15-year peformance of European black pine in provenance tests in north central United States.
Trials of offspring of 24 natural and three planted stands of European Pinus nigra were established at five sites in north central USA. The fastest growing seedlots were from various parts of the eastern range of P. nigra in Europe. Eastern trees were also winter hardy, except in northern Michigan. Trees from Corsica suffered severe winter injury, whereas winter injury in trees from France, Italy and Spain was less severe. Resistance to Dothistroma pini and Cenangium ferruginosum was greatest in trees from Yugoslavia, Austria and northern Greece. Genetic differences between populations in resistance to Dioryctria zimmermani, Neodiprion sertifer and Rhyaciomia buoliana were observed. The combined data from this trial and others in West Germany and New Zealand indicate that P. nigra can be subdivided into six taxonomic varieties.