentally harmful fumigant methyl bromide has led to the evaluation of phosphine as preshipment and in-transit treatments for logs and sawn timber. The biological activity of aluminium phosphide against wood decaying fungi was determined using agar plate and soil block methods. Malt agar bioassay was carried out using five concentrations of aluminium phosphide against wood decaying white (Trametes versicolor) and brown rot (Oligoporus placentus) fungi. Minimum fungicidal concentration of fumigant was 1.0% for T. versicolor and 1.3% for O. placentus. Soil block bioassay was carried out on softwood (Pinus roxburghii) and hardwood (Populus deltoides). Wooden blocks of specific sizes were fumigated with five different concentrations of aluminium phosphide and subjected to the test fungi. Results revealed that 4.9% concentration at 91.76 g m-3 retention of aluminium phosphide gave more than 90% protection to the wood against white and brown rots. Treated specimens did not exhibit any change in dimensions after exposure to fungi but control specimens were badly affected.