Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to NRP
GENETICS AND VARIETAL IMPROVEMENT OF STRAWBERRIES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
Reporting Frequency
Annual
Accession No.
0131438
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2011
Project End Date
Nov 7, 2014
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Plant Sciences
Non Technical Summary
California strawberry growers face the combined challenge of competitive markets, increasing labor cost, and growing regulatory obstacles to use of their most effective cultural tools. The purpose of this project is to provide genetic solutions to the problems faced by commercial strawberry growers, by development and release of strawberry cultivars with improved production and harvest efficiency, better fruit quality, and broad tolerance to environmental stresses.
Animal Health Component
60%
Research Effort Categories
Basic
20%
Applied
60%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2011122108070%
2031122108015%
2051122108015%
Goals / Objectives
Develop and utilize strawberry germplasm in an applied program aimed at breeding, testing and selection of new cultivars adapted to arid-subtropical and Mediterranean climates, with improvement targets that include production characters, harvest efficiency, fruit quality, and environmental tolerance
Project Methods
The above objectives will be met by genetic evaluation of relevant phenotypic variables in cross-fertilized populations and tested predominantly in commercial field environments, by development and utilization of appropriate selection and breeding lines, and by development and application of appropriate scoring and screening procedures. The relevance of these experiments will ultimately be verified by determination of the commercial potential of cultivars in commercially relevant production environments.

Progress 10/01/11 to 11/07/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Retired as of November 7,2014. Is Unavailable

Publications


    Progress 01/01/13 to 09/30/13

    Outputs
    Target Audience: Strawberry growers and genetics research specialists in arid subtropical regions Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Our project has hosted 3 region-wide field days and its members have made multiple formal and informal presentations to strawberry industry and grower clients. How have the results been disseminated to communities of interest? Information has been transferred through direct contacts, presentations and field days (see above), and research bulletins posted on the project web site. What do you plan to do during the next reporting period to accomplish the goals? Cultivar release will remain the project priority, using established procedures. Dissemination of information will continue through direct contacts, field days, presentations and web reports.

    Impacts
    What was accomplished under these goals? Our project completed disclosure and commercial release for one high quality short-day strawberry cultivar and has initiated the disclosure process for 3 additional short-day strawberry selections. Three day-neutral selections have been advanced to pre-release stage in 2013. These day-neutral selections are under continued commercial evaluation and a release decision is expected by early 2015. We continued our testing program in 2013 to include an evaluation of the genetic resistance to Fusarium oxysporum infection and and initiated a procedure for genetic development of resistance to this pathogen. We also perfected and tested a simple infection system for evaluating genetic resistance to Macrophomina phasiolina.

    Publications

    • Type: Websites Status: Published Year Published: 2013 Citation: Douglas V. Shaw and Kirk D. Larson. 2013. Qualitative performance comparisons of short-day selection C229 (7.132-3) with Ventana and Benicia. UC Strawberry Bulletin 2013-1, 2p. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet_pdf/UCStrawberry_Bulletin2013-1b.pdf
    • Type: Websites Status: Published Year Published: 2013 Citation: Douglas V. Shaw and Kirk D. Larson. 2013. Performance of short-day selection C229 (7.132-3) at the South Coast REC and Watsonville Strawberry Research Facility in 2010-2012. UC Strawberry Bulletin 2013-2, 2p. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet_pdf/UCStrawberryBulletin2013_2.pdf
    • Type: Websites Status: Published Year Published: 2013 Citation: Kirk D. Larson and Douglas V. Shaw. 2013. Qualitative performance comparisons of short-day selection C231 (8.20-602) with Ventana and Benicia. UC Strawberry Bulletin 2013-3, 2p. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet_pdf/UCStrawberry_bull_2013-3.pdf
    • Type: Websites Status: Published Year Published: 2013 Citation: Douglas V. Shaw and Kirk D. Larson. 2013. Qualitative performance comparisons of short-day selection C232 (8.55-2) with Ventana and Benicia. UC Strawberry Bulletin 2013-4, 2p. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet_pdf/UCStrawberry_bull_2013-4.pdf
    • Type: Websites Status: Published Year Published: 2013 Citation: Kirk D. Larson and Douglas V. Shaw. 2013. Qualitative performance comparisons of short-day selection C235 (8.132-608) with Ventana and Benicia. UC Strawberry Bulletin 2013-5, 2p. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet_pdf/UCStrawberry_bull_2013-5.pdf


    Progress 01/01/12 to 12/31/12

    Outputs
    OUTPUTS: Our project has advanced 6 short-day strawberry selections and 3 day-neutral selections to pre-release stage in 2012. These selections are under continued commercial evaluation and a release decision is expected by early 2014. Substantial effort has been expended on soil disease issues for strawberry. We expanded our testing program in 2012 to include an evaluation of the consequences of Fusarium oxysporum infection and genetic resistance on commercial productivity and completed a seedling evaluation of the inheritance of resistance to this pathogen. We also developed and tested a simple infection system for evaluating genetic resistance to Macrophomina phasiolina. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    As the result of programmatic modifications initiated in 2007, progress in developing short-day cultivars has accelerated, and we anticipate widespread utility of the more advance selections especially regarding fruit quality attributes. The day-neutral selections under consideration for release generally reflect incremental improvements to cultivars of this type presently used in California and elsewhere, all of which originated from our breeding program.

    Publications

    • Larson, K. D. and D. V. Shaw 2012. Annual Pomology Project Report 2011-2012. http://www.plantsciences.ucdavis.edu/ucstrawberry/index.html. 7pp.


    Progress 01/01/11 to 12/31/11

    Outputs
    OUTPUTS: Our project released two new short-day cultivars, Benicia (C225) and Mojave (C227) in 2010, and these were evaluated in their first commercial year in 2011. We continued to develop cultural methods in support of these cultivars in Southern California and around the world. Substantial effort has been expended on soil disease issues for strawberry. We expanded our testing program in 2011 to include two diseases, Fusarium oxysporum and Macrophomina phasiolina, that have entered the California production environment due to widespread use of the substandard soil fumigants mandated by the regulatory elimination of methyl bromide. We initiated inheritance studies for resistance to both of these pathogens. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

    Impacts
    One of the short-day cultivars released in 2010, Benicia, is obtaining widespread adoption in California and based on preliminary performance is expected to be the dominant cultivar in Spain starting in 2014. The commercial evaluation to date verifies markedly improved fruit quality attributes, especially flavor, for this cultivar. Fruit quality presently limits the competitiveness of growers dependent on short-day cultivars in California.

    Publications

    • Larson, K. D. and D. V. Shaw 2011. California Strawberry Commission 2010-11 Annual Pomology Project Report. http://www.plantsciences.ucdavis.edu/ucstrawberry/index.html.


    Progress 01/01/10 to 12/31/10

    Outputs
    OUTPUTS: Our project released two new short-day cultivars, Benicia (C225) and Mojave (C227), which have proven broadly adapted to production systems in Southern California and similar production environments throughout the world. Also, we continued to develop cultural methods in support of the cultivar 'San Andreas' in Southern California. Preliminary results continue to support the utility of this day-neutral cultivar in environments traditionally filled only by short-day cultivars. Use of San Andreas in non-traditional production systems is increasing in Spain and Mexico as a consequence. Substantial effort has been expended on soil disease issues for strawberry. We continued our analysis of the inheritance resistance to Verticillium dahliae Kleb., demonstrating long-term selection response sufficient to meet modern industry needs. Also, we provided a summary evaluation of Methyl Iodide as a soil fumigant. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    The two short-day cultivars released last year represent the next incremental step in international strawberry cultivar development. These releases combine the production pattern and production capacity of existing cultivars with markedly improved fruit quality attributes, especially flavor. Despite the movement of the day-neutral cultivar 'San Andreas' into typical short-day systems, the majority of the strawberry industry worldwide desires standard cultivar types; short-day cultivars offer cost advantages in nursery production which make them economically competitive, and remain somewhat easier to grow than the day neutral cultivars. These short-day cultivars represent substantial improvements in fruit quality, flavor, and appearance, over other standard cultivars available in California and worldwide. Fruit quality presently limits the competitiveness of growers dependent on short-day cultivars.

