2004 Annual Report
1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter?
California is the major producer of stone fruit and grapes valued at over $1,290 million. The fruit is shipped long distances to Eastern or export markets. Large volume and low fruit prices received at local markets and areas of production make stone fruits and grapes less profitable. Cultivars suitable for shipment with high quality fruit and a range of maturity to supply fruit in distant markets over a long period, meeting customer demand are needed. A breeding program to develop new cultivars that combine good eating quality, better shipping and storage ability, attractive appearance, and early to late ripening is being used to reduce shipping loss and increase consumption of stone fruit and grapes. In addition, seedless grapes that have naturally large berry size are being developed to reduce production cost and provide the seedless grapes that customers want. California produces the majority of raisins, valued at over $160 million. Major portions of the raisin crop have been lost to rain and rot during late picking due to shortage of labor and late ripening cultivars. Unavailability of labor, fall rains, and high disease pressure result in high production costs, poor quality fruit, and loss of production. Large amounts of chemicals are used to control disease on grapes, but this increases production costs and adds unwanted chemicals to the environment, and in some years the chemicals are ineffective. The development of germplasm and cultivars suitable for mechanical harvest with early ripening and resistance to powdery mildew and Pierce's disease will reduce these problems. Better selection methods to identify desirable individuals and genetic information about inheritance of resistance is urgently needed to make development of improved cultivars successful. Soil pests such as nematodes reduce the production of grapes and stone fruit causing whole orchards or vineyards to be removed. Soil fumigants are only partially effective, contaminate the environment, and are being phased out. The development of resistant rootstocks will afford great savings to the growers and reduce the use of pesticides. Almost 90% of the total US apricot acreage and tonnage are being produced in California. Fresh and processed apricot industries are valued at $50 million annually. These industries are based on only a few apricot cultivars that all ripen within a four week period of time. Therefore, harvested apricots must be packed, sorted, or processed within a very short timeframe. The development and evaluation of new apricot selections and cultivars suitable for cultivation in California growing regions will expand the harvest beyond the current four week period, producers would be able to expand the marketing period of fresh apricots. Newly developed industrial apricots for the important processing markets (drying, canning, freezing) that differ in ripening period from existing cultivars can assist in the operation efficiency of processing plants. Hybridizations between complementary apricot accessions are made to provide progenies that will extend the apricot season of fruit maturity both early and late.
The project has three specific objectives:.
1)to develop scion cultivars of stone fruit, nuts and grapes for fresh market and for dehydration with high quality and storage ability,.
2)to develop disease and pest resistant Prunus and Vitis scions and rootstocks,.
3)to develop genetic information to facilitate selection and enhance breeding efficiency.
The research to be undertaken falls under:
National Program 301 (70%) Plant, Microbial, and Insect Genetic Resources, Genomics and Genetic Improvement, addressing Component IIb - Genetic Improvement. More specifically the goals are: to increase shipping and storage life, fruit quality; combat losses due to pests, diseases, environmental stress; and increase production efficiency in Prunus and Vitis. Also, develop more rapid and efficient identification and incorporation of useful genes into crop germplasm.
National Program 303 (30%) Plant Diseases addressing Component V Host Plant Resistance to Disease. Specifically the goals are: to develop cultivars resistant to diseases, specifically powdery mildew, Pierce's disease, and nematodes.
New improved stone fruit and grape cultivars with high quality, shipping, storage and production efficiencies will sustain/profit American agriculture (many of them family farms), and supply high quality, nutritious fruits and nuts to US consumers and international markets. Raisin cultivars that dry naturally on the vine and can be mechanically harvested will revitalize the industry. Genetically-based control of pests and diseases that is effective and environmentally acceptable will contribute to the ongoing economics and productivity of stone fruit and grape production systems. Development of molecular markers and a better understanding of the genetic control of horticulturally important traits will allow early selection of progeny bearing desirable traits and improve breeding strategy for quantitative traits.
2.List the milestones (indicators of progress) from your Project Plan.
Year 1 (FY2004)
1.1 Hybridize apricots, evaluation of seedlings and advanced selections. Introduction of K713-98 apricot for the processing markets.
