Disease resistance does not mean total freedom from pesticides, since none of these cultivars are immune to insect damage or summer diseases like sooty blotch or flyspeck. There are some new cultivars coming from Germany that will have multiple resistances to such diseases as powdery mildew and fire blight, among others. These are being marketed as "ReZista Series."
Earlier releases such as Prima and Priscilla were not well accepted because of poor fruit quality. Since their release, newer cultivars now available may have promise for commercial orchards. Following are comments on selected apple-scab-resistant cultivars:
Crimson Crisp (Co-op 39) was named by the Purdue Rutgers Illinois (PRI) cooperative breeding program. The medium to dark red fruit have a cream-colored, mildly acidic, coarse flesh. The fruit will store about 6 months in regular storage. In addition to apple scab, Crimson Crisp is moderately resistant to rusts and powdery mildew. It is susceptible to fire blight. Fruit mature around the middle to end of September and hang well on the tree.
Crimson Gold was originally tested as Svatava from the Czech Republic. While resistant to scab it is slightly susceptible to powdery mildew and susceptible to fire blight. Fruit are medium size with fine texture, juicy, and have a good acid balance. Fruit ripen just before Golden Delicious. Storage life is 7 to 8 months. Variety may not be suitable for more northern areas of Pennsylvania, as it has been reported to produce better under warmer conditions.
Crimson Topaz was developed in the Czech Republic from a cross between the Czech apple cultivars Vanda and Rubin. Topaz is a medium to medium-large apple. The skin color is yellow overlain with a red and crimson flush. The flesh is crisp and cream colored. The trees are moderately vigorous and very precocious. Trees are resistant to apple scab and moderately resistant to powdery mildew. Fruit mature about 1 week after Golden Delicious.
Enterprise (Co-op 30) was released by the PRI program as a later-maturing, scab-resistant apple cultivar. Flesh is yellow, with a 75 percent red skin. Fruit are of good quality. Flavor is very good although on the tart or acid side. Enterprise matures around October 15 in south-central Pennsylvania and about a week later in central Pennsylvania. The tree has a very vigorous growth habit. It is suggested for both homeowner and commercial trials. It is believed prone to corking, but this has been controlled in south-central Pennsylvania plantings with standard calcium chloride programs.
Freedom (NY58553-1) is ready for harvest around the end of September. Fruit are large and their external appearance is not very good, having a rough-looking finish. This cultivar does not store well, having ripened unevenly on the tree. Suggested for home plantings only.
Galarina™ is a Gala-like apple that is resistant to apple scab and can be stored for longer periods. It was developed in France from a Gala and Florina cross. The medium-size fruit matures 1 to 2 weeks after Gala. The skin color is 65 to 100 percent orange red over greenish yellow with flesh that is yellowish white. The flavor is aromatic and slightly tart. Trees are moderately vigorous.
GoldRush (Co-op 38) was released by the PRI program and is resistant to apple scab. The tree is moderately vigorous with an upright growth habit. The fruit ripen very late. Its growing season may be too long to be planted from central Pennsylvania northward. Fruit quality is excellent, and fruit has an approximately 7-month storage period. Fruit are medium to large and have a spicy to slightly acid taste at harvest, becoming better after a period of 2 months in storage. GoldRush produces a very good single blend hard cider.
Jonafree ripens with Jonathan and has a 95 percent red overcolor much like Jonathan's, but it is less susceptible to fire blight and powdery mildew than Jonathan. Jonafree is a very hard apple that does not develop a good flavor until after a period of storage. This cultivar has very vigorous growth and tends to be a tip bearer as well as an alternate year bearer. May be suitable for processing.
Liberty (NY55140-19) is dark red and resistant to rusts, mildew, and fire blight. Its harvest date is the last week in September to the first week in October in central Pennsylvania. The fruit tends to be small and may require multiple pickings; flavor is better after storage. Japanese beetles and European apple sawfly favor this cultivar to the extent that extra sprays are needed to control the pests. It is not recommended for southern Pennsylvania due to high summertime temperatures affecting fruit color and quality.
Novamac is a McIntosh type released from Kentville, Nova Scotia. In plantings at Rock Springs on M.9 rootstocks, the trees have been very precocious and have been consistent croppers. The fruit look and taste like McIntosh. This cultivar holds promise for both backyard and commercial use in areas where McIntosh is grown. Mid-season harvest. Severe preharvest fruit drop.