    Publications

    • Shaw, D. V., T. R. Gordon, K. D. Larson, W. D. Gubler, J. Hansen, and S. C. Kirkpatrick. 2009. Genetic progress in breeding for resistance of strawberry to Verticillium Wilt. California Agriculture 64: 37-41.
    • Shaw, D. V. and K. D. Larson. 2010. `Benicia' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Shaw, D. V. and K. D. Larson. 2010. `Mojave' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Larson, K. D. and D. V. Shaw 2010. California Strawberry Commission 2009-10 Annual Pomology Project Report. http://www.plantsciences.ucdavis.edu/ucstrawberry/index.html.
    • Shaw, D. V. and K. D. Larson. 2010. Performance of Short-day Cultivars Benicia and Mojave at the Watsonville Strawberry Research Facility in 2008 - 2010 UC Strawberry Bulletin 2010-1.
    • Shaw, D. V. and K. D. Larson. 2010. Performance of Three Short-day Advance Selections Compared with Short-day Cultivars at the Watsonville Strawberry Research Facility in 2009 - 2010. UC Strawberry Bulletin 2010-3.
    • Shaw, D. V. and K. D. Larson. 2010. Evaluation of Five Fumigation Alternatives at the Watsonville Strawberry Research Facility in 2008 - 2009 UC Strawberry Bulletin 2010-2.


    Progress 01/01/09 to 12/31/09

    Outputs
    OUTPUTS: Our project continued to develop cultural methods in support of 3 new day-neutral cultivars released in 2008: San Andreas, Monterey, and Portola. These cultivars have replaced a substantial fraction of the Albion cultivar in central California during fall of 2009, and their low chill requirement together with exceptional fruit quality has increased their acreage to over 2,000 acres in Southern California. Preliminary results have suggested similar adoption potential in Spain and Mexico. Registration was initiated for two new short-day cultivars, Benicia (C225) and Mojave (C227), which have proven broadly adaptable in Southern California. We continued our analysis of the inheritance resistance to Verticillium dahliae Kleb., separating resistance and tolerance mechanisms that affect field resistance. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    The three day-neutral cultivars released last year represent the next large step in international strawberry cultivar development. The present releases combine the positive features of Albion, the most commonly grown day-neutral cultivar in the world, with productivity that is improved by 30 percent or more and low-chilling requirements. San Andreas confers substantial cost savings by reduced need for runner pruning. These factors combined within day-neutral cultivars may revolutionize strawberry production systems throughout the world by introducing such genetic mechanisms into regions previously dependent on short-day flowering types only. The short-day cultivars released represent substantial improvements in fruit quality, flavor, and appearance, over their predecessor Ventana. Short-day cultivars offer cost advantages in nursery production which make them economically competitive, and remain some what easier to grow than the day neutral cultivars.

    Publications

    • Shaw, D.V., Gordon, T.R., Hansen, J., and Kirkpatrick, S.C. 2009. The relationship between the severity of individual plant infection by Verticillium dahliae Kleb. and symptom expression in relatively resistant genotypes of strawberry (Fragaria x ananassa Duch.) Plant Pathology. In press.
    • Scott, J.C., Shaw, D.V., and Gordon, T.R. 2009. Effect of temperature and inoculum density on Fusarium wilt of lettuce, caused by Fusarium oxysporum f. sp. lactucae. Plant Disease. In press.
    • Larson, K.D. and Shaw, D.V. 2009. California Strawberry Commission 2008-09 Annual Pomology Project Report. http://www.plantsciences.ucdavis.edu/ucstrawberry/index.html.
    • Shaw, D.V. and Larson, K.D. 2009. Monthly productivity of four day-neutral strawberry cultivars at the U.C. Davis Watsonville Strawberry Research Facility in 2005 to 2008. UC Strawberry Bulletin 2009-1. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet.html.
    • Shaw, D.V., Larson, K.D., Gee, Daren, and Coehlo, Joe. 2009. Performance of short-day selections C225 (4.39-1) and C227 (4.44-603) at the South Coast REC, Santa Maria, and Watsonville Strawberry Research Facility in 2008 and 2009. UC Strawberry Bulletin 2009-2. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet.html.
    • Shaw, D.V. and Larson, K.D. 2009. Qualitative performance comparisons of short-day selections C225 (4.39-1) and C227 (4.44-603) with Ventana. UC Strawberry Bulletin 2009-3. http://www.plantsciences.ucdavis.edu/ucstrawberry/sheet.html.


    Progress 01/01/08 to 12/31/08

    Outputs
    OUTPUTS: Our project released 3 new day-neutral cultivars San Andreas, Monterey, and Portola. These cultivars have intended adaptation for central California, but their low chill requirement together with exceptional fruit quality indicates potential for use in non-traditional locations such as southern California, Spain, Florida, and Mexico. The Portola cultivar is somewhat stronger in flowering response than most UC cultivars and fits a commercial system that should make it widely planted in both southern California and northern Europe. Plant material was substantial at release, and we estimate over 2,500 acres combined for the three cultivars in their first year, which is unprecedented. We continued our analysis of the inheritance resistance to Verticillium dahliae Kleb., demonstrating progress over the 14 year selection effort originated in 1994. More fundamental research on V. dahliae was successful in separating resistance and tolerance mechanisms that affect field resistance. Long term evaluations of genetic progress also demonstrated the stability of the genetic progress for productivity traits obtained for strawberry by the UC program over widely divergent horticultural systems. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

    Impacts
    The three day-neutral cultivars released this year represent the next large step in international strawberry cultivar development. Our program released the cultivar Albion in 2004, and this became the most widely planted cultivar in California is just 3 years due to its flavor and disease resistance. The present releases combine the positive features of Albion with productivity that is improved by 30 percent or more. Furthermore, development by the UC strawberry breeding program of low-chill day-neutral cultivars with exceptional fruit quality may revolutionize strawberry production systems throughout the world by introducing such genetic mechanisms into regions previously dependent on short-day flowering types only.

    Publications

    • Shaw, D. V. and Larson, K. D. 2007. Strawberry genetics, breeding, physiology and production management. Annual report to the California Strawberry Commission.
    • Shaw, D. V., Larson, K. D., and Gee, D. 2007. Performance of short-day cultivar Palomar at the South Coast REC, Santa Maria, and Watsonville Strawberry Research Facility in 2004-2006. California Strawberry Commission Strawberry Research Report, May 22, 2007.
    • Shaw, D. V. and Larson, K. D. 2008. Monterey strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Shaw, D. V. and Larson, K. D. 2008. San Andreas strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Shaw, D. V. and Larson, K. D. 2008. Portola strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Shaw, D. V. and Larson, K. D. 2008. Performance of early-generation and modern strawberry cultivars from the University of California breeding programme in growing systems simulating traditional and modern horticulture. J. Hort. Sci. and Biotech. 83:648-652.
    • Shaw, D. V. and Larson, K. D. 2008. Strawberry genetics, breeding, physiology and production management. Annual report to the California Strawberry Commission.
    • Shaw, D. V. and Larson, K. D. 2008. The UC Davis strawberry breeding program releases three new day-neutral cultivars. California Strawberry Commission Strawberry Research Report, March 25, 2008.
    • Shaw, D. V., Gordon, T. R., Larson, K. D., Gubler, W. D., Hansen, J., and Kirkpatrick, S. C. 2009. Progress in breeding for resistance of strawberry (Fragaria Hananassa Duch.) to Verticillium dahliae Kleb. due to 14 years of parent selection. California Agriculture, submitted.
    • Shaw, D. V. and Larson, K. D. 2007. Peformance of summer-planted day-neutral selection CN224 and Albion at the University of California South Coast REC, Irvine in 2005 and 2006 Web report.
    • Shaw, D. V. and Larson, K. D. 2007. Performance of short-day cultivar Palomar at the South Coast R.E.C. (Irvine), Santa Maria, and Watsonville Strawberry Research Facility in 2004-2006


    Progress 01/01/07 to 12/31/07

    Outputs
    Our project released a new short-day cultivar named Palomar, with intended adaptation for southern California, Spain, Florida, and Mexico. Plant material is limited in this initial year, but preliminary commercial feedback from the earliest locations, Florida specifically, suggest this cultivar will be the dominant type in some markets. We also completed experimental activity in preparation for release of 3 new day-neutral cultivars which are currently in the disclosure process. These selections have a range of flowering responses, uniformly high production, and exceptional fruit quality that will make them useful in systems worldwide. We continued our analysis of the polygenic inheritance of long-day flowering (day-neutrality) in strawberry by developing populations that breed true for the major locus that confers long-day flowering and selecting for variable flowering strength. This work is in progress but preliminary analyses indicate selection response, thus verifying the presence of polygenic variation. Evaluation of methods for Phytophthora cactorum resistance screening was completed with segregating seedling populations; this work demonstrated significant additive variation for the genes that condition Phytophthora cactorum resistance.

    Impacts
    The value to California growers of a short-day cultivar replacement is substantial, especially given that the attributes of the Palomar cultivar include improved fruit quality and harvest efficiency over existing alternatives. Development by the UC strawberry breeding program of low-chill day-neutral cultivars with exceptional fruit quality may revolutionize strawberry production systems throughout the world by introducing such genetic mechanisms into regions previously dependent on short-day flowering.