1.2 Field planting of new potential self-compatible almond hybrids from homozygous dominant sweet-kernel accessions.
1.3 Hybridize seedless grapes and recover plants by embryo rescue.
1.4 Hybridize seedless grapes and recover plants by embryo rescue. Collect data from advanced DOV trial and Zante Currant type DOV trial.
2.1 Harvest of seedlots from peach almond mother trees, preparation for planting trials. Write description of size controlling rootstocks.
2.2 Hybridize seedless table and raisin grapes with powdery mildew or Pierce's disease resistant germplasm. Recover plants by embryo rescue. Collect fruit data on populations for molecular marker studies.
2.3 Analyze grape seedling populations for phylloxera resistance segregation.
3.1 The scientist studying the Sf allele in Tuono was transferred out of the unit.
3.2 Scientist studying molecular markers for seedless trait in California grapes was transferred out of the unit.
3.3 Collect grapeleaf samples and extract DNA from one family segregating for phylloxera resistance.
3.4 Produce larger group of Friar X Helena progeny.
Year 2 (FY2005)
1.1 Propagate best stone fruit selections for advanced trials.
1.2 Completion of first round of bagging trials of almond seedlings segregating for self-compatibility and kernel bitterness.
1.3 Plant table grape seedlings in field.
1.4 Plant raisin grape seedlings in field.
2.1 Completion of bloom evaluations of male-sterile peach almond hybrid mother trees relative to Flordaguard, Nemared and Tsukuba No. 4. Release size controlling rootstocks to nurseries.
2.2 Screen seedlings in greenhouse for resistance. Plant seedlings in field and train. Test for correlation of markers with fruit traits and resistance.
2.3 Prepare manuscript on phylloxera resistance and submit for publication.
3.3 Screen grape population segregating for phylloxera resistance with molecular markers.
3.4 The scientist conducting the PCR analysis of Friar X Helena progeny was transferred out of the unit.
Year 3 (FY2006)
1.1 First evaluations of apricot populations for enhanced drying.
1.2 Identification of all bitter-kernel accessions in existing almond populations segregating for self-compatibility.
1.3 Train table grape seedlings in the field.
1.4 Train raisin grape seedlings in the field.
2.1 Rootstock seedling growth uniformity and vigor trials conducted.
2.2 Evaluate fruiting resistant grape seedlings. Propagate best for use as parents.
3.3 Evaluate candidate markers for phylloxera resistance.
Year 4 (FY2007)
1.1 Submit best advanced stone fruit selections for virus indexing.
1.2 Selection of self-compatible seedling with acceptable kernel qualities, propagation for field trials.
1.3 First fruit and evaluation of table grape seedlings.
1.4 First fruit and evaluation of raisin grape seedlings. Summarize data from DOV trials.
2.1 Advanced rootstock selections tested with commercial nursery for evaluation, graft compatibility studies.
2.2 Backcross selections to fruit quality. Recover plants by embryo rescue.
3.3 Analyze marker data for phylloxera resistance.
Year 5 (FY2008)
1.1 Prepare written descriptions of stone fruit selections for release.
1.2 Kernel sampling of advanced self-compatible selections for Almond Board of California evaluations.
1.3 Propagate and plant best table grape selections in 25 vine cultural trial.
1.4 Propagate and plant best raisin grape selections in advanced trial. Prepare manuscript on DOV trials and submit for publication.
2.1 Establishment of nursery trees for comparison of experimental rootstocks with commercial standards.
2.2 Screen grape seedlings in greenhouse for resistance. Plant seedlings in field and train.
3.3 Prepare manuscript on markers for phylloxera resistance.
A. List the milestones that were scheduled to be addressed in FY2004 (Year 1). How many milestones did you fully or substantially meet in FY2004 and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so.
The milestones listed below were scheduled to be completed under Year 1. All milestones were completed.
The breeding steps for the development of stone fruit and grape cultivars are a continuous process and are carried out each year. This includes making hybrids, recovering and growing plants, evaluating and selecting the best seedlings for parents to create the next generation of seedlings, and evaluating the best selections for potential as commercial cultivars.
1.1 The bloom season allowed for an ample supply of apricot seed from planned hybridizations. Apricot selection K713-98 was introduced for propagation and cultivation as an industrial apricot suitable for pulp, marmalades and canned halves.
