SUSCEPTIBILITY OF EUROPEAN OAKS GROWN IN SOUTH CAROLINA AND WEST VIRGINIA, USA TO CERATOCYSTIS FAGACEARUM
WL MACDONALD1, FH TAINTER2, J PINON3 and ML DOUBLE1
1Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV 26506-6057, USA; 2Department of Forest Resources, Clemson University, Clemson, SC 29634, USA; 3INRA, 54280 Champenoux, France
Background and objectives
Materials and methods
In South Carolina, provenances of the following European white oak species were evaluated: Quercus pedunculata, Q. petrae, Q. pubescens and Q. sessiliflora. North American white oak species included as resistant controls were Q. alba and Q. stellata. Susceptible red oak controls were Q. rubra and Q. falcata. In West Virginia, European white oak provenances evaluated were Q. pedunculata and Q. sessiliflora. Resistant North American white oak controls included Q. alba and Q. prinus. Q. rubra served as the susceptible red oak control.
At each location, symptom ratings began approximately 1 month after inoculation and continued through the 1996 and 1997 growing seasons. Symptom expression was evaluated by rating the portion of the crown of each tree that exhibited wilt and dieback symptoms. A report on the preliminary research associated with this study has been published .
Results and conclusions
In West Virginia, there was no significant difference in symptom expression between the European and North American red oak species with regard to species, provenance or inoculation site at the final 1996 evaluation. Symptoms for the European white and North American red oak species averaged 96 and 100%, respectively, while American white oak species averaged 20%. After the 1997 growing season, symptoms in European and North American red oak species approached 100% while the North American white oaks averaged 22%. Unlike South Carolina, the only surviving trees were those representing the two North American white oak species. The significant mortality that occurred among the European white oaks indicates that unlike their resistant North American white oak relatives, they could be seriously impacted by the accidental introduction of C. fagacearum into Europe.