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Successions of Microorganisms and Patterns of Discoloration and Decay after Wounding in Red Oak and White Oak. Alex L. Shigo, Principal Mycologist, Northeastern Forest Experiment Station, USDA Forest Service, Durham, New Hampshire 03824; Phytopathology 62:256-259. Accepted for publication 8 September 1971. DOI: 10.1094/Phyto-62-256.

Trunks and roots of 18 mature red oaks, Quercus rubra, and 5 white oaks, Q. alba, were dissected to determine the patterns of discolored and decayed wood associated with 22-year-old basal fire wounds and mechanical wounds inflicted during subsequent salvage operations. The columns of discolored and decayed wood had advanced farthest along the sapwood-heartwood boundary present at the time of wounding. The discolored and decayed tissues associated with the wounds were confined to the tissues present when the wounds occurred. The heartwood cylinder constricted abruptly below the root collar. Heartwood formation was retarded around wounds. Complex patterns of discolored and decayed wood occurred in the root-trunk transition zone. Isolations for microorganisms were made in a systematic way from columns of discolored and decayed wood in 19 trees. Bacteria and nonhymenomycetous fungi were isolated consistently from columns that contained only discolored wood, and from the discolored wood at the distal margins of columns that contained decay. Hymenomycetous fungi were isolated commonly from the tissues at the border of discolored and decayed wood. A large variety of microorganisms was isolated from the advanced decay. The results indicate that discoloration and decay are compartmentalized within the tissues present at the time of wounding, and that successions of microorganisms follow wounding in oaks.

Additional keywords: fire wounds on oaks.