Fruit Varieties and Horticultural Digest, January 1970
Prima an Early Fall Red Apple with Resistance to Apple Scab1
D. F. Dayton and J. B. Mowry,2
L. F. Hough and Catherine H. Bailey,3
E. B. Williams, Jules Janick, and F. H. Emerson4
1Published with the approval of the Illinois Agricultural Experiment Station; paper of journal series of the New Jersey Agricultural Experiment Station and Journal No. 3905 of the Purdue Agricultural Experiment Station, Lafayette, Indiana.
'Prima' is a new, red apple cultivar introduced from a cooperative breeding program carried out by the Agricultural Experiment Stations of Illinois, New Jersey, and Indiana, and informally cooperative with a number of other states and countries. The program was initiated in 1945 by J. R. Shay, then of Purdue University, and L. F. Hough, then of the University of Illinois. As the name implies, 'Prima' is the first cultivar to be released under this cooperative effort. The prefix PRI in the name is an acrostic formed from the three institutions involved, viz., Purdue, Rutgers, Illinois. The apple was formerly designated as Co-op 2 and by its breeding number 1225-100 (3). The selection at present is widely planted under the Apple Breeders Cooperative testing program.
The original seedling was planted in 1958 in the breeding orchard of the Department of Horticulture at the Illinois Experiment Station, Urbana, Illinois. It was produced from crossing the seedling 14-510 as the seed parent and the selection, N.J. 123249, as the pollen parent in 1957. The complete pedigree is shown in Fig. 1. 'Prima' is heterozygous for a dominant genetic factor Vf inherited from Malus floribunda 821 which causes it to be highly resistant to the apple scab organism, Venturia inaequalis (Cke.) Wint., and will only rarely show any evidence of infection (2). The origin of the resistant clone, F-226829-2-2, dates from crosses made early in this century by Dr. C. S. Crandall at the University of Illinois (1).
Figure 1. Pedigree of Prima.
The cultivar first fruited in August, 1963. The fruit has since been examined from topworked or grafted trees at Urbana and Carbondale, Illinois; Lafayette, Indiana; New Brunswick, New Jersey and Sturgeon Bay, Wisconsin.
The tree is spreading and vigorous. It flowers in midseason, a few days before 'Golden Delicious.' The tree shows field resistance to fireblight and apple blotch.
'Prima' has excellent dessert quality, texture, and flavor. The attractive fruits have a yellow round color with 60-80 percent bright red over-color principally as a blush (Fig. 2). They ripen about 3 weeks before 'Jonathan' or a month before 'Delicious.' There is little tendency for the fruits to drop before maturity. The characteristic rich flavor and crisp texture is retained a month or more at 34°F. The following detailed description of the flower and fruit follows Zielinski (4) and uses the color designations according to the Horticultural Chart used by the British Colour Council in collaboration with the Royal Horticultural Society.
Fig. 2. Fruits of 'Prima'
'Prima' is expected to be adapted to the Midwest and northern areas. Trees will be available from qualified commercial nurseries. Application has been filed for a public use patent.