Nanoparticles for the controlled release of fungicides in wood: Soil jar studies using G. Trabeum and T. Versicolor wood decay fungi

Nanoparticles containing a fungicide, tebuconazole or chlorothalonil, were prepared as aqueous dispersions to treat sapwood of southern yellow pine (SYP) and birch using conventional pressure treatment methods. The maximum amount of active ingredient (a.i.) delivered into wood was ca. 2 kg a.i./m3 wood with tebuconazole-containing and 1.6 kg a.i/m3 wood with chlorothalonil-containing nanoparticles. Nanoparticles were prepared using polyvinylpyridine (PVPy) and polyvinylpyridine-co-styrene with 10% styrene (PVPy-10%-Sty) and with 30% styrene (PVPy-30%-Sty) as matrices. Soil jar tests were performed where nanoparticle-treated SYP was exposed to Gloeophyllum trabeum for 16 weeks and nanoparticle-treated birch was exposed to T. versicolor for 12 weeks. Following exposure to G. trabeum, SYP lost ca. 5% of its mass when treated with tebuconazole-containing nanoparticles (PVPy, PVPy-10%-Sty, PVPy-30%-Sty) with atebuconazole content of ca. 0.5 kg a.i./m3 SYP. Similar results were obtained with chlorothalonil-treated SYP (0.5 kg a.i./m3) with PVPy-10%-Sty and PVPy-30%-Sty. Birch exposed to T. versicolor lost ca. 5% mass when tebuconazole (in PVPy and PVPy-30%-Sty) was ca. 0.5 kg a.i./m3, while similar results were found with chlorothalonil (PVPy, PVPy-10%-Sty, PVPy-30%-Sty) only at a biocide content of ca. 1.6 kg/m3 wood