    Publications

    • Shaw, D. V. and K. D. Larson. 2007. Palomar strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Shaw, D. V., J. Hansen, G. T. Browne, and S. M. Shaw. 2007. Components of genetic variation for resistance of strawberry to Phytophthora cactorum estimated using segregating seedling populations and their parent genotypes. Plant Pathology. In press.
    • Luby, J. J., and D, V. Shaw. 2007. Plant Breeders Perspectives on Improving Yield and Quality Traits in Horticultural Food Crops. HortScience. In press.
    • Larson. K. D., and D, V. Shaw. 2008. Producing strawberry fruit for off-season market windows in California. NASS. Accepted.
    • A. R. Inman, S. C. Kirkpatrick and T. R. Gordon, and D. V. Shaw. 2007. The effect of temperature on growth and spore germination in Gibberella circinata, the cause of pitch canker. In press.
    • Ajwa, H., S. Klose, M. Bolda, and D. V. Shaw. 2007. Effect of Methyl Bromide Alternative Fumigants on Fertility in Strawberries. Annual report to the California Strawberry Commission.


    Progress 01/01/06 to 12/31/06

    Outputs
    Our project continued to evaluate cultural practices and make horticultural recommendations for the day-neutral strawberry cultivar 'Albion', released in 2004. Grower confidence in this cultivar is strong, and it will be harvested from about 9,000 Acres in 2007, well above the initial market expected. After completing analysis of the polygenic inheritance of long-day flowering (day-neutrality) in strawberry using last year, we initiated studies of alternative mechanisms of flowering control, detecting a possible correspondence between these secondary systems and genetic processes that confers early fruiting. Multi-year evaluations of variation in the virulence of different V. dahliae isolates were completed; some variation in virulence was detected but an absence of interactions suggests that the resistance developed using combined isolate mixes will provide stable response to this disease. A six-year evaluation of methods for Phytophthora cactorum resistance screening was completed and interactions due to test year and inoculum source judged to be of minimal consequence to obtaining selection response. Further research with segregating seedling populations demonstrated significant additive variation for the genes that condition Phytophthora cactorum resistance. Release of a short-day cultivar with superior fruit quality characteristics is planned for spring of 2007.

    Impacts
    'Albion' fruit will be harvested from approximately 25 percent of the planted area in California in 2007 and may provide 35 percent of the state's fruit. The added value to California growers of this cultivar replacement is difficult to predict, but the quality traits of this item have speeded its rate of adoption and generated name recognition not experienced in the history of the UC breeding program. Most growers expect the quality features of this cultivar to stimulate strawberry consumption. Research results from studies of V. dahliae and P. Cactorum will simplify genetic testing for resistance to these diseases and create opportunities for understanding polygenic resistance mechanisms.

    Publications

    • Shaw, Douglas V., John Hansen and Greg T. Browne. 2006. Genotypic Variation for Resistance to Phytophthora cactorum in a California Strawberry Breeding Population. J. Amer. Soc. Hort. Sci. 131:687-690.
    • Gordon, Thomas R., Douglas V. Shaw, and Kirk D. Larson. 2004. Characterization of genetic mechanisms of resistance to Verticillium in California strawberries. California Strawberry Commission Annual Production Research Report: 2003-04: 104-113.
    • Shaw, Douglas V. and Kirk D. Larson. 2004. Strawberry genetics, breeding, physiology and production management. California Strawberry Commission Annual Production Research Report: 2003-04: 136-144.
    • Shaw, Douglas V. and Kirk D. Larson. 2005. Strawberry genetics, breeding, physiology and production management. California Strawberry Commission Annual Production Research Report: 2004-05: 169-182.
    • Shaw, Douglas V. and Kirk D. Larson. 2006. Strawberry genetics, breeding, physiology and production management. California Strawberry Commission Annual Production Research Report: 2005-06:
    • Gordon, T. R., S. K. Kirkpatrick, J. Hansen, and D. V. Shaw. 2006. The response of strawberry genotypes to inoculation with isolates of Verticillium dahliae differing in host origin. Phytopathology (In press)
    • Shaw, Douglas V. and Kirk D. Larson. 2006. Performance of three day-neutral strawberry selections at the Watsonville Strawberry Research Facility in 2004 and 2005. The Pink Sheet: California Strawberry Commission strawberry news bulletin, March, 2006.
    • Shaw, Douglas V. and Kirk D. Larson. 2006. Performance of short-day selection C221 (00.259-2) in Irvine, Santa Maria, and the Watsonville Strawberry Research Facility in 2004 and 2005. The Pink Sheet: California Strawberry Commission strawberry news bulletin, March, 2006.
    • Zalom, F. G., Shaw, D. V., and K. D. Larson. 2006. Strawberry Insects In California, Ecology and Control. In: Encyclopedia of Pest Management.


    Progress 01/01/05 to 12/31/05

    Outputs
    Progress report: Our project continued to develop and disseminate cultural practices recommendations for the day-neutral strawberry cultivar 'Albion', released in 2004. Grower experience in the first commercial year has determines this cultivar to be superior in all respects to the 'Diamante' cultivar, which until this year has been planted on 28% of California's acreage and produced approximately 35-40% of the state's fruit annually. We completed analysis of the polygenic inheritance of long-day flowering (day-neutrality) in strawberry using Complex Segregation Analysis, which indicated the presence of a major locus that determines 75% of the variation for this characteristic. This finding creates the possibility of developing advanced strawberry breeding populations that are true-breeding for day-neutrality, but variable for the strength of this trait. Infection experiments with for strawberry with V. dahliae indicated that the resistance developed to date by the UC breeding program is stable to inoculum propagule type (conidia and micro-sclerotia). Likewise, variation was detected in the virulence of different V. dahliae isolates, but the resistance developed to date was stable over all isolates tested. A three-year study of the consequences of commercial nursery infection in susceptible and resistant strawberry genotypes was completed, and demonstrated that the most important resistance mechanism in this population acts by restricting the transfer if infection through vegetative propagules rather than exclusion of the pathogen by the root system. My research also completed a multi-year study on the inheritance of seedling characteristics for dried plums and their response to inbreeding.

    Impacts
    Impact: 'Albion' fruit was harvested commercially from about 300 acres in 2005, fall plantings that will produce fruit for 2006 are estimated at 2,800 acres, or 40% of the target market; this acreage was limited by plant availability. Nursery estimates for the following year predict that the demand for this cultivar will be approximately 6,000 acres. The added value to California growers of this cultivar replacement is difficult to predict, but the rate of adoption we are experiencing is more rapid than any in the history of the UC breeding program. Demonstration of a major locus affecting the polygenic inheritance of day-neutrality opens the possibility of developing true-breeding populations for this trait could offer a substantial gains in efficiency for future strawberry cultivar development activities. Research results from studies of V. dahliae isolates will simplify genetic testing for this trait and create opportunities for understanding polygenic resistance mechanisms. The genetic information generated for dried plums is presently utilized by the UC breeding program under the direction of Professor Theodore DeJong.

    Publications

    • Shaw, Douglas V., Thomas R. Famula. 2005. Complex Segregation Analysis of Day-neutrality in Domestic Strawberry (Fragaria x ananassa Duch.). Euphytica 145: 333-340.
    • DeBuse, Carolyn J., Douglas V. Shaw, and Theodore M. DeJong. 2005. Response to Inbreeding of Seedling Traits in a Prunus domestica Breeding Population. J. Amer. Soc. Hort. Sci. 130: 904-911.
    • Shaw, Douglas V., Thomas R. Gordon, Kirk D. Larson, and Sharon C. Kirkpatrick. 2005. The Effect of Verticillium Infection in Runner Plant Propagation Nurseries on Resistant and Susceptible Strawberry Genotypes. J. Amer. Soc. Hort. Sci. 130:707-710.
    • Shaw, Douglas V. and Kirk D. Larson. 2005. Performance of Diamante and Albion at the Watsonville Strawberry Research Facility in 2004 with Fruit Harvested Weekly and Bi-weekly. The Pink Sheet: California Strawberry Commission strawberry news bulletin, January, 2005.
    • Shaw, Douglas V. and Kirk D. Larson. 2005. Cultivar update: Performance of Albion at the Watsonville Strawberry Research Facility in 2004 With and Without Preplant application of Aliette. The Pink Sheet: California Strawberry Commission strawberry news bulletin, January, 2005.
    • Shaw, Douglas V. and Kirk D. Larson. 2005. Performance of Short-day Selection 00.259-2 at the South Coast REC, Santa Maria, and Watsonville Strawberry Research Facility in 2004. The Pink Sheet: California Strawberry Commission strawberry news bulletin, February, 2005
    • Shaw, Douglas V. and Kirk D. Larson. 2005. Performance of Four Advanced Strawberry Selections at the Watsonville Strawberry Research Facility in 2004 With Runner Plants From Original and Meristemmed stock. The Pink Sheet: California Strawberry Commission strawberry news bulletin, February, 2005.
    • Shaw, Douglas V. and Kirk D. Larson. 2005. Annual Research Report to the California Strawberry Commission. May, 2005.
    • Debuse, Carloyn, Douglas V. Shaw, and Theodore DeJong. 2004. Heritabilities for SeedlingTtraits in a Prunus domestica Breeding Population. Acta Horticulture.
    • Zalom, F. G., T. Glick, D. Limburg, and D. Shaw. 2004. Twospotted Spidermite Control, 2001. Arthropod Management Tests 29: C21.
    • Gordon, Thomas R., Douglas V. Shaw and Kirk D. Larson. 2005. Comparative response of strawberries to conidial root dip inoculations and infection by soilborne microsclerotia of Verticillium dahliae Kleb. HortScience 40:1398-1400.


