Since some years, new treatment technology to protect wood against wood destroying fungi is introduced. Limited knowledge on their resistance to water organisms is available. Therefore, the resistance of chemically modified wood was assessed in a field test according to the European Standard EN 275 over a period of 3 resp. 5 years at sites in the North Sea and the Baltic Sea. Scots pine (Pinus sylvestris) sapwood was treated with DMDHEU (dimethylol-dihydroxy-ethylen-urea), MMF (methylated-methylol-melamine), TEOS (tetra-ethoxy-silane) and PF (Phenol-formaldehyde). In addition, acetylated and untreated Radiata pine (Pinus radiata) was tested. The content of the modification agent in the exposed samples was determined annually in order to determine the stability of the treatment during the exposure in seawater against leaching during the first three years of exposure. The chemical contents stayed stable, indicating that leaching of modification chemicals did not occur. The common shipworm (Teredo navalis) was the only wood boring organism found at the two test sites. Most controls were destroyed within one year. Modified specimens showed varying severeness of attack by T. navalis, depending on the modification method. The resistance of resin treated wood seems to depend not only on the type and concentration of resin, but also on process parameters.

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