Winter hardiness in the U.S. Department of agriculture malus core collection

A group of 200 Malus accessions have been designated as a "core" of the complete collection held by the Plant Genetic Resources Unit (PGRU) of the U.S. Department of Agriculture (USDA) at Geneva, New York. A replicated planting of this core collection was established at Excelsior, Minnesota, USA in 1994. In 2002, the planting was evaluated for winter injury (WI) accumulated over 8 winters. The minimum temperatures during this period were lower than -26°C on several occasions with the lowest temperature of -38°C occurring in February 1996. Among the hardiest entries were accessions M. asiatica, M. baccata, M. brevipes, M. floribunda, M. ioensis, M. orientalis, and M. sieversii. Among the hardiest M. × domestica entries were cultivars from Canada, Russia and the northern US including the cultivars Antonovka Kamenichka, Cortland, Haralson, Keepsake, McIntosh, Novole, Petrel, Viking, Yellow Transparent.