Rapid assessment of antimould efficacies of pressure-treated southern pine

A membrane-screening method was developed in conjunction with flow cytometric (FC) analysis for determining the efficacies of antimould pressure-treatment formulations for mould species of cosmetic significance on southern pine. Fusarium subglutinans, Aspergillus flavus, Penicillium chrysogenum, and Paecilomyces spp. were the predominant moulds colonizing surfaces of the variously treated pine stored in sealed plastic bags over 3- to 6-month periods. Nylon membranes placed directly on pressure-treated pine and membranes saturated with the various formulations were inoculated with the conidia of selected moulds. FC analysis of conidia stained with propidium iodide (PI) before and after exposure to the pressure-treatment formulations permitted a rapid assessment of the inocula and selection of those pressure-treatment formulations with probable inhibitory activity versus probable nonactive preparations. Recoveries of the fungi from the membranes over 9-14 days were in general agreement with the emergence of colonizing fungi on the similarly preserved uninoculated pine stored in sealed plastic bags for 6 months. This combination of procedures provided for a relatively rapid assessment of preservative formulations designed to provide enhanced efficacy against surface mould growth on lumber during storage and retail display.