1.2 Over 150 almond seedlings from planned hybridizations were planted to the field. These seedlings were hybrids between a self-compatible almond and parents homozygous for sweet kernel.
1.3 Over 1,300 table grape seedlings from 60 seedless x seedless crosses were planted in the field. This year 77 seedless x seedless crosses were made and 18,106 ovules cultured. Ten new promising seedless grape selections (4 red, 4 black and 2 white) were chosen from 208 table grape selections of which 63 were new. Over 783 samples from storage tests were evaluated. One late red, two late white and three early white seedless selections continue to show commercial promise. Patent application was submitted for a mid-season red seedless grape and it was released as Sweet Scarlet.
1.4 Over 1,300 raisin grape seedlings from 18 crosses were planted in the field. This year 23 seedless x seedless crosses were made and 5,253 ovules cultured. A total of 169 raisin selections, 139 that were new, were evaluated. Of these, 26 were propagated including seven dry-on-the-vine (DOV) selections. Twenty-three natural DOV selections fruited for the second time in the advanced DOV plot. Seven of the driest selections in 2002 had 95%+ of the fruit dry by August 25and were 99%+ dry by October 16, 2003 without cutting canes. Two Zante currant type selections with powdery mildew resistance, B36-44 and B37-48, fruited for the third time in a large planting and evaluated.
2.1 Seedlots from peach almond mother trees were harvested in preparation for planting trials. Descriptions of K146-43 and P30-135 size controlling rootstocks have been written and patents applied for jointly with University of California, Davis, CA.
2.2 Over 1,000 seedlings from 38 grape crosses with resistant to powdery mildew in greenhouse tests were planted in the field. Thirty-two seedless x seedless crosses were accomplished this year and 8,283 ovules cultured. Sixty-four new table grape and 61 raisin selections with powdery mildew resistance were kept. Dormant cuttings were taken of 147 table and raisin selections and tested for powdery mildew resistance in the greenhouse and 47 had an average leaf rating of less than 2.
Over 360 plants from crosses with Southeastern United States (SEUS) Pierce's disease resistant selections were planted in the field. Cuttings have been made from 176 seedlings to screen them in the greenhouse for resistance. This year 27 seedless x seedless crosses were made and 3,527 ovules were cultured to develop plants. These crosses consisted of BC2 populations from the Vitus rupestris x (V. arizonica x V. champinii) resistant germplasm, BC1 populations with SEUS resistant germplasm and a BC1 from V. rotundifolia resistant germplasm. Crosses were made for table, raisin and wine grapes. Of the 126 selections tested for PD resistance in the greenhouse, 37 were resistant. Populations screened in the greenhouse ranged from no resistance to 50% resistant offspring.
2.3 Data for resistant reaction to phylloxera has been analyzed.
3.2 The SCC8 primers to produce amplified products was tested in Thompson Seedless and test populations however the scientist studying molecular markers for seedless trait in California grapes was transferred out of the unit.
3.3 DNA samples have been extracted population segregating for phylloxera resistance.
3.4 Sixty seedling hybrids from the cross Friar (plum) X Helena (apricot) were planted to the field.
B. List the milestones that you expect to address over the next 3 years (FY2005, 2006 & 2007). What do you expect to accomplish, year by year, over the next 3 years under each milestone?
The Year 2, 3 and 4 milestones are listed below with a description of the anticipated outcomes.
Year 2 (FY2005)
1.1 Propagate best stone fruit selections for advanced trials. Seedling apricot accessions selected for high fruit quality compared to commercial standards will be propagated onto standard rootstocks for field evaluation. The propagated advanced selections will be evaluated against commercial standards ripening in the same time period.
1.2 Completion of first round of bagging trials of almond seedlings segregating for self-compatibility and kernel bitterness. - Trees within seedling almond populations will have branches bagged prior to bloom to exclude bee pollination and identify which of the trees are self-compatible. Seedling almond trees that produce fruit will be sampled for kernel bitterness. Bitter kernel almond seedlings will be removed from the population.
1.3 Hybridization of seedless grapes will continue with embryo rescue used to recover plants. Cultural trials of the advanced selections will continue to determine those suited for commercial production. Patent descriptions will be completed for two table grapes.
1.4 Hybridization of seedless raisin grapes that DOV naturally will continue with embryo rescue used to recover plants. A new planting for advanced DOV selections will be established. Testing to determine commercially acceptable natural DOV raisin genotypes will continue.
