A Note on the Effect of Microorganisms on Creosote Penetration in Pinus Elliottii Sapwood and Eucalyptus Diversicolor Heartwood

Green logs of Pinus elliottii and Eucalyptus diversicolor were dried in hot creosote. It was observed that certain specimens, in addition to the normal treated outer sapwood, showed abnormal penetrability in discrete pockets of cells. In the case of P. elliottii, there had been a heavy infection by bacteria, probably via a branch trace, some 3 feet away from the abnormally treated zone. The microorganisms had built up in large numbers in the rays, where they had depleted cell contents. They had also attacked bordered pits and tertiary lamellae in tracheids. All three features would produce increased absorption of creosote. The difference in nutrients available between heartwood and across the sapwood ray cells is believed to have influenced the production of bacterial slimes in the more inner sapwood. Their absence in the heartwood produced better penetration than in this zone of sapwood, where such substances could have blocked the flow of preservative. Attack of rays, bordered pits, and tertiary lamellae in the heartwood contributed to the abnormal absorptivity. In E. diversicolor a dematiaceous fungus was isolated from the discolored zone of heartwood in an untreated log which corresponded to the unusually permeable zone in the treated specimens. Microscopically, the fungus had broken down ray cells in the heartwood, and had freely penetrated interfiber Pits and perforated vessel tyloses. An organic substance was found to be closely associated with the fungal hyphae and was responsible for the discolored appearance of the infected zones. It is possible that this substance reacted with the hot creosote to form a more mobile solution. Fungal disintegration of thin walled ray parenchyma cells, attack of pits, and colonization of vessels resulted in the abnormal penetration of creosote in the heartwood.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member