PRI Disease Resistant Apple Breeding Program

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Co-op 38

Fruit Grower February, 2000

Good As Gold

GoldRush is attracting lots of attention in the Midwest.

By Stella Naegely

Growers who plant the new scab-resistant variety, GoldRush, could be sitting on a gold mine. That is, once word gets out about the apple's excellent flavor, texture, and storage quality.

This Golden Delicious type was released in 1994 by the Purdue, Rutgers, and Illinois (PRI) apple breeding program. GoldRush was selected from a cross between Golden Delicious and Coop 17, says Jules Janick, professor of horticulture at Purdue University. GoldRush is named for its "old" gold color and rush of flavor, he explains.

For Mitch Lynd, a Johnstown, OH, grower, it was love at first bite. "I just never tasted anything with such flavor intensity," he exclaims. GoldRush's refractometer reading can hit 20% soluble solids, and never dips below 15%.

Ian Merwin, associate professor of pomology at Cornell University, caught GoldRush fever, too, and convinced Cornell's orchard manager to plant 150 trees, despite concerns that the variety would mature too late for the area. "Our first harvest was on second leaf, which is unusual on M.7, but is typical of GoldRush. We picked at Halloween. The apples didn't fully ripen in the field, but when we brought them out in February, they had developed a gold color, softened, and sweetened. Customers just raved about them," he says.

GoldRush is a good storage apple for sale in March or April when the quality of other apples is waning, says Janick. It's a low ethylene producer, notes Lynd, so it doesn't need CA storage.

Another welcome trait is its scab resistance. "You don't have to make a lot of fungicide sprays," says Janick.

One drawback however is its tendency to russet and subsequent cracking. Dick Unrath, Mountain Horticultural Crops Research and Extension Center, Fletcher, NC, says he's currently testing ProVide (gibberellic acid, Abbott Labs) for the russeting and speculates that it will help prevent cracking, too.

Taking The Direct Approach

Due to its tendency to russet and its smaller size, the variety is better suited for direct marketers. GoldRush commands a premium at Lynd's market. He charges $12 per half-bushel bag of GoldRush, Fuji, Gala, Suncrisp, and Honeycrisp. Other varieties go for $10 a bag. The crop from Lynd's 1200 GoldRush trees (all PYO) always sells out in three days.

GoldRush promises to be a good fit in North Carolina, too, where apple growers are shifting back to direct marketing, says Unrath. It will fill a gap between Rome and Pink Lady.

Planting And Thinning Tips

Before planting GoldRush, growers should determine the best rootstock and planting density for their orchard conditions. For example, don't put GoldRush on M.9 unless you do it on super high density, suggests Merwin. "We planted them on M.9 at 7 feet, but 5 or 6 feet would have been better. You could put them on M.111 at 8 feet and they would be all right," Lynd says.

To reduce sunburn, Unrath recommends free-standing, semi-dwarf trees, maybe M.26 or M.7A, for North Carolina orchards.

GoldRush isn't exceptionally vigorous, so it doesn't need a lot of pruning or training. "Its flat limbs spur up nicely and it has a natural vertical axis," says Merwin. The trees will overbear, however, so thinning is critical to prevent them from going biennial.

Merwin reports that GoldRush isn't easy to thin chemically in New York. In North Carolina, however, Unrath has had success using Sevin (carbaryl, Rhone-Poulenc) and a surfactant.

Stella Naegely is a contributing writer based in New Jersey.


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