Durability of untreated and thermally modified reed (Phragmites australis) against brown, white and soft rot causing fungi

Abstract

Reed (Phragmites australis (Cav.) Trin. ex Steud.) has been used for thatching roofs since centuries in many regions around the globe. Reed is a renewable resource and provides excellent thermal insulation properties. It is an appealing and very traditional material with known performance when applied as house roofing. However, during recent years an alarmingly high number of prematurely failing roofs were observed in different European countries, but the reason for drastically reduced service lives of thatched roofs is not understood, yet. This study aims therefore on comparative and comprehensive resistance tests to white, brown, and soft rot causing fungi to be performed with reed of different origin. Furthermore, thermal modification of reed was applied as potential environmental friendly technique to improve the durability of reed. Untreated reed of different origin as well as thermally modified reed (TMR) was found to be susceptible to white, brown, and soft rot decay. The latter caused most severe damage to the reed samples, i.e. >40% mass loss, and should therefore be addressed for future studies more in detail. The resistance of reed against the various decay fungi differed slightly between origins and culm sections. Thermal modification significantly improved the durability of reed. Mass loss caused by fungi was reduced by up to 80% at highest treatment intensity. However, the required treatment intensity did not become evident from the results yet. This should be determined in more detailed experiments including further target properties such as water exclusion efficacy, color, brittleness, and further strength properties to assure processing of the material for thatch.