The present invention relates to combinations of pyrimethanil, or a salt thereof, and a monoterpene, or a salt thereof, which provide an improved biocidal effect. More particularly, the present invention relates to compositions comprising a combination of pyrimethanil, or a salt thereof, together with a monoterpene selected from thymol and -thujaplicin in respective proportions to provide a synergistic biocidal effect. Compositions comprising these combinations are useful for the protection of any living or non-living material, such as crops, plants, fruits, seeds, objects made of wood, thatch or the like, engineering material, biodegradable material and textiles against deterioration due to the action of microorganisms such as bacteria, fungi, yeasts, algae, viruses, and the like.

A piece of plant material (e.g., wood) can have a lignin content in a range of 5-16 wt %, inclusive, and a microstructure including native lumina bounded by cellulose-based cell walls extending in a first direction. The piece of plant material can be pressed along a second direction crossing the first direction, such that the lumina collapse and facing portions of the collapsed lumina are brought into contact with each other. The piece of plant material prior to the pressing can have a first density. After the pressing, the piece of plant material can have a second density greater than the first density, for example, at least 1 g/cm.sup.3.

A piece of plant material (e.g., wood) can have a lignin content in a range of 5-16 wt %, inclusive, and a microstructure including native lumina bounded by cellulose-based cell walls extending in a first direction. The piece of plant material can be pressed along a second direction crossing the first direction, such that the lumina collapse and facing portions of the collapsed lumina are brought into contact with each other. The piece of plant material prior to the pressing can have a first density. After the pressing, the piece of plant material can have a second density greater than the first density, for example, at least 1 g/cm.sup.3.