New Directions for Strawberry Research in the 2020s

ABSTRACT

Advances in the areas of strawberry breeding, production, and pest management are the subjects of new research presented every four years at the North American Strawberry Symposium (NASS). The NASS is an international conference hosted by the North American Strawberry Growers Association; the 2023 symposium was held in San Luis Obispo, California, USA. This editorial review is intended to serve as an introduction to the research topics and institutions represented at the 2023 NASS, and the corresponding Special Article Collection published in the International Journal of Fruit Science. The previous three NASS conferences examined extending production seasons, tailoring production systems to growing environments, and promoting soil health. The 2023 NASS explored new developments in genomics-informed breeding, production automation, and alternative pest management among other topics of keen interest for the strawberry industry. There was strong representation from the host state of California, including research teams from the Cal Poly Strawberry Centre, the University of California Davis, and several private agri-tech ventures. As well, presenters from Pakistan, South Africa, Italy, and Australia brought a global perspective to current breeding, production, and pest management challenges. This NASS 2023 Special Article Collection highlights the major themes of pesticide reduction, data science, and climate change, which are key targets for applied strawberry research in the 2020s.

KEYWORDS:

• Strawberry
• pathogens
• pests
• cultivars
• automation
• biocontrol
• climate

Introduction: The North American Strawberry Symposium

The North American Strawberry Symposium (NASS) is an international conference hosted every four years by the North American Strawberry Growers Association (NASGA) (www.nasga.org). The conference is attended by strawberry industry stakeholders of all levels including suppliers, propagators, producers, and marketers, as well as researchers, extensions specialists, and students. Guests and presenters arrive from the United States, Canada, Mexico, and around the world (Figure 1). The goal is to share and discuss the newest research findings and directions that will support long-term growth and development in the global strawberry industry.

Figure 1. Map of research institutions represented by oral and poster presenters at the 2023 north American strawberry symposium. Research areas by presentation are indicated by color, and number of presentations per location are indicated by dot size as shown in the legend above. The conference host city, San Luis Obispo, California, is represented by a black square. The map template was obtained from freevectormaps.com.

The 2023 NASS was held in San Luis, Obispo, California, from March 7–10, 2023. The symposium was chaired by United States Department of Agriculture (USDA) strawberry breeder Dr. Kim Lewers, who curated a program of world class experts and emerging scientists across several disciplines. The 2023 NASS featured posters and presentations in the core strawberry research areas of genetics and breeding, production and propagation, and pest and disease management. There was also a special focus on disease resistance breeding, data-driven production technologies, and alternative pest management strategies. The keynote speakers were Dr. Gerald Holmes, director of the Cal Poly Strawberry Center, and Mark Bolda, Farm Advisor for the University of California Agricultural and Natural Resources.

The purpose of this editorial article is to launch the 2023 NASS Special Article Collection. The research groups and topics selected for the 2023 NASS are introduced in the following sections. Shortly ahead of the conference, all presenting authors were invited to submit their research for publication in the International Journal of Fruit Science (IJFS). Here we highlight some of the key advances anticipated in the 2023 article collection, as well as past findings, and potential future directions for applied research in strawberry.

NASS Proceedings

For the past twelve years, scientific proceedings of the NASS have been published as special issues in the IJFS (Taylor & Francis, London, UK). The 2011, 2015, and 2019 NASS Proceedings can be found online at www.tandfonline.com/journals/wsfr20/special-issues.

The NASS special issues of IJFS have covered a broad spectrum of research in the areas of genetics and breeding, production and propagation, pest and disease management, and fruit quality. These topics are of perennial interest to strawberry researchers and stakeholders, as the industry will always need new tools to increase productivity, combat abiotic and biotic crop stresses, and market more desirable berries. Along with the core research, every four years has brought at least one special area of focus. The early 2010s saw an emphasis on diverse global production systems (summarized by Takeda et al., 2013). The mid 2010s focused on soil disinfestation technologies as alternatives to chemical fumigants (e.g., Fennimore and Goodhue, 2016; López-Aranda et al., 2016; Mazzola et al., 2016). The late 2010s emphasized geographic expansion and season extension, pest management and yield improvement (e.g., Dowling and Schnabel, 2020; Rao et al., 2020; Renkema et al., 2020; Whitaker and Fan, 2020). Research published following the 2023 NASS is expected to address the critical issue of climate change, with specific focus on data science and alternative pest management.

