The World of Apples

Apple varieties, United States

Keepsake

A hard, long-keeping Minnesota apple from a 1936 cross, introduced in 1979; DNA shows it is a parent of Honeycrisp

History

Keepsake comes from a cross of MN 447 with Northern Spy, made at the University of Minnesota in 19361,2. The seedling was selected in 1947, tested as MN 1593 and introduced in 19791,2; Luby’s 1991 list of the University’s introductions gives the same parents for Sweet Sixteen, introduced in 19782. MN 447 was entered in the records as a seedling of open-pollinated Malinda1,2; the University now markets it under the trade mark Frostbite, naming it as a parent of Keepsake6. Howard and colleagues give Keepsake’s parents as Northern Spy and Frostbite3. They report that Frostbite was first selected in 1922 and released in 2008, that marker data rule out Malinda as its parent, and that it is probably a grandchild of Duchess of Oldenburg3.

DNA has shown Keepsake to be a parent of Honeycrisp. Honeycrisp’s recorded parents, Macoun and Honeygold, proved wrong when tested with DNA markers; a study with 11 SSR markers identified Keepsake as one parent, and in 2017 Howard and colleagues confirmed it with 3,435 SNPs and identified the other as MN1627, a University selection from Duchess of Oldenburg × Golden Delicious, now thought to be extinct3. Their pedigree, including Keepsake’s own parents, showed no inheritance errors3.

Keepsake trees are sold by many nurseries that support the Minnesota Nursery Research Corporation4.

The fruit

The fruit is 5.7 to 7.0 cm across, irregular in shape and about 90 per cent red; the USDA’s germplasm inventory calls it unattractive1. The light yellow flesh is fine-grained, very hard, crisp and juicy1,5, with an aromatic flavour that the University describes as exotic, sweet and spicy1,5. The fruit mellows in store and is at its best for eating in January or February1. It keeps until April according to the USDA inventory, or for about six months according to the University1,5. It ripens from mid-October to mid-November, depending on where it is grown; the University gives mid-October1,5.

Growing

The tree is spreading and of moderate vigour, and easy to manage1,5. It resists fire blight and cedar-apple rust1. It is hardy throughout Minnesota and withstands −40 °C (“-40 degrees F”), though the fruit may not ripen in the state’s northernmost counties1.

Uses

The University rates it good for eating fresh and for cooking5.

Where the sources disagree

  • Malinda as a grandparent. The University gives MN 447, sold as Frostbite, as a seedling of open-pollinated Malinda1,2,6; Howard and colleagues report that marker data rule out Malinda as Frostbite’s parent3.

Family tree

Parents, grandparents and great-grandparents, as the entries in the atlas record them.

  • Keepsake United States, 1936
    • Parent MN 447
    • Parent Northern Spy United States, about 1800

Offspring in the atlas

11 varieties in the atlas descend from Keepsake.

Sources

  1. Plant Inventory No. 204, Part II, pp. 116–117: Keepsake (PI 589894), R. A. Norris (ed.), U.S. Department of Agriculture, Agricultural Research Service, 1996. Supports: developed by the University of Minnesota; pedigree "MN 447(o.p. Malinda) x Northern Spy"; cross made 1936; selected 1947; introduced 1979; tested as Mn 1593; "Unattractive, irregularly shaped", 2.25–2.75 inches in diameter, 90% red; flesh fine-grained, very crisp, juicy, light yellow; aromatic flavour; "Mellows with age", peak fresh eating quality in January or February; keeps in storage through April; ripens mid-October to mid-November, depending on location; tree moderately vigorous, spreading; resistant to fire blight and cedar-apple rust; hardy throughout Minnesota but may not mature in the northernmost counties; "Withstands temp. -40 degrees F.".
  2. Breeding cold-hardy fruit crops in Minnesota, J. J. Luby, HortScience 26(5): 507–512 (copy on a University of Wisconsin–Madison site), 1991-05. Supports: Table 1, "Fruit cultivars introduced by the Univ. of Minnesota (1908-88)" (p. 509): Keepsake, Minnesota no. 1593, introduced 1979, parentage "MN 447 (Malinda op) x Northern Spy"; Sweet Sixteen, introduced 1978, with the same recorded parentage.
  3. Elucidation of the 'Honeycrisp' pedigree through haplotype analysis with a multi-family integrated SNP linkage map and a large apple (Malus × domestica) pedigree-connected SNP data set, N. P. Howard and others, Horticulture Research 4: 17003, 2017. Supports: the recorded parentage of Honeycrisp, Honeygold × Macoun, shown incorrect by SSR markers; Keepsake identified as one parent with 11 SSR markers and verified with 3,435 SNPs; the other parent the unreleased University selection MN1627 (Duchess of Oldenburg × Golden Delicious), no longer available and thought to be extinct; Keepsake's parents given as Northern Spy and Frostbite; the pedigree free of Mendelian-consistent and Mendelian-inconsistent errors across all SNPs evaluated; Frostbite "originally selected in 1922" and "released in 2008", thought to come from open-pollinated Malinda seed, but Malinda "determined to not be the parent"; it is likely a grandchild of Duchess of Oldenburg.
  4. Apple licensing & commercialization, Minnesota Hardy, University of Minnesota. Supports: Keepsake trees available at many nurseries and supported by Minnesota Nursery Research Corporation participants.
  5. All University of Minnesota Apple Varieties, Minnesota Hardy, University of Minnesota. Supports: Keepsake: "Very hard and crisp with yellow flesh and an exotic sweet, spicy flavor"; good for fresh eating and cooking; stores for 6 months; tree of medium vigour and easy to manage; ripens mid-October.
  6. Frostbite, Minnesota Hardy, University of Minnesota. Supports: the Frostbite apple, "MN447 variety", Frostbite a registered trade mark of the Regents of the University of Minnesota; Frostbite "a parent to Keepsake and Sweet 16 apples and a grandparent to Honeycrisp"; its origin given as "Malinda open pollinated".

All 235 varieties from United States