2.1 Completion of bloom evaluations of male-sterile peach almond hybrid mother trees relative to Flordaguard, Nemared and Tsukuba No. 4. Release size controlling rootstocks to nurseries. - Initial bloom and full bloom dates will be recorded for the male-sterile peach almond hybrids and compared with industry standards Flordaguard, Nemared and Tsukuba No. 4.
2.2 Hybridization of seedless table and raisin grapes with powdery mildew and PD resistant advanced selections will continue. Embryo rescue will be used to recover plants when necessary. Seedlings and selections will be tested in the greenhouse for resistance.
2.3 Manuscript for the segregation of resistance to phylloxera will be prepared and submitted for publication.
3.3 Screen grape population segregating for phylloxera resistance with molecular marker.
Year 3 (FY2006)
1.1 First evaluations of apricot populations for enhanced drying. Peach, plum and nectarine selections will continue to be evaluated for commercial potential and the best submitted for virus indexing. Collect fruit at harvest maturity and sulfur/sun-dry from apricot seedlings planted in 2003 specifically for drying quality. Dry-away will be noted, and color quality measured for each harvested selection. Samples will be stored to evaluate color retention.
1.2 Identification of all bitter-kernel accessions in existing almond populations segregating for self-compatibility. - From almond trees not sampled/selected in FY2005, remaining almond seedling trees will be evaluated for kernel bitterness.
1.3 Hybridization of seedless grapes will continue with embryo rescue used to recover plants. Cultural trials of the advanced selections will continue to determine those suited for commercial production. Early white selections will be evaluated for commercial potential in early growing district.
1.4 Hybridization of seedless raisin grapes that DOV naturally will continue with embryo rescue used to recover plants. Data from first natural DOV plot will be summarized and reported.
2.1 Rootstock seedling growth uniformity and vigor trials conducted. - Rootstock pits from selected peach almond mother trees will be tested with Nemaguard peach to examine nursery row uniformity and vigor.
2.2 Hybridization of seedless table and raisin grapes with powdery mildew and PD resistant advanced selections will continue. Selections from BC1 generations will be back crossed to quality again and selected for resistance.
3.3 Potential markers will be tested on individuals in the population to determine best for phylloxera resistance.
Year 4 (FY2007)
1.1 Submit best advanced apricot selections for virus indexing. - Apricot selections suitable for variety introduction will be submitted for virus indexing to NRSP-5 at Prosser, WA. If warranted, advanced peach, nectarine or plum selections will be released.
1.2 Selection of self-compatible seedlings with acceptable kernel qualities, propagation for field trials. - Almond seedlings that have proven to be both self-compatible, self-fruitful and having high kernel quality will be propagated for field trials under commercial conditions.
1.3 Hybridization of seedless grapes will continue with embryo rescue used to recover plants. Cultural trials of the advanced selections will continue to determine those suited for commercial production. Selections nearing introduction will be submitted for virus indexing to FPS, at Davis, CA.
1.4 Hybridization of seedless raisin grapes that DOV naturally will continue with embryo rescue used to recover plants. Data from second cycle of natural DOV raisin selections will be collected and evaluated.
2.1 Advanced selections tested with commercial nursery for evaluation, graft compatibility studies. - Collaboration planned with commercial nursery. Nursery will be provided with rootstock pits for nursery stock trialing. Important fruit and almond varietal standards will be grafted to various rootstocks. Nursery stock vigor and root characteristics will be compared to the same varieties grafted onto standard rootstocks.
2.2 Hybridization of seedless table and raisin grapes with powdery mildew and PD resistant advanced selections will continue. Advanced selections will be put propagated for field evaluation for resistance and fruit quality.
3.3 Data from candidate markers will be analyzed.
4.What were the most significant accomplishments this past year?
A. The California grape industry needs improved varieties of seedless
grapes to fill market gaps and provide novelty flavors to stay
competitive in a global marketplace. Scientists at
the Postharvest Quality and Genetics Research Unit, Parlier, California, developed, selected and evaluated hybrid populations of grape seedlings for the fresh market with seedless fruit and novel flavors.