In 2023, the NASS will take a new approach for science publications. All presenting authors have been invited to submit their manuscripts to the IJFS as usual. However, instead of a special issue, the journal has created a Special Article Collection entitled “2023 North American Strawberry Symposium.” Associate editors B. Amyotte and J. Samtani will assign articles submitted by NASS presenters to this article collection. There will be no separate issue of the journal. Instead, the articles categorized under the Special Article Collection will be posted to a dedicated page on the IJFS website. The advantage for authors is that the papers will be full peer-reviewed publications rather than proceedings, and they will be published without delay at the time of acceptance. This is the first Special Article Collection for IJFS, and the goal is to efficiently promote novel strawberry research on an international scale.

Industry Trends

The 2023 NASS was hosted in San Luis Obispo, California. California is the largest strawberry producing state in the USA, responsible for $3.0 Billion of the $3.4 Billion total domestic crop value in 2021 (USDA, 2022). State universities in California are world leaders in strawberry research and development. For example, the breeding program at the University of California Davis has released several of the most impactful modern cultivars, including “Albion”, “Camino Real”, and “Fronteras” (Shaw & Larson, 2001, 2004; Larson and Shaw, 2014). The breeding program and their industry stakeholders are supported by a strong production research network. Mark Bolda, Farm Advisor for the University of California Agricultural and Natural Resources, strongly emphasized the value and importance of direct relationships between strawberry producers and researchers in his keynote address at the 2023 NASS. To this end, the Cal Poly Strawberry Center was established in 2013 as a partnership between California Polytechnic State University and the California Strawberry Commission, with a mandate to research sustainable strawberry production (https://strawberry.calpoly.edu). Their areas of focus include plant pathology, entomology, and automation (e.g., Fink et al., 2020; Palmer and Holmes, 2021; Wells et al., 2020). Strawberry Center director Dr. Gerald Holmes presented an overview of industry trends and research directions from the California perspective.

Genetics & Breeding

Genetics and breeding are a core research area for the NASS. In 2023, presentations were made by the major breeding programs at the University of California Davis and the University of Florida, as well as several other programs in the USA, Canada, and Italy (Figure 1, Table 1). The breeders discussed new and ongoing cultivar objectives, selection methods, and the roles of genomics and phenomics in their respective programs. The genetics team from UC Davis presented new genomic structure discoveries from haplotype-phased genomes, and genetic strategies to improve yield. The University of Florida team provided a summary of the molecular tools currently applied in the breeding program, and discussed advances in breeding for resistance to Neopestalotiopsis and Macrophomina diseases (Table 1).

Table 1. List of oral and poster presentations at the 2023 North American strawberry symposium, San Luis Obispo, CA, USA.