    Progress 01/01/04 to 12/31/04

    Outputs
    Our project released the day-neutral strawberry cultivar 'Albion', formerly identified as CN220, to the California nursery industry for propagation and sale within California. This cultivar has superior performance for productivity, fruit quality, harvest efficiency, and environmental tolerance to the 'Diamante' cultivar, which currently is planted on 28% of California's acreage and produces approximately 35-40% of the state's fruit annually. This cultivar has especially high resistance to Phytophthora cactorum and Verticillium dahliae, two faults of the 'Diamante' cultivar. Continued analysis of the polygenic inheritance of long-day flowering (day-neutrality) in strawberry using Complex Segregation Analysis indicated the presence of a major locus that determines 75% of the variation for this characteristic. This finding creates the possibility of developing advanced strawberry breeding populations that are true-breeding for day-neutrality, but variable for the strength of this trait. Infection experiments with for strawberry with V. dahliae indicated that the resistance developed to date by the UC breeding program is stable to inoculum propagule type (conidia and micro-sclerotia). Likewise, variation was detected in the virulence of different V. dahliae isolates, but the resistance developed to date was stable over all isolates tested. A three-year study of the consequences of commercial nursery infection in susceptible and resistant strawberry genotypes was completed, and demonstrated that the most important resistance mechanism in this population acts by restricting the transfer if infection through vegetative propagules rather than exclusion of the pathogen by the root system.

    Impacts
    Based on information available to date, 'Albion' will likely replace 'Diamante'. The added value to California growers of this cultivar replacement is difficult to predict, but could be near the approximately $140,000,000 per year generated by 'Diamante' when it replaced its predecessor. Demonstration of a major locus affecting the polygenic inheritance of day-neutrality resolves a perennial genetic question. Furthermore, the possibility of developing true-breeding populations for this trait could offer a substantial gains in efficiency for future strawberry cultivar development activities. Together, the research results from studies of V. dahliae suggest the opportunity for developing stable horizontal resistance to this disease, and indicate both the methods and resources that will be required to do so.

    Publications

    • Shaw, D. V. and K. D. Larson. 2004. 'Albion' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Shaw, D. V. and K. D. Larson. 2004. Genetic variation and response to selection for early season fruit production in California strawberry seedling (Fragaria x ananassa Duch.) populations. J. Amer. Soc. Hort Sci. (In Press).
    • Shaw, D. V. and K. D. Larson. 2003. Cultivar update: Qualitative performance summary for winter-planted CN220. The Pink Sheet: California Strawberry Commission strawberry news bulletin 03-011, December 10, 2003.
    • Shaw, D. V. and K. D. Larson. 2003. Cultivar update: Performance of CN220 at the Watsonville research facility with differing planting date and tarp date. The Pink Sheet: California Strawberry Commission strawberry news bulletin 03-012, December 10, 2003.


    Progress 01/01/03 to 12/31/03

    Outputs
    Nursery inoculation trials detected genotypes expressing variation for two potential sources of resistance to Verticillium dahliae (initial resistance to infection and tolerance to disease pressure despite substantial disease load) in a range of resistant types; crosses among these genotypes will permit genetic resolution of these mechanisms. Nursery treatments and genetic resistance for Colletotrichum acutatum, were extended to broader samples of genotypes. A long-term genetic study of the northern California UC breeding population demonstrated genetic gains of 20-78% over a 10 year period for traits of commercial importance, with no discernible concomitant decrease in genetic variation. Evaluation of genetic variation for early-season fruit production in the southern California UC breeding population demonstrated continued opportunity for developing early-fruiting cultivars, but suggest that parent selection will be substantially more effective in this effort than individual seedling evaluations. A series of studies conducted over 7 years was completed that conclusively demonstrate the polygenic inheritance of long-day flowering in strawberry. One day-neutral selection with superior performance for productivity, fruit quality, harvest efficiency, and environmental tolerance was evaluated in final grower trials and scheduled for release.

    Impacts
    The long-term genetic study demonstrates ongoing opportunity for genetic improvement of strawberry in California, despite substantial past genetic change and the absence of germplasm infusions; these results suggest alternative mechanisms for generation of the variation responsible for continued selection response. Demonstration of polygenic inheritance of day-neutrality resolves a perennial genetic question and dictates appropriate future breeding strategy for utilization of this characteristic. Based on UC and grower trials, the day-neutral selection scheduled for release will likely replace a cultivar that produces about 40% of the fruit annually shipped from California and should become the most widely planted day-neutral cultivar in the world.

    Publications

    • Gordon, T.R., Kirkpatrick, S.C., Shaw, D.V., and Larson, K.D. 2002. Differential infection of mother and runner plant generations by verticillium dahliae in a high elevation strawberry (Fragaria x ananassa Duch.) nursery. HortScience 37:927-931.
    • Shaw, D.V., Gordon, T.R., and Larson, K.D. 2002. Runner plant cold storage reduces verticillium dahliae kleb. Infection of nursery origin in strawberry (Fragaria x ananassa Duch.). HortScience 37:932-935.
    • Shaw, D.V. and Gordon, T.R. 2003. Genetic reaction for resistance to verticillium wilt (Verticillium dahliae Kleb.) in strawberry (Fragaria x ananassa Duch.)with two-stage family and genotypic selection. HortScience 38(3):432-434.
    • Shaw, D.V. 2003. Heterogeneity of segregation ratios from selfed progenies demonstrate polygenic inheritance for day-neutrality in strawberry (Fragaria x ananassa Duch.). J. Amer. Soc. Hort. Sci. 128(4):504-507.
    • Shaw, D.V., Zalom, F.G., and Larson, K.D. 2003. Relative differences in yield for strawberry (Fragaria x ananassa Duch.) genotypes are stable over differing levels of infestation by twospotted spidermites (Tetranychus urticae Koch.). J. Amer. Soc. Hort. Sci. 128(5):678-681.
    • Shaw, Douglas V. and Larson, Kirk D. 2003. Consequences of nursery, pre-plant, and field fungicide treatments for percent dry calyx and productivity in Camino Real at the Watsonville Strawberry Research Facility in 2002. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 03-02, February 21, 2003.
    • Shaw, Douglas V. and Larson, Kirk D. 2003. Advanced selection update: Performance of four day-neutral selections at the Watsonville Strawberry Research Facility 1999-2002. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 03-03, February 21, 2003.
    • Zalom, Frank, Thompson, Pat, Limburg, David, and Shaw, Doug. 2003. Strawberry miticide evaluations, 2002. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 03-04, March 31, 2003.


    Progress 01/01/02 to 12/31/02

    Outputs
    Horticultural treatments recommended for two short-day strawberry cultivars released to the California industry in 2001 (Ventana and Camino Real) were refined and summarized for grower use. The Ventana cultivar was evaluated across a range of potential cultural environments, including tunnel production, a system appropriate to European production and of increasing popularity in California. The cultivar Camino Real was evaluated specifically for adaptation to earlier plantation establishment and early season fruit quality. Dry calyx on early Camino Real fruit was demonstrated to be a physiological rather than a pathogen-induced trait. Nursery trials detected genetic variation for two potential sources of resistance to Verticilliumdahliae: initial resistance to infection and tolerance to disease pressure despite substantial disease load. Nursery treatments and genetic resistance were evaluated for Colletotrichum acutatum, a disease with infrequent but potentially severe effects on plat establishment in California. Cultural methods for preventing disease in nursery stock and for treating infected nursery stock prior to fruiting field establishment were evaluated. Efforts to develop genetic resistance to Phytophthora cactorum, Verticillium dahliae and Tetranychus urticae were continued. Four day-neutral selections with superior performance for productivity, fruit quality, harvest efficiency, and environmental tolerance were advanced to pre-release grower trials.

    Impacts
    The two cultivars released in 2001 were planted on approximately 10% of California production acreage and are expected to comprise 50% in a two-year period. Demonstration of a physiological basis for dry calyx in Camino Real may reduce pesticide consumption. The results for Verticillium resistance research demonstrating multiple mechanisms of resistance should lead to the development of stable resistance to this pathogen.

