Cold Hardiness and Foliar Disease Resistance of Northern American and Asian Fragaria

Abstract

Thirty-two wild strawberry genotypes and two commercial cultivars were obtained from the US Department of Agriculture (USDA), Agricultural Research Service (ARS), National Clonal Germplasm Repository-Corvallis (NCGR) and planted in the field to test cold hardiness and foliar disease resistance at the University of Minnesota North Central Research and Outreach Center at Grand Rapids, MN. This station is located in USDA plant hardiness zone 3b. Among the 34 genotypes tested, Fragaria iinumaewas sensitive to powdery mildew, leaf scorch, frost and mid-winter injury while F. nipponicawas resistant to powdery mildew and leaf scorch. Fragaria iinumaesuffered severe injury after winter 2009-10, while F. nipponicaand F. orientalissurvived that winter well, producing dense and vigorous plants in 2010. These species could be potentially useful diploid or tetraploid parents in breeding programs developing strawberries for the mid-western United States. Fragaria chiloensisPI 637983, was similar to the standard cultivars for winter hardiness and disease resistance. Wild strawberries bloomed earlier and had softer, smaller fruit than did the commercial F.× ananassa‘Jewel’ and ‘Mesabi’. Fragaria nipponicahad the softest fruit. Fragaria orientalisPI 637933 and PI 637939 were notable for their pleasing taste and aroma, while most Fragaria nipponica, F. iturupensis,and F. virginianawere very sour. The feral F.× ananassaPI 641087 and PI 641088 may have the greatest immediate utility, with a combination of winter hardiness and excellent disease resistance, for octoploid breeding programs.