Testing and Evaluation of and Plum Hybrid Cultivars Jerome L. Frecon and Daniel L. Ward Agricultural Experiment Station, Rutgers University

Introduction & Methods these cultivars are commonly called prunes. A botanical species, insititia or plum, is one of these This report is a continuation of plum, and cultivars. Varieties of the American, or wild, plum grow interspecific hybrids research first started by the on spreading trees and produce small, round fruit of senior author in 1989 and continued through 2011. various colors. These later two species have not been The Japanese type plum varieties adapted to the extensively evaluated in New Jersey and thus will not milder temperate climates of the Northeastern US be discussed in this report. are of great diversity. Many of these plum varieties are the result of interspecifi c hybridization. Most Varieties described as Japanese are the result of crosses of the Japanese plum, , with the The Japanese type varieties grown on available American plum, , or the rootstocks are generally short-lived and relatively plum or Simon plum, . More recently unproductive (there are exceptions). The trees are easily the Chickasaw plum, , has been stressed by many of the same problems affecting peach used by southern breeders to improve adaptability. trees, namely winter injury, spring frost, moisture stress, Generally, the Japanese type plum varieties grow on nematodes, root rots, and short life. Some Japanese upright spreading, or spreading to drooping trees and varieties also experience latent incompatibility with produce round to heart-shaped fruit (pronounced apex) available rootstocks and decline slowly. with yellow, to red, to almost black skin color. Plumcots Fruitfulness is also a problem in Japanese plums are interspecifi c hybrids of Japanese plums, Prunus because of bloom variability, pollen incompatibility, salicina, and , Prunus armeniaca. Plumcot and sensitivity to variation in temperatures and sunlight. is a generic term for these hybrids coined by Luther The Japanese varieties bloom earlier than other plum Burbank. ® are later-generations that show more species. Plumcots generally bear earlier than most plum than apricot characteristics; the fruit’s exterior has Japanese type plums. smooth skin closely resembling that of a plum. Pluots The following varieties have been suggested were developed by Floyd Zaiger and Zaiger Genetics, for small commercial plantings. The early season and “” is a registered trademark of Zaiger Genetics. varieties are: Early Golden, Methley, and Shiro. The Apriums® are complex plum-apricot hybrids that show midseason varieties are Crimson Beauty (USDA more apricot traits; genetically they are often one-fourth BY 8158-50), Au Rosa, Santa Rosa, Black Ruby, plum and three-fourths apricot. Aprium varieties were Red Ace, Redheart, Ozark Premier, Black Amber, developed in the late 1980s by Floyd Zaiger and Zaiger Wickson, Queen Rosa. The late season varieties Genetics, and “Aprium” is a registered trademark of are; Rubysweet, Vanier, South Dakota, Ruby Queen, Zaiger Genetics. NectaPlums are hybrids between and Fortune. plums and nectarines, Prunus persica. These also have There are many other Japanese and Japanese X been developed by Zaiger Genetics. The European, American hybrid varieties that have not been observed or common garden plum, varieties or tested in New Jersey. are more upright in growth habit and produce oval- to ovate-shaped plums with blue to black skin color. Some Pollination varieties have a dry texture, very high sugar content, and are processed into prunes. For this reason, many of All Japanese plums benefi t from cross-pollination.

12 Fruit Notes, Volume 77, Summer, 2012 Methley, Shiro and Early Golden will set heavy crops June 28-July 1. The skin has light pubescence. The fl esh in some years without cross-pollination. All other is medium fi rm, juicy, grainy and very sweet with very varieties should be planted in an orchard design with good fl avor. The trees are vigourous, spreading, and at least three varieties. have been productive particularly for a plumcot. Fruit Do not pollinate Japanese type plum varieties and size was respectable for an early season plumcot over the interspecifi c hybrids with European plum varieties. 2 inches in diameter. It is susceptible to bacterial spot.