Primary Institution	Authors	Title
Industry and Research Overview
University of California Agriculture and Natural Resources Watsonville, CA, USA	M. Bolda	Growers and Researchers: Working Together for a Better Future in Strawberries
Cal Poly Strawberry Center San Luis Obispo, CA, USA	G.J. Holmes	The California Strawberry Industry: Current Trends and Future Prospects
United States Dept. of Agriculture Poplarville, MS, USA	K. Lewers, J. Munyaneza, J. Okamuro, T. Rinehart, T. Widmer	USDA-ARS Investment in Strawberry Research
Genetics and Breeding
University of California Davis Davis, CA, USA	S.J. Knapp, D.D. Pincot, M.J. Feldmann, G.S. Cole	Genetic Gains Underpinning the Strawberry Green Revolution: Where to Next?
University of California Davis Davis, CA, USA	M.J. Feldmann, M.A. Hardigan, D.K. Seymour, C.M. Lopez, C.B. Acharya, R.A. Famula, G.S. Cole, S.J. Knapp	Islands of Diversity, Polymorphism Deserts: Haplotype-Phased Genomes Shed Light on Domestication-Driven Heterosis and Reshaping of Genetic Variation in Octoploid Strawberry
University of California Davis Davis, CA, USA	G.S. Cole, C.M. Lopez Ramirez, O. Gonzalez-Benitez, R. Famula, D.D. Pincot, S.J. Knapp	Five High Yielding Fusarium Wilt Resistant Cultivars for Short-Day, Day-Neutral, and Summer-Plant Production
University of California Davis Davis, CA, USA	M.J. Feldmann, D.D. Pincot, M.V. Vachev, M. Bjornson, R.A. Famula, G.S. Cole, S.J. Knapp	Accelerating Genetic Gains for Resistance to Verticillium Wilt Through Phenotypic and Genomic Selection
University of California Davis Davis, CA, USA	N.P. Jiménez, M.J. Feldmann, R. Famula, D.D. Pincot, M. Bjornson, G.S. Cole, S.J. Knapp	Harnessing Underutilized Gene Bank Diversity and Genomic Prediction of Cross Usefulness to Enhance Resistance to Phytophthora cactorum in Strawberry
University of California Davis Davis, CA, USA	M.V. Vachev, D.D. Pincot, M. Bjornson, M.J. Feldmann, G. Coaker, S.J. Knapp	Resistance to Fusarium Wilt in the Heirloom Cultivar “Earliglow” is Conferred by Dominant Duplicate Epistasis Between Unlinked Resistance Genes on Chromosome 2B in Strawberry
University of California Davis Davis, CA, USA	D.D. Pincot, M.J. Feldmann, M.A. Hardigan, R.A. Famula, G.S. Cole, S.J. Knapp	Linkage Mapping as a Classical Approach to Validate and Correct Genomic Metadata
University of California Davis Davis, CA, USA	N.P. Jiménez, M. Bjornson, M.J. Feldmann, S.J. Knapp	Genetic Regulation of Pectin Lyase Profoundly Affects Fruit Firmness in Strawberry
California Berry Cultivars French Camp, CA, USA	K. VandenLangenberg	How we Breed Strawberries at California Berry Cultivars, LLC
University of Florida Wimauma, FL, USA	V. Whitaker, C. Dalid, S. Verma, L. Osorio, S. Lee	An Overview of UF Strawberry Cultivars and Breeding Methods
University of Florida Wimauma, FL, USA	E. Alam, S. Lee, V.M. Whitaker	Recent Advances in Breeding for Resistance to Neopestalotiopsis sp. and Macrophomina phaseolina in Strawberry
University of Florida Wimauma, FL, USA	C. Dalid	High-Throughput Field Phenotyping and its Application in the UF Strawberry Breeding Program
University of Florida Wimauma, FL, USA	S. Lee	Molecular Breeding Tools and Applications to Improve Strawberry Varieties
University of Florida Wimauma, FL, USA	J.H. Kim, V.M. Whitaker, S. Lee	Genomic Characterizations of Resistance to Bacterial Angular Leaf Spot in Strawberry
University of Florida Wimauma, FL, USA	Y.J. Jang, Y. Oh, C. Dalid, C.M. Yoo, V.M. Whitaker, S. Lee	DNA Marker-Assisted Seedling Selection to Improve Strawberry Varieties
University of Florida Wimauma, FL, USA	M. Porter, X. Song, V. Whitaker, S. Lee, Z. Fan, Y. Wang	Strawberry Flavor Improvement through Molecular Breeding
University of Wisconsin River Falls River Falls, WI, USA	B. Smith	Breeding Strawberries for USDA Hardiness Zone 3B
North Carolina State University Raleigh, NC, USA	B. Haynes, G. Fernandez, P. Perkins-Veazie	Anthocyanin in Strawberries: Content and Profile in North Carolina Strawberry Germplasm
Pairwise Durham, NC, USA	Tom Spaulding	Conscious(TM) Foods: How Pairwise is Innovating a New Era in Produce
Agriculture and Agri-Food Canada Kentville, NS, Canada	B. Amyotte	Update from the Agriculture Canada Strawberry Breeding Program
Consorzio Italiano Vivaisti (CIV) Comacchio, FE, Italy	J. Aelterman	40 Years of Strawberry Breeding − 40 Years of Hydroponic Production
Production and Propagation
