ORCHARD EDITION


Tree Fruits Galore

Flavor, texture and easier growing
By Dorothy Noble




Sweet cherry breeder Dr. Nnadozie Oraguzie inspects a tree for pollination. Washington State should soon release his latest cherry, which is larger and firmer and has better flavor than his Chelan sweet cherry, but has similar harvest timing.
Photo courtesy of Dr. Nnadozie Oraguzie.

Today, tree fruit breeders have more tools than ever before. Innovations in genetic sequencing as well as other advances in breeding technologies have facilitated new developments in various crops.

The RosBREED project, funded by the USDA's National Institute of Food and Agriculture, exemplifies the advances obtainable. The Rosaceae crops research effort includes apples, apricots, peaches, pears, plums, sweet cherries and tart cherries. Project director Dr. Amy Iezzoni, Michigan State's (MSU) tart cherry breeder, says of the program accomplishments, "It's really exciting and has the potential to increase new variety breeding. Of course, that's the endgame - better taste, grower-friendly and faster breeding."

Specifically, the project's work in applying marker-assisted breeding delivers improved plant materials more efficiently. The RosBREED data, combined with traditional breeding plus biotechnology, promises to improve fruit quality and help combat disease and insect pests much more quickly. In the past, tree fruit variety development typically took more than a decade.

Data on the following new tree fruit cultivars were available by press time. More information, such as patent or royalty status and growth characteristics, can typically be obtained from the university or developer websites.

Apples

RubyFrost stores particularly well, rewarding consumers with vitamin C well into winter. It ripens later than another New York release, SnapDragon. Dr. Susan Brown developed both cultivars at Cornell University in partnership with New York Apple Growers (NYAG). RubyFrost, tested as NY2, offers crisp juiciness as well as a pleasantly balanced sugar-acid taste. Its uses are comparable to Empire and Granny Smith, but frosty-looking ruby-red skin distinguishes RubyFrost. The managed release by Cornell/NYAG includes exclusive licensing in North America.

Tested as NY1, SnapDragon's juicy crispness derives from one of its parents, Honeycrisp. Consumers especially savored its texture and spicy-sweet flavor. One New York grower suggests it for children's snacks. Ripening in late September, it also has a long shelf life and stores well. Cornell and NYAG also have a licensing agreement for SnapDragon. Both cultivars have some disease and insect resistance.

Washington State University's (WSU) first release, WA 2, has drawn acclaim for its outstanding eating quality. Dr. Katherine Evans heads the breeding program. Combined with its appearance and productivity, WA 2 has the characteristics to be an exceptional cultivar. The orange-red to pinkish-red blush covers 70 to 90 percent of its yellow background. Plus, its conspicuous lenticels set it apart from other varieties and enhance its visual appeal. The round fruit is medium to large, very firm, crisp and juicy. It can be enjoyed for the fresh market in late September or stored medium to long-term for later sales. Called Crimson Delight by one grower, others can choose a different name.



Developed at the New York State Agricultural Experiment Station by Cornell University breeder Dr. Susan Brown, RubyFrost is destined for popularity. The breeding process for this winner began in 1992. This fall, customers at selected farmstands devoured it.
Photo by Dr. Susan Brown.

Developed at WSU by crossing Enterprise and Honeycrisp, WA 38 will suit the fresh market from its late September harvest through long-term storage. Plus, its very low enzymatic browning trait should boost its desirability for fresh-cut and fruit salad purposes. Sensory evaluations indicate top-notch eating quality. Harder than Fuji and Gala, but softer than Braeburn and Cripps Pink, its juiciness exceeds all four varieties. Compared to Honeycrisp, it has similar crispness and juiciness, yet is harder. Its round to conical large fruit sports a reddish-purple blush over a greenish-yellow background. Little russeting, sunburn or bitter pit has appeared in trials. The WSU Research Foundation manages the licensing and commercialization of WA 38.

The project's apple breeders note that Honeycrisp, developed with Dr. James Luby's program at the University of Minnesota, has set the standard for the crispness now demanded by consumers.

Nectarines

Amoore Sweet brings a unique low- acid, mango-like flavor to fresh-market nectarines. Developed by Dr. John Clark's University of Arkansas breeding program, it averages 15.2 percent soluble solids, with firm, non-melting flesh. Similar to Bradley in size, this yellow-orange clingstone nectarine's red blush enhances its attractiveness. Early to midseason, it stores well. In addition, it yields well and resists bacterial spot.