Management USDA BY 96M514 – A yellow-fl eshed clingstone plum ripening on June 20. The average fruit weight was 78 The fi rst test block of Japanese type plums grams with 100% below 2 ¼ inches. Soluble solids was planted in a commercial orchard in Hardingville, concentration (SSC) was 9.6% in 2010. New Jersey. Four tree replicates of popular commercial varieties on Lovell and Halford peach rootstocks on an USDA BY 88Z1092 – A old peach orchard site. The block received normal care globose, small, 100% and attention similar to the care given adjoining peach dark bluish black, blocks. Fruit, fl ower and foliage characteristics were clingstone yellow-green- evaluated over the next fi ve years but tree decline and fleshed plum ripening death resulted in the trees being removed after six years. on June 27-July 6. The In 1987 the fi rst of a series of Japanese plum hybrids flesh is medium firm, were received from Dr. William “Dick” Okie. Research juicy, melting and sweet with good fl avor. The tree is Horticulturist and Fruit Breeder with the USDA – ARS spreading, vigorous, and lightly productive. Average Southeastern Fruit Research Station in Byron, Georgia. fruit weight was 26 grams and 9.6% SSC in 2010. Trees of these selections and other commercial varieties were planted over a 22 year period as two to four tree Honey Rich Aprium replicates in four research blocks interspersed with – This ovate, small, peaches and nectarines on commercial farms Most yellow-orange skinned blocks received normal care and attention throughout fruit with a prominent the season by the management of each farm. There are suture ripens from July currently 40 varieties under test in these blocks, some 1-7. The fl esh is yellow, that have duplicates. Other old varieties have been meaty, sweet and of removed. A few varieties were evaluated in test blocks excellent fl avor. The trees bloom very early and are at Adams County Nursery in Aspers, PA. of low vigor, upright spreading and lightly productive. The following are selections and cultivars that were SSC was 16.7 % in 2010, Very few fruit in 2011. or are currently under test or have been evaluated. This variety blooms very early so another very early blooming apricot is needed for pollination. It blooms PLUMS AND PLUOTS OF INTEREST so early it may have little use in New Jersey. (In Order of Ripening) Earliqueen plum – A globose, small to Tasty Rich Aprium – No fruit on these three year old medium small; 100% weak trees. All trees died in 2009. dark reddish purple, light yellow-fleshed Spring Satin – clingstone plum ripening A globose ovate, on July 2-8. The fl esh is medium, 90-100% medium fi rm, juicy with fair fl avor. The tree is vigorous, purplish red overcolor spreading and lightly productive and very susceptible with light yellow to to bacterial spot. After 15 years all of the trees were clear fl esh (some red removed. This variety has never been consistently pigmentation around productive, edges ripening from

Fruit Notes, Volume 77, Summer, 2012 13 USDA BY 8158-54 – A USDA BY96M1275 – globose to heart shaped, A globose to slightly medium small, 90-100% heart-shaped, 80-100% purplish red overcolor light speckled red over with a greenish red a yellow green ground groundcolor, red-fl eshed color; pinkish-yellow semi clingstone ripening fl eshed plum ripening on on July 2-6. The fl esh is medium fi rm, melting, stringy, July 10-16. The fl esh is medium fi rm, melting, juicy, sweet and acidic with fair to good fl avor. The tree is sweet with very good fl avor. The tree is vigorous, upright spreading, vigorous, moderately productive spreading, and lightly productive with medium with high susceptibility to leaf spotting. susceptibility to bacterial spot. SSC was 16.9% in 2010. The average fruit weight was 56 grams with 100% less USDA BY 8158-142 – A than 2 ¼ inches in diameter. globose, small 50 to 80% bright red over yellow Shiro - It is a globose to undercolor, clingstone heart shaped, medium- reddish yellow-fleshed sized (mostly 2 inches) plum ripening on July yellow skinned plum 2 to July 8. The flesh ripening July 12-19 is medium fi rm, juicy, melting and moderately sweet or 10 days after Early with fair to good fl avor. The tree is spreading. Vigorous Golden a similar but and lightly productive with moderate susceptibility to smaller fruited variety. bacterial spot. The average fruit weight was 32 grams The yellow semi- clingstone fl esh is soft but juicy with with 100% less than 2 ¼ inches. SSC was 12.6% in very good fl avor. It is partially self-incompatible and 2010. pollinated by, Methley, Vanier and Ruby Queen. Shiro is a good pollinizer for other early blooming plums. USDA BY 86M516 - A small, globose, 80- USDA BY 93M364 - 90% pinkish red with A globose, small, 90- a slight yellow green 100 % purplish red over ground-color yellowish, greenish yellow ground red-fl eshed, clingstone, color; yellow-fleshed plum ripening on July 2 -9. The fl esh is medium fi rm, clingstone plum ripening sweet, acidic with very good fl avor. The tree is very on July 14-20. The fl esh vigorous, spreading and has produced only light crops. is fi rm, melting, and acidic with good fl avor. The tree It has never exhibited much leaf spotting. Average fruit is vigorous, upright, and productive with medium weight was 27.1grams or 100% less than 2 ¼”. SSC susceptibility to bacterial leaf spot. SSC was 11.2% was 10.3% in 2010. in 2010. The average fruit weight was 39 grams with 100% of the fruit less than 2 ½ inches. USDA BY 91M97 – A small globose, 100 Methley – It is a globose purplish % reddish deep purple, red plum with red clingstone fl esh clingstone red-fleshed, ripening July 15-22. The fruit is plum ripening July 3- 10. small to medium size. The soft juicy The fl esh is medium fi rm, fl esh has fair to good fl avor, although sweet, acidic with very the skin has a slight aftertaste. It has good fl avor. The tree is large, vigorous and spreading the virtue of being self fertile and very productive and and lightly productive with medium susceptibility to will pollinate other early blooming varieties of Japanese bacterial spot. Average fruit weight was 42 grams with plums. Direct market growers will it because of 100% less that 2 ¼ inches. SSC was 14.7% in 2010. its long lived- tree and productivity.

