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The 2009 ASHS Annual Conference

Evaluating a Columnar Population of Pink Lady and Fuji Seedlings

Sunday, July 26, 2009
Illinois/Missouri/Meramec (Millennium Hotel St. Louis)
Julia M. Harshman, Plant Sciences and Landscape Architecture, University of Maryland, College Park, MD
Christopher Walsh, Univ of Maryland, College Park, MD
This project was initiated in 1991 with an open pollination of McIntosh Wijcik by Gala to produce an initial population of compact seedling trees. The goal was to incorporate the precocity of Gala into a short-statured, spur-type tree.  Precocious seedlings from the original cross that were tolerant to late-spring freezes were selected at Keedysville, MD.  Field tolerance to fireblight was also evaluated following summer hailstorms. First generation trees were then hybridized with commercial cultivars such as Pink Lady, Fuji, Braeburn, Commander York and Red Yorking that are adapted to hot, humid climates. Seedlings from the crosses were germinated and initially evaluated in the greenhouse and set in the field. In January 2008 (at the end of the 5th leaf) trees were sorted by phenotype. Approximately 90% of the wild-type trees were then removed, but all of the columnar trees were retained.  The Pink Lady and Fuji populations were evaluated for bloom in April, and tree height, tree spread and fireblight in June. After a series of hailstorms in August, the number of fireblight strikes per tree was counted. Harvest and fruit analysis was conducted weekly from September 5th until October 10th. The data recorded for a representative sample of the fruit included weight, height, width, soluble solids, firmness, ground color, red color and starch.                   From the tree size data measurements, the compact populations of Pink Lady and Fuji trees had different tree architecture, but only a slight difference in precocity when compared with their wild-type populations. The wild-types for both Fuji and Pink Lady had a height to spread ratio of about 1.4. Compact Pink Lady trees had an average height to spread ratio of 3.38 while the compact Fuji trees had a ratio of 3.92. Fireblight strikes per tree were similar for both populations. Fruit for both compact populations were heavier, but the length-to-diameter (L/D) ratios were identical. Soluble solids were comparable, with a slight but measureable difference in fruit firmness.  Fruit from wild-type trees in both cultivars was slightly smaller and firmer. Using the data and taste-test notes made while performing the fruit analysis, elite selections from these Pink Lady and the Fuji populations were identified. We expect to have clones available for commercial trials by 2010.