    Publications

    • Walsh, D. B., F. G. Zalom, D. V. Shaw, and K. D. Larson. 2002. Yield Reduction Caused by Twospotted Spidermite (Acri:Tetranychidae) Feeding in an Advanced Cycle Strawberry Breeding Population. J. Amer. Soc. Hort. Sci. 127:230-237.
    • Shaw, D. V., and T. R. Gordon. 2002. Genetic Reaction for Resistance to Verticillium Wilt (Verticillium dahliae Kleb.) in Strawberry (Fragaria xananassa Duch.)with Two-stage Family and Genotypic Selection. HortScience (In press).
    • Shaw, Douglas V. and Kirk D. Larson. 2002. Cultivar update: Performance of Ventana at the Watsonville Strawberry Research Facility with differing nursery harvest date, and planting date. The Pink Sheet: California Strawberry Commission strawberry news bulletin 02-03, January 31, 2002.
    • Shaw, Douglas V. and Kirk D. Larson. 2002. Cultivar update: Performance of Camino Real at the Watsonville Strawberry Research Facility with differing nursery location, nursery harvest date, and planting date. The Pink Sheet: California Strawberry Commission strawberry news bulletin 02-04, February 4, 2002.
    • Shaw, Douglas V. and Kirk D. Larson. 2002. Performance of Diamante with differing nursery location, nursery harvest date, and planting date. The Pink Sheet: California Strawberry Commission strawberry news bulletin 02-05, February 7, 2002.
    • Shaw, Douglas V. and Kirk D. Larson. 2002. Performance of Aromas plantings with differing nursery harvest date and planting date.
    • Larson, Kirk D. and Douglas V. Shaw. 2002. Management considerations for reducing pest and disease incidence in strawberry nurseries. Statewide Nursery Plant Quality Task Force Meetings, January, 2002.
    • Larson, Kirk D. and Douglas V. Shaw. Tratamientos de lavar e imersion para control de Colletotrichum acutatum en transplantes de fresa. Second annual Eurosemillas strawberry field day, February 20, 2002, Huelva, Spain.
    • Larson, Kirk D. and Douglas V. Shaw. 2002. Tratamientos de preplantacion para estimular el crecimiento vegetativo en plantas de fresa. Report prepared for the Spanish strawberry industry, June 2002.
    • Larson, Kirk D. and Douglas V. Shaw. 2002. Preplant treatments for enhancing growth of strawberry transplants. The Pink Sheet: California Strawberry Commission strawberry news bulletin 02-13, July 25, 2002.
    • Zalom, Frank, David Limburg, and Doug Shaw. 2002. Acaricide trials for Watsonville strawberries, Summer, 2001. The Pink Sheet: California Strawberry Commission strawberry news bulletin 02-15, August 20, 2002.
    • Shaw, Douglas V. and Kirk D. Larson. 2002. Advanced selection update: Performance of four day- neutral selections at the Watsonville Strawberry Research Facility with differing nursery harvest date and planting treatments. The Pink Sheet: California Strawberry Commission strawberry news bulletin 02-07, February 12, 2002.


    Progress 01/01/01 to 12/31/01

    Outputs
    Two short-day strawberry cultivars were released to the industry for commercial propagation and fruit production. The Ventana cultivar provides the best alternative for southern California and similar production systems; it produces large quantities of early-season fruit with weather tolerance and fruit quality superior to the target cultivar Camarosa. The cultivar Camino Real provides an alternative for central California growers and other similar environments that initiates fruiting late enough to escape winter weather, has superior disease resistance, fruit quality, and weather tolerance to the Camarosa cultivar in these regions. Nursery trials demonstrated that most strawberry runner plants infected with Verticillium are initially infected via infected mother plants through stolon transmission, and that post-nursery chilling can reduce expression of this disease for infected plants in some cultivars. Also, genetic evaluations demonstrated distinct differences in breeding value for Verticillium resistance dependent on selection methodology. Nursery treatments designed to clean stock heavily infected with Phytophthora cactorum were effective in reducing nursery symptoms but not in reducing infection levels in the runner plants produced by this stock. Nursery infestation trials for Phytophthora cactorum showed that the this disease causes relatively little problem for moderately resistant cultivars, serious compromise of productivity is only realized when the disease/resistance interaction causes severe plant mortality.

    Impacts
    Together the two cultivars released in 2001 are expected to replace the Camarosa cultivar worldwide. The benefits conferred by these two cultivars will thus affect approximately 50% of the fruit production around the world. The cumulative results for Verticillium resistance and treatment research have demonstrated multiple mechanisms of resistance. Results for research addressing Phytophthora cactorum in strawberry verify the importance of nursery clean stock measures in addition to cultural and genetic control measures.

    Publications

    • Luby, J. L., and D. V. Shaw. 2001. Does marker assisted selected selection make dollars and sense in a fruit breeding program. HortScience 36:872-879.
    • Shaw, D. V. and K. D. Larson. 2001. `Camino Real' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Larson, K. D. and D. V. Shaw. 2001. `Ventana' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • Gordon, T. R, S.C. Kirkpatrick, D. V. Shaw, and K. D. Larson. 2002. Differential Infection of Mother and Runner Plant Generations by Verticillium dahliae in a High Elevation Strawberry (Fragaria x ananassa Duch.) Nursery. HortScience (in press).
    • Shaw, D. V., T. R. Gordon, and K. D. Larson. 2002. Runner Plant Cold Storage Reduces Verticillium dahliae Kleb. Infection of Nursery Origin in Strawberry (Fragaria xananassa Duch.). HortScience (in press).
    • Limburg, David, Frank Zalom, and Doug Shaw. 2001. Watsonville and Bay Area Mite Control on Strawberries. The Pink Sheet: California Strawberry Commission strawberry news bulletin 01-01, February 6, 2001.


    Progress 01/01/00 to 12/31/00

    Outputs
    Cultural trials for strawberry demonstrated further opportunities for control of Phytophthora cactorum in susceptible cultivars using phosphorus acid compounds, with focus on nursery stock; a genetic screen for resistance to this pathogen in UC germplasm demonstrated a range of disease reaction from high susceptibility to nearly complete resistance. Studies of the consequences of methyl bromide alternatives for nursery fumigation demonstrated again that none of the available materials substitute directly for a combination of methyl bromide and chloropicrin. A seven-year trial was completed evaluating genetic x soil fumigation interaction for strawberry yield, comparing performance for plants cultivated in non-fumigated soil with plants established in soil treated each cycle with a combination of methyl bromide and chloropicrin. The results here support prior conclusions that cultivation over annual cycles in non-fumigated soils results in a steady decline in performance, and that genetics and breeding offer little opportunity for resolving problems associated with sub-lethal or competitive soil organisms encountered in non-fumigated soils. Development work as completed on two short-day cultivars and these are to be released to the industry in spring of 2001.

    Impacts
    Demonstration of economically viable methods for disease control have reduced risks for growers and stimulated their acceptance of a cultivar with substantial advantages in labor costs and consumer satisfaction; cultivars released in 1997 have increased to almost 30% of California acreage. The short-day cultivars released offer advantages in production efficiency and fruit quality, and may be adopted worldwide.

    Publications

    • Larson, Kirk D. and Douglas V. Shaw. 2000. Advanced selection update: Performance summary for winter-planted `C216'. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 00-5, April 14, 2000.
    • Shaw, Douglas V. and Kirk D. Larson. 2000. Advanced selection update: Performance summary for winter-planted `C213'. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 00-4, April 14, 2000.
    • Shaw, Douglas V. and Kirk D. Larson. 2000. Control of Phytophthora cactorum in Diamante plantings using Pre-plant Dips with Aliette. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 00-08, September 13, 2000.
    • Shaw, D. V. and K. D. Larson. 2001. Relative performance of strawberry genotypes over four years of cultivation on fumigated and non-fumigated soils. J. Amer. Soc. Hort. Sci. (In press).


    Progress 01/01/99 to 12/31/99

    Outputs
    Cultural trial for strawberry cultivars released in 1997 demonstrated opportunities for control of Phytophthora cactorum with phosphorus acid compounds. Eleven-year studies of the consequences of methyl bromide alternatives for production field fumigation and seven-year studies of nursery fumigation alternatives demonstrated that none of the available materials substitute directly for a combination of methyl bromide and chloropicrin. All fumigation alternatives were substantially better than fruiting field or nursery production without fumigation, but carryover studies indicated that the negative consequences of non-fumigated nursery and fruiting field soil are cumulative, perhaps indicating cumulative yield reductions of more than 20% with the best combination of alternatives. Genetic studies of root characteristics showed little if any genetic x soil fumigation interaction, and help explain the absence of detectible variation for adaptation specifically to performance on non-fumigated soils.