14 Fruit Notes, Volume 77, Summer, 2012 USDA BY 8150-50 Black Ruby - A globose, – A globose, medium medium sized, 90-100% small 90% pinkish red reddish black fleshed, overcolor red- fleshed semi freestone plum semi-clingstone plum ripening on July 23-30. ripening on July 15- The fl esh is medium fi rm, 22. The flesh is firm, melting, stringy, sweet melting, sweet tart with good fl avor. The tree is with good fl avor. The tree is vigorous, spreading, vigorous, spreading, and moderately productive, with lightly productive and susceptible to bacterial leaf medium susceptibility to bacterial leaf spot. SSC was spot. Productivity improves in NJ with pollination 10.7% in 2010. The average fruit weigh is 89 grams by Ruby Queen, Methyl, Shiro and Vanier. For many with 83 % less than 2 ¼ inch and 7 % 2 ¼ inch. years we have been calling a smaller, earlier maturing, red-fl eshed clingstone variety Black Ruby. We are USDA BY 8327-65 - A confi dent this variety description and picture fi ts the globose to heart shaped, true Black Ruby. small, 100% dark reddish purple, red-fl eshed semi USDA BY 88M878 – clingstone plum ripening A globose, small, 100% on July 18-24. The fl esh purplish red, red-fl eshed, is medium fi rm, stringy, clingstone, ripening from sweet mild, with very good flavor. The tree is July 25 -31. The fl esh is spreading, vigorous, and moderately productive with medium firm, melting, low susceptibility to bacterial spot. The average fruit juicy, sweet acidic, with weight is 59 grams with 100% less than 2 ½ inches SSC very good fl avor. The tree is spreading, vigorous, was 15.9% in 2010. and lightly productive with medium susceptibility to bacterial spot. The average fruit size was 42 grams Bubblegum Plum(R) Plum with 98 % below 2 ¼ inches and 2% at 2 ¼ inches. SSC Prunus salicina hybrid was 14.1% in 2010. ‘Toka’ cv. It is a small bronze red globose plum ripening on Ozark Premier –It is a July 20-26. The fl esh is soft, globose, large, red skinned clingstone and yellow with a plum ripening from good but gummy texture. The tree is upright, vigorous, August 1- 7. The yellow lightly productive, and self incompatible and needs clingstone fl esh has good a pollinizer of one of the other American x Japanese fl avor. The tree is vigorous hybrids. Bubblegum is a registered trademark of Paul but crops irregularly. It Friday, Coloma . This cultivar blooms early, is self incompatible and fl owers heavily but has not set much fruit. needs cross pollination. Vanier is an excellent pollinizer for Ozark Premier. USDA BY 8334-16- A oval to ovate very Fortune - Large, globose, small, 100% purplish reddish purple blush over red overcolor, greenish- yellow ground color, yellow fl eshed clingstone yellow-fl eshed clingstone, plum ripening on July ripening on August 6-12. 22-25. The fl esh is fi rm, The flesh is firm, juicy melting, and sweet, with good fl avor. The tree is very and sweet with very good vigorous, spreading, and lightly productive, with high fl avor. The tree is upright-spreading, vigorous and susceptibility to bacterial leaf spot. All trees died in productive. It is pollinated by other Japanese type 2009. varieties.