Nova Spy was developed in Nova Scotia as a scab-resistant "Spy-type" apple. It is a juicy, firm-fleshed red apple. It is moderately susceptible to rusts and only lightly susceptible to powdery mildew. It was developed in Canada from a cross between Nova Easygro and NY-44411-1. The fruit are attractive, moderate high quality, long keeping, and similar to Northern Spy. Fruit are medium in size, globose conical, and slightly ribbed. The flesh is creamy yellow, fine, very firm, crisp, and juicy. The fruit mature between Delicious and Northern Spy. It is an excellent processing cultivar. The tree is upright and moderately vigorous.
Otava was developed in the Czech Republic from a cross between Sampion and Jolana. The globose and ribbed fruit mature with Golden Delicious and have yellow skin with a slight red-orange blush. The flesh is yellow to cream with fine-grained texture, juicy, and has a sweet subacid flavor. It is resistant to apple scab and tolerant to powdery mildew.
Pixie Crunch™ (Co-op 33) was released from the Purdue, Rutgers, and Illinois cooperative breeding program. The blushed dark red to purple fruit have a yellow flesh that is extremely crisp, medium to fine grained, and juicy. Storage life is at best 2 months. The flavor is moderately to mildly acid. Fruit size tends to be small (2.5 inches in diameter), which may decrease its value as a commercial cultivar. It is immune to apple scab, susceptible to powdery mildew, and moderately susceptible to fire blight. Early, mid-season harvest.
Pristine™ (Co-op 32) was released from the PRI breeding program. It is also moderately resistant to fire blight, slightly resistant to cedar apple rust, and resistant to powdery mildew. Fruit mature with Lodi and can be used as a replacement for Lodi. Plantings have been very productive. Fruit color is green to yellow.
Querina is also known as Florina and was developed in France. Fruit size is similar to Empire. Tree is moderately susceptible to powdery mildew and tolerant of fire blight. Matures about 2 weeks after Goldens.
Redfree is a red-skinned summer apple. Harvest is around the middle of August in central Pennsylvania (6-7 weeks before Delicious). Storage life is only about 2 months. Redfree shows moderate tolerance to fire blight and powdery mildew. Tree wood is very brittle and weak. It tends to be a tip bearer like Rome Beauty. Suggested only for roadside markets.
Rubinola is resistant to apple scab and powdery mildew and matures 10 days before Golden Delicious. The trees are vigorous. The cultivar was the result of a cross between Prima and Rubin. The fruit are medium to large, flat, globose, and with a skin that is bright red over most of the surface, although some russeting can occur. The flesh is yellow, firm, fine textured, juicy, and has a sweet aromatic flavor.
Scarlet O'Hara™ was released from the PRI cooperative breeding program. It was previously tested as Co-op 25. It is a midseason red apple that ripens one week before Delicious. The fruit are round to slightly conic. The overcolor is described as 75 to 90 percent medium red to orange with a green yellow to yellow undercolor. The flesh is yellow to cream colored, firm, and crisp. The flavor is sweet to mildly subacid. The tree and fruit are field immune to scab, moderately resistant to powdery mildew, highly resistant to cedar apple rust, and highly susceptible to fire blight.
Sundance™ (Co-op 29) was released from the PRI cooperative breeding program. The pale yellow fruit are large and attractive. They have moderate stem-end russet. The flesh is medium to coarse cream colored with a very firm and crisp texture. The fruit have good storage potential and mature about 2.5 weeks after Delicious. Fruit taste best after about a month in storage. Sundance is moderately resistant to powdery mildew and highly resistant to cedar apple rust and fire blight.
Williams Pride is one of the earliest-ripening cultivars released from the PRI breeding program. It matures around the middle of August. The dark red fruit are large with a semi-tart flavor that is very good. The variety may have uneven ripening requiring multiple pickings. Growth observations indicate that the tree is very willowy. Suggested for homeowner use and roadside markets. Shows a strong tendency toward bitter pit.
WineCrisp™ (Co-op 31) was released as the nineteenth apple cultivar developed by the PRI cooperative breeding program. The fruit are a 100 percent dark red stripe with small lenticels. Fruit size is similar to Gala. Flavor is subacid to mild. Fruit firmness and the crisp texture are maintained in regular storage for an extended period. There is some tendency for fruit to drop when ripe. Needs a storage period of about about a month to obtain maximum quality. Field observations indicate the tree has good resistance to fire blight and moderate resistance to powdery mildew. It is susceptible to cedar apple rust. Tree growth is classified as vigorous.
Source: Penn State Tree Fruit Production Guide 2018-2019