The new Sweet Scarlet grape was introduced as a variety due to its
superior performance in variety trials, its strong and novel muscat
flavor and its mid season ripening date. Sweet Scarlet's introduction
should have a positive impact with consumers when it reaches the
supermarket produce section, as it will be the only grape currently
available that is both seedless and with the novel muscat flavor.
B. Commercial peach and nectarine trees are large and vigorous in growth
and need to be summer pruned to let light into the tree to color fruit
better and require ladders for most field operations. Scientists at the Postharvest Quality and Genetics Research Unit, Parlier, California, developed interspecific hybrid populations, performed initial selection of seedlings and made final evaluations cooperatively with scientists at the Department of Pomology, University, of California, Davis, California. Two plum X peach rootstocks conferring moderate vigor control to peach and nectarine scions were developed. As these new rootstocks are propagated and make their
way to peach and nectarine orchards, they should impact growers
favorably by reducing production costs related to the use of ladders and the need to summer prune.
C. Significant activities that support special target populations.
Support was provided to the Gila River Indian Reservation in Sacaton, AZ during FY04. Fifty Prunus rootstocks were provided to the reservation horticulturalist for testing new fruit varieties there. Apricot budwood was then shipped to the reservation for dormant grafting during February 2004. I anticipate long term collaboration with the horticulturalist there.
D. Progress Report opportunity to submit additional programmatic information to your Area Office and NPS (optional for all in-house('D') projects and the projects listed in Appendix A; mandatory for all other subordinate projects.
5.Describe the major accomplishments over the life of the project, including their predicted or actual impact.
1.1 Apache apricot introduction - Apricots of this newly introduced variety provide enhanced quality attributes compared to the presently available apricot during that season. Budwood has been distributed to all the major domestic commercial stone fruit nurseries for propagation, and it has further been distributed to interested growers as well. Apache apricot extends the marketing season of apricot by having mature fruit available approximately 5 days before the presently available earliest variety. Approximately 80 acres of Apache have been planted in the last year. Action Plan component NP301 IIb.
1.1 Galaxy was released to growers and nurserymen to provide a peento (flat or saucer-shaped) shape peach with better size, color, and sweetness than cultivars currently available. The variety will help enhance commercial peach production and availability of this shape peach to consumers. Over 50,000 trees have been produced by nurseries since its introduction. Action Plan component NP301 IIb.
1.2 Self-compatible almonds - Hybridizations of California-adapted almond accessions with the Spanish self-compatible 'Tuono' variety has led to new self-compatible almond accessions. Tuono differs greatly in kernel quality as compared to the almonds typical of California production. The new self-compatible hybrids are more like the California-adapted parent and two particular selections have been evaluated favorably for kernel quality. At present, these two self-compatible accessions are worthy of further field trials. Action Plan component NP301 IIb.
1.3 Seedless table grapes - Sweet Scarlet, a mid-season red seedless grape with a light muscat flavor was released to the grape industry and propagation rights assigned to the California Table Grape Commission. Muscat flavored grape production is limited to one seeded cultivar Italia and it has fallen from 164,690 boxes produced in 1997 to 88,049 boxes in 2000. It is likely that Sweet Scarlet production will fill this market. Action Plan component NP301 IIb.
1.3 A new seedless hybrid Thomcord was made available to growers and homeowners. The release will allow California growers to produce a seedless Concord flavored grape adapted to California. Action Plan component NP301 IIb.
2.1 Two plum x peach rootstocks, K146-43 and P30-135, which confer moderate vigor control to peach scions have been developed and patents applied for jointly with Department of Pomology, University of California, Davis, CA. Plant material is just being made available to nurseries and has the potential to reduce grower production costs. Action Plan component NP301 IIb.
6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
During FY04 Apache apricot was in demand by commercial nurseries. Over 10,000 buds of Apache apricot were provided to commercial stone fruit nurseries upon their request. Discussions with a large almond producer has led to a new trial involving nine ARS almond accessions. Five of these accessions resemble the important 'Nonpareil' variety, and the other 4 almond accessions are self-compatible. Successful trialing of these almonds under commercial orchard conditions is necessary prior to any variety release. In FY04 Prunus rootstocks and stone fruit dormant scionwood was provided to horticulturlists at an out-of-state Indian reservation. These fruit/vegetable specialists will determine the feasibility of growing stone fruits on reservation farms. Part of the 2004 crop of 'Nicole' apricot was harvested and provided to a commercial marmalade producer. 'Nicole' was introduced in FY03 as an industrial apricot well-suited to marmalade production. Budwood of 'Nicole' was later provided to the producer at his request.
