Compartmentalization of American Elm Tissues Infected by Ceratocystis ulmi. A. Shigo, Chief Scientist, U.S. Department of Agriculture, Northeastern Forest Experiment Station, Durham, NH 03824. J. T. Tippett, Research Plant Pathologist, U.S. Department of Agriculture, Northeastern Forest Experiment Station, Durham, NH 03824. Plant Dis. 65:715-718. Accepted for publication 15 January 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/PD-65-715.

American elm trees compartmentalized tissues infected by Ceratocystis ulmi where the cambium was not killed. After infection, the cambium that was not killed formed a barrier zone that separated infected xylem from newly developing healthy xylem. The barrier zones in the sections studied were tangential sheets of axial parenchyma bridging swollen ray parenchyma cells. Recovery of an elm tree after infection may depend on its ability to compartmentalize infected wood to small volumes rapidly and to generate new healthy tissues.