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Abstract
The general trend to higher tree density in apple orchards has been almost totally dependent on the use of the size-controlling rootstocks with more dwarfing rootstocks required as the tree density increased. With the use of such rootstocks becoming common in commercial orchards and the continued evaluation by researchers, a number of problems have become apparent including poor anchorage; greater susceptibility to winter injury, drought or “wet feet”, root rot, crown rot and fireblight; and graft incompatibility. In the case of peaches, nectarines, and other stone fruits, the lack of satisfactory size controlling rootstocks has dampened the trend to high density as observed in apple plantings. Several peach rootstocks have been evaluated and may show promise for increased hardiness or other beneficial effects but none have more than a minimal effect on size control.
Abstract
Imposing stress on branches of white pine (Pinus strobus L.), apple (Pyrus malus L.), and peach (Prunus persica Sieb. and Zucc.) trees by tying them in arcs resulted in increases in the ethylene content of the internal atmospheres of the stressed branches.
Abstract
‘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.
Abstract
‘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.
Abstract
‘Jonafree’ is an attractive red apple (Malm 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.
Abstract
Apple scab, caused by the fungus Venturia inaequalis (Cke.) Wint. is one of the most economically important apple diseases, because of the annual loss of marketable fruit, tree debilitation as a result of foliage destruction, and the cost of chemicals, equipment, and labor for its control. Infection can occur at any time during the growing season in humid apple-producing areas of the world. Most scab control programs must be based on the application of 5 to 15 or more protective fungicide sprays from the beginning of bud break to harvest. Estimates of direct costs for scab control including fungicides, equipment costs, and labor range from 20 to 30¢ per bushel or some 10% of the annual cost of production. In addition, chemical control must be exacting with application of spray materials most efficacious in rainy spring weather it is oftne difficult to move equipment through the orchard.
Abstract
‘Williams’ Pride’ is an early-maturing, attractive, dark red apple (Malus × domestica 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 midwestern 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.
Abstract
‘McShay’ is an attractive, excellent quality apple (Malus × domestica Borkh.) with field immunity to apple scab. The fruit is similar in color, flavor, and texture to ‘McIntosh’. ‘McShay’ is named in honor of the late J. Ralph Shay and is a late fall dessert apple well-adapted to Oregon's Willamette Valley. ‘McShay’ is the ninth cultivar to be released by the cooperative apple breeding program of Indiana, Illinois, and New Jersey Agricultural Experiment Stations.
Abstract
‘Priam’ is a new fall red apple with resistance to apple scab caused by Venturia inaequalis (Cke.) Wint. ripening close to ‘Jonathan’ and about one week before ‘Delicious’ (Fig. 1).