Fruit Notes, Volume 77, Summer, 2012 15 Coparose Pluot productive with low susceptibility to bacterial spot. -Evaluated from Adams It is self-incompatible and pollinated by Shiro, Ruby County Nursery. A Queen, Ozark Premier and Santa Rosa. The average globose to slightly fruit weight was 45 grams and 100% of the fruit is less ovate, medium to large, than 2 ¼ inches. SSC was 14.3% in 2010. bluish red skinned, pluot ripening August USDA BY 93M597 – A 8-16. The fl esh is a fi rm golden fl esh, semi freestone, small, globose to heart and a fl avor that is very good. The vigorous tree requires shaped, 100% reddish a pollinizer such as Dapple Dandy according to Dave purple, greenish yellow- Wilson Nursery. It has been moderately vigorous and fl eshed clingstone plum lightly productive. We have limited experience with ripening on August 12- pollinizers in the eastern US. 18. The flesh is firm, juicy, and acidic with good fl avor. The tree is very Flavor Grenade Pluot vigorous, upright, medium productive, and susceptible – A globose to slightly to leaf spot. The average fruit weight was 56 grams ovate, medium sized with 100% less than 2 ¼ inches in diameter. SSC was yellowish green ground 14.7% in 2010. color overlaid with a speckled reddish orange, Castleton(European greenish yellow flesh, type plum) – An ovate semi freestone pluot ripening August 10 -18. The fl esh to oval small to medium is fi rm, fi ne grained, sweet, low acid with excellent small, 100% bluish fl avor. The trees are vigorous, lightly productive and black, yellowish green- susceptible to leaf spotting. The fruit weight was .83 fl eshed, freestone plum grams with 50% less than 2 ¼ inches and 50% 2 ¼ to ripening on August 10- 2 ½ inches. SSC was 17.1% in 2010. 18. The fl esh is medium firm stringy, dry with USDA BY 88M1010 good fl avor. The trees are is moderately vigorous, – A medium, globose, upright, very productive, and tolerant of bacterial spot. yellow, firm-fleshed, The average fruit weight is 43 grams with 100 % less clingstone plum ripening than 2 21/4 inches. SSC was 17.3% in 2010. Like many on August 9 -15. The blue black European plums it sometimes gets picked skin is a greenish red. too early. The fl avor is very good. The tree is vigorous, upright and moderately productive. SpiceZee NectaPlum. The average fruit weight was 69 grams with 100% of Evaluated from Adams the fruit less than 2 ¼ inches in diameter. SSC was County Nursery It is a 13.2% % in 2010. 2¼ to 2½ inch globose, light bronze, pinkish, Vanier - A small to medium red skinned nectaplum globose, bluish-red, yellow- ripening from August 15 orange-fleshed clingstone, to 22. The fi rm freestone cream colored fl esh. It has ripening in August 15 -23. The a slightly acidic and spicy sweet fl avor. Dave Wilson fl esh is moderately fi rm, juicy says it is a beautiful ornamental tree with a tremendous with good flavor. The fruit spring bloom followed by dark red leaf in the spring hangs on the tree well. The that matures to a rich green-red in late summer. This tree is upright-spreading, vigorous, and moderately variety is self-fruitful and very productive.

16 Fruit Notes, Volume 77, Summer, 2012 Ruby Queen - Large, juicy, melting sweet and low acid with excellent globose, dark reddish- fl avor. The tree is moderately vigorous, upright, lightly purple, red-fl eshed, semi productive and very susceptible to leaf spotting and shot freestone plum ripening holing. The average fruit weight was 83 grams with in August 17-23. The 90 % less than 2 ¼ inches and 10 % over 2 ¼ inches. fruit hangs and ripens SSC was 17.7% in 2010. over a long period of time. The fl esh is fi rm, and juicy with excellent fl avor. New York 6 –A small, The tree is medium, spreading, vigorous, and productive oval to ovate, blue with moderate susceptibility to bacterial spot. It is greenish, yellow-fl eshed pollinated with another Japanese type variety like Shiro, freestone plum ripening Vanier, and Black Ruby. Tested as USDA BY8155-70. on August 22 -30. The SSC was 18.5% in 2010. tree is upright spreading vigorous, spreading, productive, and tolerant to leaf Flavor Queen – A spotting. Trees were removed in 2011. globose, medium to large, yellowish green, Crimson Royale Pluot. semi-freestone light Evaluated from Adams yellow-fleshed plum County Nursery. It is ripening from August an ovate to globose, red 21 -30. The fl esh is fi rm, skin over a dull yellow juicy, melting, sweet and undercolor pluot ripening low acid with excellent August 24 to September fl avor. The tree is vigorous, low productivity with high 1. It has a cream yellow, susceptibility to leaf spotting. The average fruit weight very fi rm, semi-freestone was 146 grams with 14% 2 ¼ inches, 15% 2 ½ inches fl esh with excellent quality and fl avor. The trees are and 40% 2 ¾ inches. SSC was 18.3% in 2010. 2010 vigorous, spreading, and lightly productive. It requires was fi rst year out of 12 year that this variety has had a a pollinizer but must be studied further in the Eastern full crop. In 2011 the crop was very light. .