Galaxy peach was again in demand in FY04 by commercial nurseries. Over 13,000 dormant cuttings and 10,000 June buds were supplied to commercial nurseries. Backyard growers continue to request propagation material of Galaxy. Information about the new ARS cultivars and the breeding program was provided to numerous U.S. and foreign growers and researchers. Fruit of recently released USDA varieties and advanced selections were shown at the monthly University of California 'Variety display and research update seminar' held in May and June.
Dormant cuttings of Thomcord grape were distributed to 43 individuals for propagation. At the same time requests were made of Princess and Summer Royal table grapes and Diamond Muscat and Summer Muscat raisin grapes.
Sweet Scarlet table grape was released and the propagation rights assigned to the California Table Grape Commission. They will sub-liscence nurseries for the propagation and sale of plants to growers.
7.List your most important publications in the popular press and presentations to organizations and articles written about your work.
1. Ramming, D.W. 2004. Notice to Fruit Growers and Nurserymen of the Release of Sweet Scarlet Grape. (Variety Release)
2. Apache Trees Take Root. American/Western Fruit Grower. p. 42 May 2004.
3. New apricot garners strong grower interest. The Grower. p. 18 May2004.
4. Breeders showcase new summer fruits. California Farmer. p. M1, 4, 5 July 2004.
5. Summer Fruits From ARS Research. Agricultural Research. p. 12-14 and Cover. April 2004.
6. Sweet and Seedless, A new seedless grape variety from USDA-ARS features a distinct flavor and color. Western Fruit Grower. p. 38. April 2004.
7. New peach has out-of-this-world shape, taste. The Grower. p. 33. June-July 2004.
8. New for your enjoyment' Summer Fruits From ARS Research. California Rare Fruit Growers, Inc. p. 8, 9, 25. July & August 2004.
9. Thomcord Grape? American Vineyard. p. 34. April 2004.
1. California Rare Fruit Growers, San Jose chapter. 10 April 2004. 'Breeding and evaluation of almonds, apricots and rootstocks for ARS.' Ledbetter, C.
2. California Commercial Nurserypersons Association, Annual Meeting. 22 June 2004. 'Update on apricot breeding efforts at the SJVASC in 2004.' Ledbetter, C.
3. Master Gardners, Fresno Chapter. June 22, 2004. Breeding new stone fruit and grapes. Ramming, D.W.
4. California Table Grape Commission grape research tour. July 29, 2004. Table grape breeding program. Ramming, D.W.
5. California Raisin Marketing Board field day. July 30, 2004. New cultivars and breeding for natural DOV and for mildew resistance. Ramming, D.W.
6. Schneider, S., Trout, T., Gerik, J., Ramming, D., and Ajwa, H. UC, Salinas. Methyl Bromide Alternatives for Perennial Field Nurseries' 1st and 2nd Year Performance. Presentation. 2003.
1. Badr, S. A., Ramming, D. W. and Tufenkjian, J. Response of Autumn Royal Table Grapevines to Different Levels of Pruning. Amer. J. Enology Viticulture Abstract poster. 2004.
2. Boyden, L. E., Cousins, P. and Ramming, D. W. Segregation of Resistance to Root-Knot Nematodes in a Vitis mustangensis Hybrid Population. Amer. J. Enology Viticulture Abstract poster. 2004.
3. Byrne, D. Vizzotto, M., Cisneros-Zevallos, L., Ramming, D., and Okie, D. 2004. Antioxidant content of peach and plum genotypes. poster #149 Session 27, Pomology. American Society Horticultural Science, Annual Meeting, Austin, TX.
Dejong, T.M., Ramming, D.W., Johnson, R., Doyle, J. 2004. Peach and nectarine rootstock named 'P30-135'. Patent Application. Serial Number 10/438,965.
Dejong, T.M., Ramming, D.W., Johnson, R., Doyle, J. 2004. Peach and nectarine rootstock named 'K146-43'. Patent Application. Serial No. 10/438,487.