PRI Disease Resistant Apple Breeding Program

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Williams' Pride
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HortScience 140:551-552. August 1979.

'Jonafree' Apple1

D. F. Dayton and J. B. Mowry

Department of Horticulture, University of Illinois, Urbana, IL 61801

E. B. Williams1, Jules Janick3, and F. H. Emerson3

Purdue University, West Lafayette, IN 4 790 7

L. F. Hough and Catherine Bailey

Department of Horticulture and Forestry, Rutgers, The State University, New Brunswick, NJ 08903

Additional index words: Malus spp., fruit breeding, disease resistance

1Received for publication March 26, 1979. This research was partially supported by funds from the Illinois Agricultural Experiment Station and from the Purdue University Agricultural Experiment Station. Journal Paper No. 7568 of the Purdue University Agricultural Experiment Station. Paper of the journal series of Cook College, Department of Horticulture and Forestry, Rutgers, The State University.
The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper must therefore be hereby marked advertisement solely to indicate this fact.
2Department of Botany and Plant Pathology.
3Department of Horticulture.

'Jonafree' is an attractive red apple (Malus domestia Borkh) with field immunity to apple scab incited by Venturia inaequalis (Cke) Wint. The fruit is of medium size and matures with 'Jonathan'. It is released as a potential commercial cultivar with strong resemblance to 'Jonathan' in many major horticultural characters in addition to its similar maturity date.

'Jonafree' is the 5th apple cultivar (1, 2, 3, 4) developed by the cooperative apple breeding program of the Illinois, Indiana, and New Jersey Agricultural Experiment Stations. It appears best adapted to those climatic regions which favor good development of 'Jonathan'. The attractive glossy red fruit closely resembles 'Jonathan' in size and shape (Fig. 1). The medium red overcolor covers up to 95% of the fruit surface, but when allowed to become full ripe on the tree does not develop the very dark red characteristic of some 'Jonathan' strains.

Fig. 1. Fruits of 'Jonafree'

The skin is moderately thick and tough, very similar to 'Jonathan'. The flesh is pale yellow, fine grained, crisp and juicy. Fruits directly from the tree at maturity are somewhat less acid than 'Jonathan', but with a rich and slightly aromatic flavor. The dessert quality is classified as very good.

Fruit of 'Jonafree' in ordinary storage at 0.5-1.0°C hold texture and flavor up to 10 weeks. Shriveling due to moisture loss, even without humidification, does not occur. "Jonathan spot" or similar disorders, even on very overripe fruits or after long storage, have not been observed.

While field immune to apple scab, 'Jonafree' appears slightly susceptible to apple mildew incited by Podosphaera leucotricha (Ell. & Eu.) Salm., but networks of russet on the fruit have not been observed. The few fireblight infections incited by Erwinia amylovora (Burrill) Winslow et al. observed on new shoots failed to advance into older wood, indicating much lower susceptibility than 'Jonathan'.


The original seedling tree was planted in 1965 in a breeding orchard of the Illinois Agricultural Experiment Station, Urbana, Illinois. The seedling resulted from crossing an earlier seedling selection 855-102 as seed parent with New Jersey 31 as pollen parent. The complete pedigree is shown in Fig. 2. It was selected on the basis of its fruit characteristics in 1972. Propagated trees have been and are under test, as Coop 22, at the cooperating agricultural experiment stations and at several locations in the respective states.

Pedigree of Co-op 22

Fig. 2. Pedigree of 'Jonafree' apple.


The tree is vigorous and sets heavy annual crops, indicating that thinning may be necessary in years when pollination conditions are favorable. The growth habit is moderately spreading, not a "spur type", but the fruit is borne almost entirely on spurs. Spur production on grafted trees is heavy, and grafted trees have been as precocious as 'Jonathan' is bearing. It appears compatible on Malling (M) 7 and M 9 rootstocks.

The following detailed description follows Zielinski (5), and uses color designations according to the 1966 Royal Horticultural Society Colour Chart, issued by the Royal Horticultural Society of London.


  • Pedicel: 1.3 cm in length
  • Corolla: 3.7 cm in diameter at anthesis
  • Color: (bud) red-purple, plate 61C (open) upper side white to very pale red purple, plate 691); lower side red-purple, plate 64D


  • Shape: roundish to slightly roundish-oblate
  • Size: axial diameter 5.5 - 7.0 cm -1 transverse diameter 6.3 - 7.6 cm.
  • Color: undercolor yellow green, plate 145C to yellow, plate 2C; overcolor 75 - 95% medium red, without stripes, plates 45C to 46A.
  • Skin: smooth with dry wax and with small light tan dots; dots are sunken or flush with skin surface; skin moderately thick, moderately tough. No general russeting.
  • Stem: average 1.5 cm, usually with abscission point even with or only slightly above shoulders of the fruit. Medium thickness and medium stiffness. Stem inserted in cavity vertically or at only a very slight angle.
  • Cavity: acute, deep, medium width, not russeted.
  • Basin: abrupt, medium width and depth.
  • Calyx: persistent, closed, lobes erect or only slightly recurved.
  • Calyx tube: urn shaped, closed.
  • Stamens: median.
  • Core lines: clasping, turbinate.
  • Core: median, closed, small.
  • Carpels: ovate, mucronate, smooth. Seeds: acute, not tufted.
  • Flesh: fine grained texture, crisp and slightly tough until full ripe, juicy, light yellow, plate 13D; sub-acid, moderately rich flavor, slight and pleasant aroma.
  • Maturity season: with 'Jonathan'.
  • Storage characteristics: texture and flavor retained for 10 weeks at 0.5 - 1.0°C, without development of "Jonathan spot" or similar disorders.
  • Use: very good dessert apple.


  • Growth habit: semi-spreading, vigorous. Fruiting habit: non-spur type".
  • Bark: medium brown on 1-yr shoots, light brown on 2-yr and older branches. Surfaces relatively smooth with light tan lenticels. Surface of new shoots heavily pubescent.
  • Leaf shape: simple, not lobed, elliptic with compound serrate margins; marginal serrations blunt to slightly rounded on vigorous shoots; on spur leaves and those on weak shoots marginal serrations are acute.
  • Leaf aspect: upper leaf surfaces slightly rugose on vigorous shoots; on spurs and weak shoots upper leaf surfaces are smooth. All leaves heavily pubescent.


Propagation material for test purposes is available to state and federal agricultural experiment stations. Trees will be available from qualified nurseries. An application for a plant patent has been filed.

Literature Cited

  1. Dayton, D. F., 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 scab. Fruit Vars. Hort. Dig. 24:20-22.
  2. De Courtye, L. M., E. B. Williams, J. Janick, F. H. Emerson, D. F. Dayton, J. B. Mowry, L. F. Hough, and Catherine H. Bailey. 1974, 'Priam' apple. Hort. Science 9:401-402.
  3. Williams, E. B., J. Janick, F. H. Emerson, D. F. Dayton, J. B. Mowry, L. F . Hough, and Catherine H. Bailey. 1972. 'Priscilla', a fall red apple with resistance to apple scab. Fruit Vars. Hort. Dig. 26:35.
  4. Williams, E. B., J. Janick, F. H. Emerson, D. F. Dayton, J. B. Mowry, L. F. Hough, and Catherine H. Bailey. 1975. 'Sir Prize' apple. HortScience 10:281-282.
  5. Zielinski, Q. B. 1955. Modern systematic pomology. Wm. C. Brown, Dubuque, Iowa.

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