EFFECT OF PLANING ON MOLD SUSCEPTIBILITY OF KILN-DRIED AND AIR-DRIED SCOTS PINE (PINUS-SYLVESTRIS L) LUMBER

Redistribution of water-soluble sugars and nitrogenous compounds by dr ying increases the nutrient content of the lumber surface. Kiln and ai r drying cause different redistribution of the soluble sugars and nitr ogen, leading to different susceptibility of the lumber surfaces to mo uld growth. The present work examines the effects of planing and diffe rent drying treatments on mould susceptibility. Planks of Scots pine ( Pinus sylvestris L.) were dried using a fast and a slow kiln drying sc hedule, and also air drying. After drying, the mould fungus Penicilliu m brevi-compactum was inoculated on samples with an original or a plan ed surface. The mould growth was classified by visual examination. The original surfaces of fast kiln-dried lumber are more susceptible to m ould growth than those of slow kiln-dried lumber. Planing of the lumbe r removes the nutrient-enriched zone at the lumber surface after both fast and slow kiln drying and decreases the susceptibility to mould gr owth. The resistance of air-dried material to mould, however, is not i mproved by planing, since the zone richest in nutrients is located dee per below the original surface than in kiln-dried material.