Early to midseason Bowden has firm, non-melting white flesh that averages 13.8 percent soluble solids. Bowden is high-yielding, with good storage potential and bacterial spot resistance. Medium-large, it produces in early July, averaging three days after Bradley. This Arkansas clingstone nectarine's red blush over three-fourths of its cream color bolsters its fresh-market appeal. Nectarine standard acidity enlivens Bowden's sweet flavor.

Low acid, sweetness and exceptional quality characterize Texas A&M's Smooth Delight nectarine series. Dr. David Byrne notes that these mark the first subacid nectarines for the southeastern U.S. medium chill zone. Smooth Delight One has white flesh, while Smooth Delight Two's flesh is yellow. Both Smooth Delights have high productivity and, depending on thinning, reward growers with medium to large fruit. Neither show a tendency to brown, form split pits or crack. Ripening occurs in mid-May after Flordaking peaches, but before TexKing peaches. The Smooth Delights need 400 to 450 chill units.

Fresh-market peaches

With protection in Texas' medium chill zone, TexFirst ripens in late April. Its yellow flesh has excellent firmness and size considering its early ripening. Appearance, soluble solids and flavor drew higher ratings than Flordaking or TexKing in both Texas and California trials. The flesh of this Texas A&M peach does not show a tendency to brown readily or develop split or shattered pits during the final stage of fruit swelling. The vigorous tree has a semi-spreading growth habit.

From the University of Arkansas breeding program, the yellow, slow-melting freestone Souvenirs peach matures around Independence Day. This early midseason, low-acid peach with red-blushed skin has exceptional flavor, with soluble solids averaging 15.3 percent. It stores well and moderately resists bacterial spot. The Souvenirs variety weighs an average of 183 grams.

Texas A&M's White Delight fresh-market peach series was propagated by a few Texas and Tennessee nurseries this year. These new peach cultivars - bred to provide firm, attractive, subacid, white-fleshed fruit - ripen from late May until early June in Texas' medium chill zone. White Delight One and Two require 550 chilling hours, while Three and Four require about 700 chilling hours. All are medium to large, depending on the number of fruit left on the tree.

The Zest peach series, also released by Texas A&M, has cropped consistently in the region where TexRoyal, JuneGold and Harvester grow. With traditional acidity, the top-quality Zest cultivars can supply firm yellow peaches from mid-May until late July in regions similar to Texas' medium chill zone. The late-blooming releases - Royal Zest One, Royal Zest Four and Golden Zest - need 600 chilling hours. Royal Zest Three requires 550 hours, and Royal Zest Two needs about 500 chilling hours to break dormancy. The Zest peaches are medium to large, depending on thinning practice.

Processing peaches

The University of California, Davis (UC Davis), has released three yellow-gold, non-melting clingstone processing peaches. Medium-large Goodwin matures one week before Elberta, has good storability and harvests easily. Its chill requirements are greater than 800 hours. Also medium-large, Lilleland matures two weeks prior to Elberta. It also has good ease of harvest and storability, plus moderate resistance to Monilinia fruit rot. Lilleland's chill requirements are more than 700 hours. Extra Early#1 produces large fruit two weeks after Elberta. It also requires 700 chill hours. It ranks very good for both harvest ease and storability traits, and it will hold on the tree for two weeks. UC Davis' Dr. Thomas Gradziel says all three of the processing peaches taste sweet, with enough acid to enhance their flavor.



Whether just picked or plucked from storage, Gem will beautify a produce display, and its delectable flavor will satisfy the most discerning chef.
Photo courtesy of USDA.

Pear

Gem, a USDA-developed pear, bears in early September. Dr. Richard Bell, USDA research horticulturist, reports that this productive cultivar has had good consumer acceptance when sampled either crisp or softened. Fruit size is moderate, but can be improved by thinning and by delaying the harvest where fruit reaches 250 grams. Harvesting over a three-week period does not affect storability. Even five-month storage shows little loss of quality or firmness, and Gem moderately resists fire blight. A joint release by Oregon State, MSU and Clemson University, Gem excels in both fruit quality and appearance. It has been tested in every pear-growing region in the U.S.

