HortScience 16(6):798-799. December 1981.
E. B. Williams,2 Jules Janick,3 and F. H. Emerson3
Purdue University, West Lafayette, IN 47907
D. F. Dayton
Department of Horticulture, University of Illinois, Urbana, IL 61801
L. F. Hough and Catherine Bailey
Department of Horticulture and Forestry, Rutgers - The State University, New Brunswick, NJ 08903
Additional index words. Malus domestica. Venturia inaequalis. disease resistance, fruit breeding
1Received for publication July 15. 1981. Journal Paper No. 8656 of the Purdue 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.
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.
2Department of Botany and Plant Pathology.
3Department of Horticulture.
'Redfree' is an attractive high finish red apple (Malus domestica Borkh.) with field immunity to the apple scab organism Venturia inaequalis (Cke.) Wint). The fruit is medium size. It matures 2 to 3 weeks before 'Prima' and 1 week before 'Paulared'. 'Redfree' is released as a potential commercial cultivar for use as a summer dessert apple.
'Redfree' is the 6th apple cultivar (1, 2, 3, 4, 5) developed by the cooperative apple breeding program (PRI) of Illinois, Indiana and New Jersey Agricultural Experiment Stations. This apple has been widely tested in the United States and in Western Europe. It appears to have broad climatic adaptation. It is unique in summer apples in that it has firm flesh and can be held in storage up to 2 months without loss of quality or firmness. The attractive glossy red fruits (Fig. 1) do not drop easily and will remain firm and retain quality on the tree up to two weeks after maturity. Ripening is somewhat uneven and may require more than one picking.
Fig. 1. Fruits of 'Redfree' apple.
Fruit of 'Redfree' have a smooth glossy skin with 80-90% medium washed to slightly striped red on a yellow ground. The flesh is light cream. medium grained, crisp, juicy. and mild subacid. Dessert quality is good for season.
In addition to field immunity to scab, 'Redfree' appears to be immune to cedar apple rust, incited by Gymnosporangium juniperi-virginianae Schw. It has moderate to good resistance to fire blight incited by Erwinia amylovora (Burr.) Winslow et al. and powdery mildew incited by Podosphaera leucotricha (Ell. & Ev.) Salm., and has shown little response to the European red mite (Panonychus u1mi Koch). It is a good pollinizer with most selections tested.
The original seedling was planted in 1966 in a breeding orchard of the Indiana Experiment Station, Lafayette, Indiana. The seedling resulted from crossing an earlier scab immune seedling selection, PRI 1018-101, as pollen parent and 'Raritan' as seed parent.
The complete pedigree is shown in Fig. 2. It was selected on the basis of pomological characteristics in 1971. Propagated trees have been under test as Coop 13 at cooperating Experiment Stations in several states.
Fig. 2. Pedigree of 'Redfree' apple.
The tree is somewhat upright and sets average annual crops. Thinning is usually not necessary. It has been shown to be compatible on Malling 7, 26 and Malling-Merton 111 rootstocks.
The following detailed description follows Zielinski (6) and uses color designations according to the Royal Horticultural Society Colour Chart, issued by the Royal Horticultural Society of London.
Budwood is available only for test purposes at Federal and State Experiment Stations. Trees will be available from licensed nurseries. Plant Patent #4322 has been granted for this cultivar.