PRI Disease Resistant Apple Breeding Program

Co-op 1
Co-op 3
Sir Prize
Co-op 6
Co-op 7
Co-op 8
Co-op 9
Co-op 10
Co-op 11
Co-op 12
Co-op 14
Co-op 15
Co-op 16
Co-op 17
Co-op 18
Co-op 19
Co-op 20
Williams' Pride
Co-op 24
Scarlett O'Hara
Co-op 26
Co-op 27
Co-op 28
Pixie Crunch
Co-op 34
Co-op 35
Co-op 36
Co-op 37
Co-op 40
Co-op 41
Co-op 42
Co-op 44

HortScience, VOL. 10(3), June 1975

'Sir Prize' Apple1

E. B. Williams2, Jules Janick3, F. H. Emerson3, D. F. Dayton4, J. B. Mowry4, L. F. Hough5, and C. H. Bailey5

Purdue University, West Lafayette, Indiana

1Received for publication January 17 , 1975. Journal Paper No. 5793 of the Purdue University Agricultural Experiment Station, West Lafayette, Indiana, and paper of the journal series of Cook College, Department of Horticulture and Forestry, Rutgers - The State University, New Brunswick, New Jersey.
2Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana.
3Department of Horticulture, Purdue University, West Lafayette, Indiana.
4Department of Horticulture, University of Illinois, Urbana, Illinois.
5Department of Horticulture and Forestry, Rutgers University, The State University of New Jersey, New Brunswick, New Jersey.

'Sir Prize' is a yellow, russet-free apple with immunity to apple scab caused by Venturia inaequalis (Cke.) Wint. The fruit is large and ripens along with 'Golden Delicious'. It is released as a home garden cultivar.

'Sir Prize' is the fourth apple cultivar (1, 2, 3) to be introduced from the cooperative breeding program carried out by the Agricultural Experiment Stations of Indiana, Illinois, and New Jersey and informally cooperative with a number of other states and countries. The prefix PRI in the name is an acronym formed from the three institutions involved, viz. Purdue, Rutgers, and Illinois. The apple has been widely tested in the United States and Europe and appears well adapted to the United States Midwest. The large attractive fruit has waxy skin that does not shrivel in storage (Fig. 1). The flesh is juicy and very tender with excellent dessert quality. Notwithstanding its unusually high quality and attractive appearance, its thin skin and bruise susceptibility make it unsuitable for commercial orchards under present handling and grading practices. Although unsuited for commercial use, its outstanding fresh fruit qualities, steady productiveness, and disease resistance make it desirable for home gardens.

Fig. 1. 'Sir Prize' apple.


The original seedling was planted in 1955 in the breeding orchards of the Purdue University Agricultural Experiment Station, Lafayette, Indiana. It was produced by crossing the seedling 14-152 as the pollen parent and 'Doud's (2-4-4) Tetraploid Golden Delicious' as the seed parent. The complete pedigree is shown in Fig. 2. The seedling first fruited in 1961 and subsequently has been tested as grafted trees in various locations under the designation Co-op 5.

Pedigree of Co-op 5

Fig. 2. Pedigree of 'Sir Prize' apple.


The tree is vigorous and produces good annual crops. It seldom requires thinning. The tree is immune to apple scab, and moderately resistant to powdery mildew and cedar apple rust. Trees have shown little fireblight.

The tree has typical triploid characteristics including large leaves and flowers and sturdy, vigorous growth. Despite low seed production, fruit set is good with little tendency for biennial bearing. Pollen viability probably is low, thus 'Sir Prize' should not be used as a pollinator.

The following detailed descriptions of the flower and fruit follows Zielinski (4) and uses the color designations according to the Horticultural Chart issued by the British Colour Council in collaboration with the Royal Horticultural Society.


  • Pedicel: 3 cm (1 1/4 in.) in length
  • Corolla: 5 cm. (2 in.) in diam at anthesis
  • Color: Magenta, ranging from plate 27 (tight buds) to 27/3 and paler in open flower


  • Shape: Uniform ovate to conic, slightly ribbed
  • Size: Axial diam 7.6 to 8.3 cm (3 to 3 1/4 in.), transverse diam 7.6 to 8.3 cm (3 to 3% in.)
  • Color: Overall Lemon yellow (plate 4/2), sometimes with a slight red blush
  • Skin: Very smooth, waxy With scattered small To medium dots, thin
  • Cavity: Acute, medium depth and width, russeted
  • Basin: Medium to deep, breadth medium to broad
  • Calyx tube: Urn-shaped
  • Stamens: Basal
  • Core lines: Meeting
  • Core: Medium, closed, small
  • Carpels: Cordate, smooth
  • Seeds: Acuminate, not tufted
  • Flesh: Fine grained texture, tender, juicy; excellent quality, sub-acid, rich flavor; lemon yellow color (plate 4/3); pleasant and distinctive aroma
  • Maturity season: 'Golden Delicious' season, 4 weeks after 'Prima'
  • Keeping quality: Very good through winter season
  • Use: Excellent dessert apple


Budwood is available for test purposes to Federal and State Agricultural Experiment Stations. Trees will be available from qualified nurseries. Application has been filed for a plant patent.

Literature Cited

  1. D. F. Dayton, J. B. Mowry, L. F. Hough, Catherine H. Bailey, E. B. Williams, J. Janick, and F. H. Emerson. 1970. 'Prima' - an early fall red apple with resistance to apple scab. Fruit Vars. Hort. Dig. 24:20-22.
  2. E. B. Williams, J. Janick, F. H. Emerson, D. F. Dayton, J. B. Mowry, L. F. Hough, and Catherine Bailey. 1972. 'Priscilla', a fall red apple with resistance to apple scab. Fruit Vars. Hort. Dig. 26:34-35.
  3. L M. Decourtye, E. B. Williams, J. Janick, F. H. Emerson, D. F. Dayton, J. B. Mowry, L. F. Hough, and Catherine Bailey. 'Priam' apple. HortScience 9:401-402.
  4. Q. B. Zielinski. 1955. Modern systematic pomology. Wm. C. Brown Co., Dubuque, Iowa.

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