Arctic apples

Okanagan Specialty Fruits (OSF) expects Arctic Golden and Arctic Granny to be fully deregulated in 2014 and commercially available in 2015. OSF used genetic engineering to counteract natural apple browning. The company inserts a synthetic gene derived from apples to suppress the enzyme polyphenol oxidase, which causes browning when the fruit is bruised or cut. According to OSF, the gene sequence used has been recognized as harmless to humans, and the two varieties have undergone rigorous testing for 10 years. Neal Carter, OSF president, adds that Arctic apples provide convenience and reduce food waste. The USDA's Animal and Plant Health Inspection Service scheduled the final deregulation public comment period to end December 16, 2013. The initial comments were more in opposition than in support.



The only tart cherry breeder in North America, Dr. Amy Iezzoni of Michigan State University introduced Hungary's multipurpose tart cherry Balaton to the U.S.
Photo by Derrick L. Turner/Michigan State University.

Since genetically engineered foods continue to be controversial, OSF suggests that consumers visit its website (http://www.arcticapples.com). The company is developing genetically engineered versions of Gala and Fuji. The U.S. Apple Association (USApple) says that it supports innovation in the industry. While recognizing that consumer concerns have been vocalized, USApple says consumers can choose among a wide array of apples.

Cherries

New dwarfing rootstocks have facilitated high-density sweet cherry orchards by instigating earlier initial and peak production. These more intensive orchards also improve fruit quality, production efficiency and harvesting ease. An MSU team is studying these systems for tart cherries, and Iezzoni is developing new rootstocks. MSU is also investigating different harvesting systems to speed the time for first harvest. The goal is harvesting from 2 or 3-year-old trees (usually it takes five to seven years). Young tart cherry trees cannot withstand being shaken during harvest. But some machines now used for harvesting other crops, such as blueberries, citrus and grapes, look promising for high-density cherry orchards.

The WSU breeding program of Dr. Nnadozie Oraguzie aims for sweet cherries with high consumer appeal. In selecting superior genotypes, he focuses on fruit quality, then selects traits including productivity, postharvest attributes and disease resistance. Current leading cultivars are targeted for larger fruit size, mechanical harvest ability and powdery mildew resistance.

Citrus

Several relatively new citrus releases from the USDA's Agricultural Research Service (ARS) are low-seeded variants of older cultivars. The breeding of citrus is challenging and different from other familiar tree fruits. Early-season maturity, moderately sized fruit, deep orange pebbled rind, rich sweetness and considerable seeds characterize Fallglo tangerine. US Early Pride, a Fallglo mutation, is nearly seedless and easily peeled - traits in a mandarin that delight consumers. The propagated trees are moderately vigorous, thornless, upright and slightly spreading with dense foliage. The fruit matures in mid-October.

Both US Furr, a hybrid of Clementine and Murcott, and its mutant, US Furr-ST, show considerable promise in numerous citrus-producing areas. When evaluated, tasters report these mandarins as among the best-tasting citrus ever. In addition, US Furr-ST tolerates citrus scab. Both mature in December/January. The oblate-shaped fruit's smooth to slightly pebbly rinds peel fairly easily. Color is excellent.

US Seedless Pineapple is a low-seeded variant of the old standby Ridge Pineapple sweet orange. The fruit of US Seedless Pineapple, except for fewer seeds, is comparable to the orange Pineapple on various rootstocks. Also, larger marketable yields should result because fruit drop has been less prevalent in trials.

Drs. Ed Stover and Greg McCollum of the ARS aim to create new combinations of citrus, select superior traits, and create new scions to resist bacterial canker and, most importantly, resist or tolerate huanglongbing (HLB or citrus greening). HLB threatens to devastate U.S. citrus production and is now widespread in Florida.

HLB diminishes fruit quality. Once infected, trees decline over several years, resulting in reduced production and death. At its current rate of spread, researchers predict that virtually all Florida citrus plantings will be affected in less than a decade.

It is critical to control HLB's vector (Asian citrus psyllid) and develop HLB-resistant or tolerant cultivars. Florida funding and testing are accelerating.

Although not yet certain for long-term production, some cultivars are less susceptible to HLB than sweet oranges and grapefruit. US Early Pride and Fallglo are among them.

Sweet oranges are virtually genetically identical, being mutations of some ancient hybrid. At present, Florida researchers do not believe that an HLB-resistant sweet orange will be found. However, over a century of effort by the USDA citrus breeding program has produced several hybrids very similar to sweet oranges that appear to offer greater HLB tolerance. These, of course, require broad testing.

Stover observes, "Transgenics are likely the best chance for immunity to huanglongbing." He notes that genetic engineering also permits improvement in cultivars otherwise essentially identical to established types.

The author is a writer-researcher specializing in agriculture. She currently resides in central Pennsylvania.