    Impacts
    The cultivars released by this program produce approximately 50% of the fruit in the world. Releases made in 1997 have now increased to over 20% of the California acreage; these have cut labor costs for harvest by almost 50% and increased consumer satisfaction with their fruit quality.

    Publications

    • Fort, S. B., and Shaw, D. V. 2000. Genetic analysis of strawberry root system traits in fumigated and nonfumigated soils I. Inheritance patterns of strawberry root growth and performance characteristics. J. Amer. Soc. Hort. Sci. (In press)
    • Fort, S. B., and Shaw, D. V. 2000. Genetic analysis of strawberry root system traits in fumigated and nonfumigated soils II. Relationships among root system and above-ground traits of strawberry seedlings. J. Amer. Soc. Hort. Sci. (In press)
    • Larson, K. D. and Shaw, D. V. 2000. Soil fumigation and runner plant production: a synthesis of four years of strawberry nursery field trials. HortScience (In press).
    • Larson, Kirk D. and Shaw, Douglas V. 1999. Mineral nutrition, plant spacing and yield of strawberry plants in southern California. The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-3, January 15, 1999.
    • Larson, Kirk D. and Shaw, Douglas V. 1999. Pomology progress report, South Coast Field Day 1999: Cultural Practices. March 10, 1999.
    • Larson, Kirk D. and Shaw, Douglas V. 1999. Advanced selection update: Performance of `C214', `C215, and `C216' compared with Camarosa in Southern California, 1999. The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-20, December 3, 1999.
    • Shaw, Douglas V., Larson, Kirk D. 1999. Pomology progress report, South Coast Field Day 1999: Cultivar Improvement. March 10, 1999.
    • Shaw, Douglas V., Larson, Kirk D. 1999. Management of Phytophthora cactorum in Diamante plantings with Aliette and Ridomil. The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-15, September 21, 1999.
    • Shaw, Douglas V., Larson, Kirk D. 1999. Performance of Diamante and Aromas in 1999 with differing high elevation nursery treatments in Santa Maria. The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-16, September 21, 1999.
    • Shaw, Douglas V., Larson, Kirk D. 1999. Advanced selection update: Performance of `C212' and `C213' compared with Camarosa in 1998 and 1999 production seasons. The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-19, December 3, 1999.
    • Shaw, Douglas V., Larson, Kirk D. 1999. Advanced selection update: Five short-day selections with adaptation for statewide production in California. The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-21, December 3, 1999.
    • Shaw, D. V. and Larson, K. D. 1999. A meta-analysis of strawberry yield response to preplant soil fumigation with combinations of methyl bromide-chloropicrin and four alternative systems. HortScience 34:838-845.
    • Zalom, F., Walsh, D., and Shaw, D. 1999. Acaricide efficacy and effects on predator mites in central coast strawberries, 1998.The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-2, January 12, 1999.
    • Zalom, F., Limburg, D., and Shaw, D. 1999. Acaricide trial for central coast strawberries, 1998.The Pink Sheet: California Strawberry Commission strawberry news bulletin 99-24, December 27, 1999.


    Progress 01/01/98 to 12/31/98

    Outputs
    Cultural recommendations for strawberry cultivars released in 1997 were refined, including recommendations for nursery harvest treatment and field mulch application. Seven-year studies in both the inheritance of root characters in different soil environments and tolerance to two-spotted spidermites were completed; cultural treatments were identified as the most likely solution to production problems in both cases. A ten-year summary and meta-analysis of results for soil fumigation alternatives demonstrated that none of the available materials substitute directly for a combination of methyl bromide and chloropicrin, although all are substantially better than propagation without fumigation. Collaborative research was demonstrated the consequences of chilling treatments on VERTICILLIUM DAHLIAE, and a project was initiated to investigate opportunities for obtaining resistance to PHYTOPHTHORA CACTORUM.

    Impacts
    (N/A)

    Publications

    • WALSH, D.W., ZALOM, F.G., AND SHAW, D.V. 1998. Interaction of the twospotted spidermite (ACARI: TETRANYCHIDAE) with yield of day-neutral strawberries in California. J. Econ. Entom. 91:1-8.
    • WALSH, D.W., ZALOM, F.G., AND SHAW, D.V. 1998. Interaction of twospotted spidermite (ACARI: TETRANYCHIDAE)feeding on fruit yield and concentration of foliar catechols and foliar proteins in an advanced cycle strawberry breeding population. Florida Entom. (IN
    • WALSH, D., SHAW, D., LARSON, K., AND ZALOM, F. 1998. El nino updated-nursery chilling and fall temperatures: importance to plantation establishment and mite susceptibility. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 98(3), Jan.
    • SHAW, D.V. AND LARSON, K.D. 1998. Cultivar update: Qualitative cultural recommendations for winter-planted Gaviota. The Pink Sheet: California Strawberry Commission News Bulletin 98(19), Sept. 9, 1998.
    • SHAW, D.V. AND LARSON, K.D. 1998. Cultivar update: Qualitative cultural recommendations for winter-planted Diamante. The Pink Sheet: California Strawberry Commission strawberry News Bulletin 98(20),
    • SHAW, D.V. AND LARSON, K.D. 1998. Cultivar update: Qualitative cultural recommendations for winter-planted Aromas. The Pink Sheet: California Strawberry Commission Strawberry News Bulletin 98(21),
    • SHAW, D.V. AND LARSON, K.D. 1998. Cultivar update: Qualitative cultural recommendations for winter-planted Pacific. The Pink Sheet: California Strawberry Commission Strawberry News Bulleton 98(22),


    Progress 01/01/97 to 12/01/97

    Outputs
    Planting stock for one short-day cultivar (June bearing) and three day-neutral (everbearing) cultivars were released to California nurseries; approximately seven million plants of each cultivar were produced and planted this fall. Efforts to develop strawberry cultivars resistant to VERTICILLIUM DAHLIAE continued with demonstration of the consistency of response over test locations and inoculum densities. The inheritance of strawberry root characters was further evaluated in fumigated and non-fumigated soils using selection response criteria, and these studies verified previous conclusions: variation for root characters is present but genetic differences that impact productivity are expressed consistently over fumigation environments. Also, root characters were highly correlated with above ground indicators of vegetative growth, suggesting that time-consuming root assessments may be unnecessary. Long-term evaluation of the interaction of weak inbreeding and strong selection demonstrate the power of genetic change to overcome problems of moderately related germplasm.

    Impacts
    (N/A)

    Publications

    • SHAW, DOUGLAS V., GUBLER, W.D., AND HANSEN, JOHN. 1997. Field Resistance of California Strawberries to VERTICILLIUM DAHLIAE at Three Conidial Inoculum Concentrations. HortScience 32:711-713.
    • SHAW, DOUGLAS V. 1997. Trait mean depression for second- generation inbred strawberry populations with and without parent selection. Theoret. Appl. Genet. 95:261-264.
    • SHAW, DOUGLAS V., GUBLER, W.D., et al. 1997. Response to Family Selection for Field Resistance to VERTICILLIUM DAHLIAE in California Strawberries. J. Amer. Soc. Hort. Sci. 122:653-655.
    • SHAW, D.V. 1997. 'Gaviota' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • SHAW, D.V. 1997. 'Aromas' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • SHAW, D.V. 1997. 'Diamante' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).
    • SHAW, D.V. 1997. 'Pacific' strawberry cultivar. United States Patent Declaration and Description (US Plant Patent pending).


    Progress 01/01/96 to 12/30/96

    Outputs
    Germplasm development efforts for strawberry cultivars resistant to VERTICILLIUMDAHLIAE were evaluated using divergent selection and short-term responses were consistent with predicted values, although further response seems limited by the severity of infection under currently available inoculation procedures. The inheritance of strawberry root characters was determined in fumigated and non-fumigated soils and the relationship between root growth and quality in each soil environment was related to productivity through genetic correlations and path analysis. Preliminary thresholds for Two-spotted spider mite (Acari: Tetranychidae) were estimated as between 0.5 and 1.5 mites per leaf using regression analysis of yield depressions on infestation data from 6 years, and genetic variation for resistance to spidermites was found to be expressed only under horticultural treatments that condition low plant vigor. Disclosures for one short-day cultivar (June bearing) and three day-neutral (everbearing) cultivars were finalize and planting stock prepared for release.

