PRI Disease Resistant Apple Breeding Program

 
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Prima
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Redfree
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Dayton
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HortScience 23(5):928-930. October 1988.

'Williams' Pride' Apple

Jules Janick1, Frank H. Emerson2, Paul C. Pecknold, and Jeffrey A. Crosby3

Purdue University, West Lafayette, IN 47907

Schuyler Safi Korban and Daniel F. Dayton4

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

Additional index words. Malus xdomestica, Venturia inaequalis, fruit breeding, disease resistance


Received for publication 10 Dec. 1987. Paper no. 11401 of the Purdue University Agricultural Experiment Station. This research was partially supported by funds of the Illinois Agricultural Experiment Station. We acknowledge the assistance of E.B. Williams, and J.M. Ingram (Purdue University), J.F. Morrisey (University of Illinois), S.A. Mehlenbacher and L.F. Hough (Rutgers University) in the development of 'Williams' Pride' apple. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.

1Department of Horticulture.
2Emeritus Professor, Department of Horticulture.
3Department of Botany and Plant Pathology.
4Emeritus Professor.


'Williams' Pride' is an early-maturing, attractive, dark red apple (Malus xdomestica Borkh.) with excellent fruit quality and field immunity to apple scab incited by Venturia inaequalis (Cke.) Wint. The fruit is of medium to large size and matures with the very earliest known commercial red cultivars in the midwestem United States. It ripens 1 week after 'Lodi' and 7.5 to 8 weeks before 'Delicious'. 'Williams' Pride' is released as a potential commercial cultivar for use as a summer dessert apple. The apple is named in honor of Edwin B. Williams, Emeritus Professor and long time leader of the disease-resistant apple breeding program at Purdue Univ.

'Williams' Pride' is the eighth apple cultivar (1-4, 6-8) developed by the cooperative breeding program of Indiana, Illinois, and New Jersey agricultural experiment stations. Fruiting has been observed for 9 years at the Purdue Univ. Horticultural Research Farm, and 3 years each at the Univ. of Illinois and Rutgers research facilities. It is now being tested in at least 35 locations throughout North America, Europe, Asia, and Africa. This summer apple is unique in that the flesh is very crisp and firm and that the fruit can be held in storage at least 6 weeks without loss in quality or firmness. The attractive, moderately bright, dark red fruit (Fig. 1) do not drop easily and retain firmness, crisp flesh texture, and flavor on the tree up to 2 weeks after maturity. During this time they develop nearly a 100% deep dark purple-red and heightened flavor, character, and juice content. Ripening is somewhat uneven and will require more than one picking.

Pedigree of Co-op 23

Fig. 1. Pedigree of 'Williams' Pride' apple.

Watercore has been observed in some years when fruits were allowed to hang until they were 100% dark red. Watercore of 'Williams' Pride' was severe in 1986 at Lafayette, Ind., when the disorder was common in other cultivars with this tendency, but was negligible in 1987.

Fig. 2 Fruits of 'Williams' Pride' apple

Origin

The original seedling, PRI 2845-1, was planted in 1975 in Block F of the Hinsley breeding orchard at the Purdue Univ. Horticultural Research Farm. This seedling was produced from crossing the seedling PRI 1018-101 as the seed parent and seedling N.J. 50 as the pollen parent in 1973 at Urbana, Ill. The complete pedigree is shown in Fig. 1. The seedling was selected in 1979 by E.B. Williams on the basis of pomological characters. Propagated trees have been under test as Co-op 23 at cooperating experiment stations in the United States and private growers in Indiana.

Description

Fruits of 'Williams, Pride' have moderately glossy skin with 75% to 90% medium washed and slightly striped dark red to purple-red on green-yellow to pale yellow ground. The lenticels are slightly recessed and inconspicuous. The flesh is light cream colored, medium grained, firm and crisp, very juicy, moderately subacid, slightly spicy, and full flavored. Dessert quality was judged to be excellent for the season in subjective evaluations.

The new cultivar produces a vigorous, spreading tree with sturdy growth, and good branch angles. Moderate to moderately heavy annual crops of moderate to large-sized fruits are produced without chemical or manual thinning. Fruits are borne on short spurs evenly distributed in the canopy. The tree has little blind wood and can be considered a semi-spur type. It is compatible on M.7a, M.26, and MM.111 rootstocks.

'Williams' Pride' has been extensively tested in the greenhouse for resistance to apple scab and in the field for resistance to the major apple diseases. Scab resistance is based on the complete absence of sporulation after repeated inoculation in the greenhouse with Races 1 through 5 of Venturia inaequalis using the methods of Williams (5), and complete absence of infection during 13 year's exposure in the field to natural inoculum pressures.

