Accidental mold/termite testing of high density fiberboard (HDF) treated with borates and N’N-naphthaloylhydroxylamine (NHA)

IRG/WP 03-10462

S N Kartal, H H Burdsall Jr, F Green III

High density fibreboard (HDF) was made from beech and pine furnish (50:50) and treated with boric acid (0.1-3%), borax (0.1-3%) or N'-N-(1,8-naphthalyl) hydroxylamine (NHA) (0.1-1%) prior to gluing with urea formaldehyde (UF) resin in order to determine resistance to Eastern subterranean termites (Reticulitermes flavipes Kollar), the most economically important termite species in North America. HDF and southern yellow pine (SYP) sapwood specimens were tested in a modified no-choice soil-block test normally used for fungal decay tests for 5 weeks. Within the first week of incubation, all HDF specimens were heavily overgrown with a variety of mold fungi. This same contamination was not seen in regular SYP specimens tested under the same conditions. Mold contamination did not appear to inhibit termite attack in any measurable way. Weight loss in control HDF specimens was 28% after 5 weeks while weight loss in control SYP was 12% under similar test conditions. Selected treatments with boric acid, borax, didecyl dimethyl ammonium chloride (DDAC) and NHA reduced termite attack in HDF and SYP specimens below 5% weight loss. Synergy was not observed for boron containing compounds and NHA. We conclude that i) soil contact accelerates HDF mold contamination and termite damage in the absence of termidicides ii) HDF made with UF is more susceptible to moisture acquisition and mold contamination than SYP iii) NHA does not act as a mildewcide iv) 3% borates retard both mold and termite damage; and v) HDF is less durable, and requires more preservative to protect, than SYP.

Keywords: HDF, termite damage, preservative treatment, borate, DOT, termite-fungus interaction

Conference: 03-05-18/23 Brisbane, Australia

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