    Impacts
    (N/A)

    Publications

    • WALSH, D, LARSON, K, ZALOM, F, SHAW, D, AND TOSCANO, N. 1995. Chandler: Timing of two-spotted mite control influence on fruit production, size, and number for fall transplanted strawberries in Southern California. The Pink Sheet: California LARSON, KIRK D.
    • AND SHAW, DOUGLAS V. 1996. Nursery and field fumigation treatments and yield of Chandler. The Pink Sheet: California Strawberry Commission Bulletin 96-3, February 5, 1996. 2p.
    • WALSH, D., ZALOM, F., SHAW, D., AND WELCH, N. 1996. Strawberry cultivar, soil fumigation, spider mite interrelationship field trials - mite abundance and effect on fruit yield. The Pink Sheet: California Strawberry Commission Bulletin96-4,.
    • WALSH, DOUGLAS B., ZALOM, FRANK G., SHAW, DOUGLAS V., AND WELCH, NORMAN C. 1996.Effect of strawberry plant physiological status on the translaminar activity of Avermectin B1 and its efficacy against the Two-spotted spider mite (Acari: Tetr WALSH, DOUGLAS B., ZALOM, FRANK G., WELCH, NORMAN C., PICKEL, CAROLYN, AND SHAW,DOUGLAS V. 1996. Preplant cold storage on strawberries: effects on mite resistance, plant vigor, and yield. Jour. Econ. Entomol. (In press).
    • LARSON, KIRK D. AND SHAW, DOUGLAS V. 1996. Soil fumigation, fruit production andseasonal dry matter partitioning of field-grown strawberry plants. J. Amer. Soc.Hort. Sci. (In press).


    Progress 01/01/95 to 12/30/95

    Outputs
    Germplasm potentially useful for developing strawberry cultivars adapted to non-fumigated soils was evaluated for resistance to VERTICILLIUM DAHLIAE and COLLETOTRICHUM SPP, and for general response to fumigation. Substantial variation for resistance to both major pathogens was detected in the California germplasm and no supplemental variation was identified in exotic sources. Little or no genetic fumigation interaction was detected in the absence of lethal pathogens, for California near market selections, California seedling populations, cultivars selected for perennial systems, or seedlings from exotic cultivars. Wilt caused by VERTICILLIUM DAHLIAE was shown to be inoculum-density dependent, but genotypic rankings remained similar regardless of infestation level. There appears to be no compelling reason for infusion of exotic resistance germplasm into the California population. Further, the general yield response to fumigation appears to be common to all commercial strawberry germplasm regardless of origin, and no short-term genetic solutions to this problem appear possible.

    Impacts
    (N/A)

    Publications


      Progress 01/01/94 to 12/30/94

      Outputs
      Studies of the potential for breeding strawberry cultivars adapted to non-fumigated soils were extended to include genetic evaluations of root growth in fumigated and non-fumigated soils and a search for resistance to VERTICILLIUM DAHLIAE. Root weight and appearance scores were moderately heritable and were generally correlated with performance traits. As for previous experiments, little or no genetic fumigation interaction was detected in the absence of lethal pathogens. A survey based on inoculation of 41 California genotypes and the offspring of 23 of these genotypes indicated that most of the California germplasm is highly susceptible to wilt caused by VERTICILLIUM DAHLIAE. However, a broad range of intermediate resistance was detected, and about 10% (4/41) of the genotypes surveyed had resistance scores superior to the mean of that for six non-California types chosen as a resistant check. Plot-mean heritabilities estimated using genotypic, full-sib family, and offspring-parent analyses ranged from 0.45 to 0.79. Comparison of different heritability estimates and variance components suggest that about half of the genotypic variance detected is due to the additive effects of genes. There appears sufficient variation within the California population to proceed with an effective selection program, although this will depend on the recovery of transgressive segregants from superior parents, as even relatively tolerant types showed some symptoms.

      Impacts
      (N/A)

      Publications

      • SHAW, D.V. AND LARSON, K.D. 1994. Comparison of five recently released short-day cultivars with summer-planted Pajaro at the Watsonville res. fac. in 1993. The Pink Sheet, Calif. Straw. Comm. Bul., 2 p.
      • WALSH, D.B., ZALOM, F., SHAW, D.V., AND WELCH, N. 1994. Strawberry cultivar, soil fumigation, spider mite interrelationship. The Pink Sheet, Calif. Straw. Comm. Bul., 2 p.
      • RARIDEN, J.M. AND SHAW, D.V. 1994. Performance of North American strawberry cultivars under conditions mimicking California production systems. J. Amer. Soc. Hort. Sci. 119:1034-1038.
      • SHAW, D.V. 1994. Comparison of ancestral and current-generation inbreeding in an experimental strawberry population. Theoret. Appl. Genet. in-press.
      • LARSON, K.D. AND SHAW, D.V. 1994. Relative performance of strawberry genotypes in fumigated and nonfumigated soil. J. Amer. Soc. Hort. Sci. in-press.
      • LARSON, K.D., SHAW, D.V., AND STERRETT, J. 1994. Soil fumigation and runner production in a high-elevation strawberry nursery in 1993. The Pink Sheet, California Strawberry Commission Bulletin, 2 p.
      • SHAW, D.V. AND LARSON, K.D. 1994. Performance of high elevation 'Selva', 'Seascape', & 'Sunset' at the Watsonville res. fac. in 1992 & 1993 with immediate & mid-winter tarp appl. The Pink Sheet, Calif. Straw. Comm. Bul., 2 p.


      Progress 01/01/93 to 12/30/93

      Outputs
      Disclosures were finalized for five short-day and one day-neutral cultivar, and efforts continued to resolve cultural treatments for optimizing their productivity. The first large-scale commercial plantings of these cultivars were established in fall of 1993, and initial feedback has been promising. Preliminary studies of the potential for breeding cultivars adapted to non-fumigated soils were completed. These studies demonstrated little or no genetic x fumigation interaction, for either highly selected genotypes or segregating seedling populations, at least in the absence on lethal pathogens. This result suggests that testing of genetic materials on non-fumigated soil would confer an advantage only when screening for lethal pathogens, and specific inoculation trials are likely to be superior alternatives for that purpose. Yield reductions in non-fumigated soils were 40-50% in the absence of lethal pathogens, so together with the failure to detect specific adaptational mechanisms, these results indicate that the chance of genetic improvement serving as an alternative to soil treatments is remote at best.

      Impacts
      (N/A)

      Publications

      • SHAW, D.V. and HANSEN, J.J. 1993. The inheritance of vegetative growth traits in strawberries (FRAGARIA x ANANASSA) grown at low temperatures and their relationship to field productivity. Theor. Appl. Genet. 87:170-176.
      • SACKS, E.J. and SHAW, D.V. 1993. Optimum allocation of objective color measurements for evaluating fresh strawberry fruit. J. Amer. Soc. Hort. Sci. (in-press).
      • HANCOCK, J.F., CALLOW, P.A., and SHAW, D.V. 1993. Random amplified polymorphic DNA (RAPDs) in the cultivated strawberry, FRAGARIA x ANANASSA, J. Amer. Soc. Hort. Sci. (in-press).
      • BRINGHURST, R.S., SHAW, D.V., and VOTH, V. 1993. 'Cuesta' strawberry cultivar. United States Patent Declaration and Description (Patent Pending).
      • BRINGHURST, R.S., SHAW, D.V., and VOTH, V. 1993. 'Sunset' strawberry cultivar. United States Patent Declaration and Description (Patent Pending).
      • VOTH, V., SHAW, D.V., and BRINGHURST, R.S. 1993. 'Anaheim' strawberry cultivar. United States Patent Declaration and Description (Patent Pending).


      Progress 01/01/92 to 12/30/92

      Outputs
      Disclosures were initiated for six new strawberry cultivars: five of the selections are short-day types and one is a weak-moderate day neutral. Several of the short-day selections have adaptation in both southern and northern regions of California, whereas the day-neutral selection is adapted from Santa Maria north. Significant and large genetic correlations were detected between plant cross-sectional diameter and production traits in segregating strawberry seedling populations. Several vegetative traits were identified in seedlings and in nursery runner-plant stock that could be used to obtain indirect selection response for yield and production pattern. Genetic variation for growth response at minimal growing temperatures was detected in segregating seedlings adapted to California, and in a broader germplasm sample that included a range of North American cultivars. No temperature x genetic interactions were detected in any of these experiments; this suggests that differences of regional adaptation in strawberries is a consequence of complex interactions rather than a simple response to growing temperature. Also, traits scored in controlled temperature chambers were well correlated with traits scored in the field. Investigations of color change in strawberry fruit during post-harvest storage demonstrated that both the absolute differences and the relative rankings of different genotypes remain stable over realistic storage periods.

      Impacts
      (N/A)

      Publications

      • SHAW, D.V. 1992. Genetic correlations between vegetative growth traits and productivity at different within-season intervals for strawberries (FRAGARIA x ANANASSA). Theor. Appl. Genet. (in-press).
      • RARIDEN, J.M. and SHAW, D.V. 1992. Vegetative attributes of North American cultivars with differing temperature regimes. Presented at: 2nd International Strawberry Symposium, September, 1992, Baltimore, MD, Acta Horticulturae. (In press).
      • SACKS, E.J. and SHAW, D.V. 1992. Color change in fresh strawberry fruit stored at OC. HortScience (In press).