Field observations were made for nine successive seasons on 19 propagules planted in several locations. There was no evidence of infection by Gymnosporangium juniperivirginianae Schw. the fungus inciting cedar apple rust. The new cultivar has good to moderate resistance to fire blight incited by Erwinia amylovora (Buff.) Winslow et al. Only four fire blight strikes have been observed on two of the 19 propagules, one strike into second year growth in one season, and three strikes affecting only current year's growth in another season. 'Williams' Pride' has also shown moderate to good resistance to powdery mildew incited by Podosphaera leucotricha (Ell. & Ev.) Salm. A powdery mildew rating of 2, on a scale of 0 = no infection to 5 = most severe infection, was the most severe infection rating observed at West Lafayette, Ind. The base of vigorously growing shoots has shown the highest level of susceptibility; infection on leaves and terminals was rare. A low incidence of bitter-pitted fruits on vigorously growing 5-yearold trees in the 1986 season indicates that the cultivar may be slightly predisposed to this disorder. Leaf bronzing caused by parasitic mites has not been observed even in trees grown without miticides.

Bloom is annually very heavy, with a much extended bloom period. When compared with standard commercial cultivars, the duration of bloom extends from very early season to mid- or late mid-season. This character may provide avoidance of spring frost injury. On 22 to 23 Apr. 1986, the minimum temperatures at the Purdue Horticultural farm reached 7°C and reduced subsequent yields of 'Delicious' by 80%, of 'Jonathan' by 75%, and of 'Golden Delicious' by 60% while 'Williams' Pride' in adjacent blocks were reduced by <50%.

The following detailed description follows Zielinski (9) and uses color designations according to the Royal Horticultural Society Colour Chart.

FLOWER

  • Petals: 20 mm in length and 12 mm in width.
  • Corolla: 40 mm in diameter at anthesis.
  • Color: crimson from Plate 22/3 to 22/2 (bud); fading to white (open flowers).

FRUIT

  • Shape: oblate to round; uniform.
  • Size: axial diameter 64 mm; transverse diameter 74 mm.
  • Color: undercolor sap green (Plate 62/2); overcolor darkens to 90% ruby red (Plate 82/ 7); faint stripes on light side.
  • Skin: smooth, slightly waxy, with moderately conspicuous round, depressed lenticels; medium thick and tough; no russeting.
  • Stem: short, 10 to 15 mm, thick, and clubbed.
  • Cavity: acuminatc, deep, medium to narrow in width, smooth to very slightly russeted.
  • Basin: medium in depth, narrow in breadth with rounded sides; surface is irregular and wavy.
  • Calyx: persistent, closed, and recurved.
  • Calyx tube: conical.
  • Stamen remnants: marginal.
  • Core lines: clasping.
  • Carpels: emarginate.
  • Seeds: acuminate, not tufted.
  • Flesh: texture-medium to coarse, breaking, firm; quality-very good, excellent for season, mild subacid, rich flavor; color-Naples yellow (Plate 403/3); aroma-none to very faint.
  • Maturity season: 7.5 to 8 weeks before 'Delicious'.
  • Keeping quality: retains quality and texture for at least 6 weeks in refrigerated storage at 1°C.
  • Use: summer dessert apple.

TREE

  • Tree: spreading and vigorous, annual bearer.
  • Leaves: ovate, serrate, margin apex is acuminate, rounded base, length width ratio = 1.8.

Availability

Budwood is available only for test purposes at federal and state experiment stations. Trees will be available from licensed nurseries. Plant patent PP6268 was issued 6 Sept. 1988.

Literature Cited

  1. Dayton, D.F., I.B. Mowry, L.F. Hough, C.H. Bailey, E.B. Williams, J. Janick, and F.H. Emerson. 1970. 'Prima', an early fall apple with resistance to scab. Fruit Var. Hort. Dig. 24:20-22.
  2. Dayton, D.F., J.B. Mowry, E.B. Williams, J. Janick, F.H. Emerson, L.F. Hough, and C.H. Bailey. 1979. 'Jonafree' apple. HortScience 14:551-552.
  3. DeCourtye, L.M., E.B. Williams, J. Janick, F.H. Emerson, D.F. Dayton, J.B. Mowry, L.F. Hough, and C.H. Bailey. 1974. 'Priam' apple. HortScience 9:401-402.
  4. Korban, S.S., J. Janick, E.B. Williams, and F.H. Emerson. 1988. 'Dayton' apple. HortScience 23(5):927-928.
  5. William E.B. 1978. Handling the apple scab organism in the laboratory and greenhouse. Proc. Apple and Pear Scab Workshop. 11 July 1976. Kansas City, Mo. Amer. Phytopath. Soc. p. 16-18.
  6. William, E.B., J. Janick, F.H. Emerson, D.F. Dayton, J.B. Mowry, L.F. Hough, and C.H. Bailey. 1972. 'Priscilla' a fall red apple with resistance to apple scab. Fruit Var. Hort. Dig. 26:35.
  7. Williams, E.B., J. Janick, F.H. Emerson, D.F. Dayton, J.B. Mowry, L.F. Hough, and C.H. Bailey. 1975. 'Sir Prize' apple. HortScience 10:281-282.
  8. Williams, E.B., J. Janick, F.H. Emerson, D.F. Dayton, L.F. Hough, and C.H. Bailey. 1981. 'Redfree' apple. HortScience 16:798-799.
  9. Zielinski, Q.B. 1955. Modern systematic pomology. Brown, Dubuque, Iowa.

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