USDA BY 8356-33 – A small, globose, 80- Arial – A small, globose, 90% yellowish red yellowish brown russeted overcolor over a slight plum with yellow green greenish yellow ground flesh ripening in late color yellow-fleshed August. The trees were clingstone plum ripening very weak and all trees on August 25-30. The fl esh is medium fi rm, melting, died in the spring of 2010. sweet, acidic with very good flavor. The tree is The trees never produced enough quality fruit to get a vigorous, spreading, moderately productive, and good evaluation. susceptible to leaf spotting. Dapple Dandy Pluot Flavor King Pluot – A – A globose, medium, medium globose to heart red-freckled skin over shaped small 80-90% yellow green undercolor; purplish red; reddish semi-freestone pink to yellow clingstone pluot red fl esh pluot ripening ripening on August 22- August 24 to September 2 30. The flesh is firm The fl esh is medium fi rm,

Fruit Notes, Volume 77, Summer, 2012 17 juicy, acidic and sweet with excellent fl avor. The trees Candy Stripe Pluot – are small, moderately vigorous, spreading, with high Evaluated from Adams susceptibility to bacterial spot. The average fruit size County Nursery. It was 109 grams with 36% less than 2 ¼ inches and 64 is a globose medium % over 2 1/inches. SSC was 17.5 % in 2010. large sized, pinkish red overcolor with a yellow Autumn Sprite Aprium undercolor ripening – Evaluated from Adams September 1-10. The fl esh is yellow, freestone, fi rm, County Nursery. It is and juicy with a very good acidic fl avor. Dave Wilson a globose to ovate Nursery says it requires a pollinizer such as Flavorfall. yellowish-pink skinned The young trees had a light crop so more work needs ripening from August 25 to be studied on pollinizers in the Eastern US. to September 2. The fl esh is yellow and freestone with very good sweet fl avor. Autumn Giant – A The fruit is medium size, about 2 inches. The tree is globose to heart shaped, vigorous and spreading. Dave Wilson Nursery states small to medium 80-90% that it is self fertile. If this leads to high productivity bright orange red over a in the Eastern US this could be a promising variety orange-yellow ground as young trees had a good crop. color; yellow-fleshed clingstone ripening in Flavor Rich Pluot – late September. The A generally globose, fl esh is melting, very fi rm, stringy, mild and acidic with small to medium fair fl avor. The tree is upright and slightly spreading, sized, 100% purplish moderately productive. This plum ripens so late it is black greenish yellow- hard to get a reading on good quality. fl eshed, clingstone pluot ripening on August 25 to Rootstocks September 2. The fl esh has fair fl avor but stays so fi rm it is hard to determine maturity. The tree is vigorous, Myrobalan( ) seedlings and spreading and of all the pluots is the most productive. Myrobalan 29C clonal stocks are the recommended The average fruit size is 79 grams with 70 % less than rootstocks for all European plum varieties. They are 2 ¼ inches and 30% over 2 ¼ inches. SSC was 13.6% also compatible with many Japanese and Japanese X in 2010. Trees were removed in 2011. American hybrid varieties, but tend to be shorter-lived on sandy or drought sensitive soils. They are more Flavor Heart Pluot. adapted and longer-lived on loamy or clay-loam soils. Evaluated from Adams Lovell and Halford peach seedlings are used on County Nursery. It is a many Japanese plum varieties. Trees are short-lived globose to heart shaped, and susceptible to most problems experienced with large sized, bluish black peach varieties. Japanese plum varieties on Lovell and pluot ripening from Halford peach seedlings are better adapted to sandy August 22 to September soils than European varieties on Lovell or Halford. 1. The semi freestone Mariana 2624 clonal rootstock is compatible with light yellow fl esh is fi rm most plum varieties. Trees of all varieties are more but softens quickly. It has excellent fl avor. Flavor Heart sensitive to low winter temperatures on this rootstock requires a cross pollination according to Dave Wilson than other rootstocks. Nursery. The tree was small with a light crop. Citation appears to be a promising rootstock for

18 Fruit Notes, Volume 77, Summer, 2012 semi-dwarf plum trees. semi dwarf tree. Krymsk 1. A New rootstock from Russia has not Pumiselect is a dwarfi ng clonal selection of Prunus been tested in New Jersey but is being offered with pumila sold with Japanese type plum. Japanese plums as very winter hardy and producing a

Editors' Note: These plums were evaluated in southern New Jersey, and there, the ripening date is about the same as for comparable trees at Adams County Nursery in Aspers, PA. Northern New Jersey ripening dates range from 5 to 10 days later, depending on locaƟ on.

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