      Progress 10/01/86 to 09/30/91

      Outputs
      Research conclusions were obtained that addressed the following: 1) quantitative genetics and selection efficiency for strawberry production traits, 2) inheritance of strawberry quality traits, 3) pest and disease resistance in strawberry, and 4) biometrical and quantitative genetic analyses of clonally propagated crops. Experimental results demonstrated that genetic variance parameters for fruit yield, fruit size and commerical appearance estimated for current populations do not differ from ancestral levels. Also, no correspondence was detected between pedigree inbreeding coefficients and performance. Selection strategies were optimized for production traits in current strawberry populations using information from relatives, and information obtained about the temporal expression of the genetic and environmental effects that condition production traits within a single season. Genetic x location interactions and genetic x propagule type interactions were both found to be important for yield, but not for most other production and quality traits. Parameters were estimated to describe the quantitative inheritance of flavor and color traits, and these results were verified using selection experiments. Together, the empirical and analytical results have been used to redesign the breeding, testing, and selection procedures used by the California Strawberry Improvement program.

      Impacts
      (N/A)

      Publications

      • SHAW, D.V. 1991. Genetic variation for objective and subjective measures of fresh fruit color in strawberries. Journal of the American Society for Horticultural Science 116(5):894-898.
      • SHAW, D.V. 1991. Recent advances in the genetics of strawberry, pp. 76-83, In: A. Dale and J.J. Luby (eds), The Strawberry Into the 21st Century.
      • SHAW, D.V. 1991. Performance of summer planted 'Seascape' at the Watsonville Research Facility. California Strawberry Advisory Board, 2 pp.


      Progress 01/01/90 to 12/30/90

      Outputs
      Studies were continued to test the genetic correspondence between traits expressed in plants propagated sexually(as seedlings) and vegetatively(as runners), both within and between test locations. Performance rankings for yield and appearance score were changed more by propagule type than by location, and the correspondence between yield in seedlings and runner plants was especially low. Fruit quality characteristics had comparatively good correspondence across locations and propagation types. These results suggest that selection using independent culling for separate traits at separate programmatic stages will improve selection efficiency. Genetic dissection of traits related to flavor quality were continued, and genotypes previously tested for clonal value were tested for breeding value. Response to selection was obtained for high soluble solids and both high and low titratable acids breeding value. These results, together with previous experiments, suggest that genetic X location interactions have large consequences for solids but not for acids.

      Impacts
      (N/A)

      Publications

      • WEINBAUM, S.A, SHAW, D.V., AZARI, R. and MURAOKA, T.T. 1990. Mass selection of walnut rootstocks using response surface methods to correct for environmental trends. Euphytica 46:227-235.
      • SHAW, D.V. 1990. Response to selection and associated changes in genetic variance for soluble solids and titratable acids contents in strawberries. Journal of the American Society for Horticultural Science 115(5):839-843.
      • SHAW, D.V. 1990. Performance summary for winter planted Seascape, Capitola and Selva at the Watsonville Research Facility. California Strawberry Advisory Board, 2 pp.
      • SHAW, D.V. 1990. Genetics and varietal improvement of strawberries. Comprehensive Research on Strawberries Annual Report, Feb. 1, 1990-Jan. 31, 1991 to the California Strawberry Advisory Board. 17 pp.
      • SHAW, D.V. 1990. Summary I. Strawberry breeding in California. Sugar Cane Plant Breeding Workshop, Dec. 10, 11, and 12, 1990, Brisbane, Australia. 2 pp.
      • SHAW, D.V. 1990. Summary II. Genotype x environment interaction of strawberry cultivar development. Sugar Cane Plant Breeding Workshop, Dec. 10, 11, and 12, 1990, Brisbane, Australia. 2 pp.


      Progress 01/01/89 to 12/30/89

      Outputs
      Experiments were conducted to investigate opportunities for improving selection efficiency for production and quality traits in strawberries. Selection methods that employ part-record procedures were evaluated, and results demonstrated temporal differences in genetic and environmental variance components that lead to optimum efficiency with selection based on part-season records. Preliminary studies were conducted to determine the genetic correspondence for traits expressed in plants propagated sexually (as seedlings) and vegetatively (as runners). These comparisons suggest that genetic correlations are less than 1.0 for important production traits. Further recommendations as to the value of indirect selection of seedlings for genotypes intended as vegetatively propagated cultivars depends on incorporation of information regarding other genotype x interactions. The correspondence of genetic effects in seedlings with their vegetatively propagated parents identified both test location and cultural treatments as important sources of interaction variance.

      Impacts
      (N/A)

      Publications

      • SHAW, D.V. 1989. Variation among heritability estimates for strawberries obtained by offspring-parent regression with relatives in separate environments. Euphytica 44:157-162.
      • SHAW, D.V. 1989. Genetic parameters and selection efficiency using part records for production traits in strawberries. Theoret. Appl. Genet. 78:560-566.
      • SHAW, D.V., BRINGHURST, R.S. and VOTH, V. 1989. Genetic parameters estimated for an advanced-cycle strawberry breeding population at two locations. J. Amer. Soc. Hort. Sci. 114:823-827.


      Progress 01/01/88 to 12/30/88

      Outputs
      Populations of seedlings were established from crosses among genotypes selected for varietal potential on an individual-plant basis, and genotypes selected specifically for breeding value using quantitative information from relatives. In addition, these genotypes were evaluated in commercial performance trials established using clonal materials(runners). Whereas little seedlings from parents selected using information from relatives averaged 30% greater yeild and 15% larger fruit than seedlings selected for varietal performance, suggesting that quantitative selection procedures can be of substantial value in choosing parents for subsequent generations. Divergent selection for soluble solids and organic acids was continued using a population of 800 seedlings from crosses among genotypes previously selected for high and low phenotypic expression of these traits. Seedlings from High x Low crosses were intermediate for both traits, but were highly skewed towards the low parent value for solids. Offspring means for solids corresponded well with the breeding values orginally calculated for parental selection, but less well with observations on clonally tested genotypes; both correspondences were high for acids. These results support pervious findings, and suggest that breeding for fruit flavor will be best approached through manipulation of organic acids.

      Impacts
      (N/A)

      Publications

      • SHAW, D. V. (1988). Genotypic variation and genotypic correlations for sugars and organic acids of strawberries. J. Amer. Soc, Hort. Sci. 113:770-774.
      • SHAW, D.V. In press. Variation among heritability estimates for strawberries obtained by offspring-parent regression with relatives raised in separate environments. Euphytica accepted Oct 12 (1988).
      • SHAW, V. BRINGHURST, R. S. and VOTH V. In press. Genetic parameters estimated for an advanced-cycle strawberry breeding population at two locations. J. Amer. Soc. Hort. Sci. accepted Oct 28, (1988).
      • SHAW, D.V. BRINGHURST, R.S., and VOTH, V (1987). Genetic variation for quality traits in an advanced cycle breeding population of strawberries. J. Amer. Soc. Hort. Sci. 112:699-702.


      Progress 01/01/87 to 12/30/87

      Outputs
      Breeding populations of commercial strawberries were evaluated for genetic and environmental variance parameters using field trials in two years and two locations. Significant and potentially useful genetic variation was detected for yield, fruit size, resistance to common leaf spot (Ramularia spp.) and several quality characters. Importantly, the relative contributions of genetic and environmental effects changed during a single production season. Changes in the relative contribution of additive and dominance genetic effects during a single season suggests temporal variation in the genes that condition several production traits. Large genetic x environmental interaction effects were detected for yield and quality characters. Genes that condition yield interact primarily with locational differences; quality traits are conditioned by genes that interact with environmental effects that change during a single production season. Field evaluations of leaf spot resistance were consistant over years, provided that evaluation was conducted during periods of heavy natural infection. No correlations were detected between cross performance or cross stability and inbreeding coefficients estimated using pedigree analysis, indicating that small increments of inbreeding will not seriously limit opportunities for achieving genetic gain.

      Impacts
      (N/A)

      Publications

      • SHAW, D.V., BRINGHURST, R.S. and VOTH, V. 1987. Genetic variation for quality traits in an advanced-cycle breeding population of strawberries. J. Amer. Soc. Hort. Sci. 12(4):699-702.
      • SHAW, D.V. 1987. Genetics and varietal improvement of strawberries. California Strawberry Advisory Board Comprehensive Research on Strawberries: Annual Report (1986). 18 pp.
      • SHAW, D.V., BRINGHURST, R.S. and VOTH, V. 1988. Genetic variation for resistance to leaf spot (Ramularia tulasnei) in California Strawberries. J. Amer. Soc. Hort. Sci. (in-press).
      • SHAW, D.V. 1988. Genetics and varietal improvement of strawberries. California Strawberry Advisory Board Comprehensive Research on Strawberries: Annual Report (1987). 10 pp.