University of California Agriculture and Natural Resources Watsonville, CA, USA	M. Bolda	The Effect of Bare Root Transplant Size and Early Season Flower Removal in Day Neutral Strawberry
University of California San Luis Obispo, CA, USA	M. Battany	Measuring Temperature Inversions to Optimize Response to Risk of Frost and Spray Drift
The University of Agriculture Peshawar Peshawar, Pakistan	N. Bostan, M. Sajid	Improving Phenological and Yield Traits of Strawberry by Inclusion of Phosphorus and Potassium
The University of Agriculture Peshawar Peshawar, Pakistan	N. Bostan, M. Sajid	Effect of Shade Levels and Pre-Transplant Vernalization Duration on Biochemical and Vegetative Traits of Strawberry Plants
Agricultural Research Institute, Swat, Pakistan	N. Bostan, M.A. Rauf, K. ur Rahman, M. Ibrahim, M. Ayaz, Roshan Ali, F. Rabi, J. Rahman, W. Bilal	Strawberry Production in Pakistan
University of California Davis Davis, CA, USA	R. Mikkelsen	Reexamining Strawberry Nutrition and its Impact on Fruit Yield and Quality
California Strawberry Commission Watsonville, CA, USA	M. Ahmadi, A. Atefi, M. Ramzanpour, J. Lin	Deep Learning Based Strawberry Runner Detection
California Strawberry Commission Watsonville, CA, USA	G. Schaap, G. Speth, W. Kramer, J. Wells, C. Fink, J. Lin	Automated Hoop House Arch Removal
California Strawberry Commission Watsonville, CA, USA	W. Kraemer, J. Lin, M. Ahmadi	Plastic Mulch Hole Burning and Cutting for Strawberry Planting
Advanced.Farm Davis, CA, USA	P. Ferguson	Moving Past the Promo Videos: How Advanced.Farm Robots Picked over 100,000 Strawberries in One Day
PickTrace Glendale, CA, USA	H. Steed	Using Field Data to Improve Labor Costs
University of Florida Wimauma, FL, USA	X. Zhao, J. Li, J.K. Brecht, J. Kim	Biostimulant Application for Improving Organic Strawberry Production
University of Florida Wimauma, FL, USA	X. Zhao, J. Li, S. Agehara, J.K. Brecht	Influence of Different Nutrient Management Programs on Organic Strawberry Plant Growth, Yield, and Fruit Quality
University of Florida Wimauma, FL, USA	K. Vondracek, I. Whitaker, S. Lee, T. Liu	Effects of Exogenous Gibberellic Acid Application on Strawberry Development
University of Florida Wimauma, FL, USA	J. St Fort, C.A. Chase, V. Sharma	Reducing Water Use in Florida Strawberry Production with Low-Volume Sprinkler Systems
North Carolina State University Raleigh, NC, USA	M. Hoffmann, R. Hernández, G. Fernandez, H. Schweizer, B. Jackson, D. Tregeagle, C. Kubota, J. Boldt, E. Durner, P. Nitzsche, C. Goméz, J. Samtani, C. Weber, S. Agehara, O. Daugovish, G. Galdi, R. Goodhue, Z. Lui, G. Holmes	Strawberry Precise Indoor Propagation (PIP): The Development and Integration of Next-Generation Propagation Strategies to Increase Resilience of the US Strawberry Supply Chain
North Carolina State University Raleigh, NC, USA	B. Shur, B. Jackson	Recent Advances and Trends in the Soilless Production of Strawberries
North Carolina State University Raleigh, NC, USA	T. Adhikari, F. Louws	Accelerating Microbiome for Sustainable Management Solutions for Strawberry
North Carolina State University Raleigh, NC, USA	B. Shur, B. Jackson	Substrate Physical Properties Determined by Component Particle Size
North Carolina State University Raleigh, NC, USA	M. Palmer, S. Humphrey, R. Hernandez, M. Hoffmann	Impact of Strawberry Daughter Plant Size on Subsequent Rooting and Plant Development
North Carolina State University Raleigh, NC, USA	A. Wrenn, J. Johnston, B. Jackson, M. Hoffmann	Evaluation of Cultivar Performance and Soilless Substrates in Strawberry Greenhouse Production in Eastern North Carolina
Arizona State University Tempe, AZ, USA	J. Ries, Y. Park	Effects of Far-Red Light on Indoor Strawberry Production
Arizona State University Tempe, AZ, USA	Y. Park	Sole-Source Lighting for Indoor Strawberry Production
University of Arkansas Fayetteville, AR, USA	A.L. McWhirt	Impacts of Fall Planting Date and Fall Row Cover Use on Southeastern Strawberry Production
Texas Tech University Lubbock, TX, USA	T. Montague, R. Wallace, D. Rankin, C. French, L. Stein	Influence of Shade Cloth on Growing Environment, Leaf Gas Exchange, and Fruit Production of two Strawberry (Fragaria ×ananassa) Cultivars Grown in Texas
Texas A&M University College Station, TX, USA	R. Wallace, T. Montague, D. Rankin, S. Panta, C. French, L. Stein	Strawberry Variety Response to Fertilizer and Irrigation Levels in Semi-Arid Texas
Hort Americas Bedford, TX, USA	Karla Garcia	Substrates and Irrigation Management in Strawberry
Old Dominion University Norfolk, VA, USA	L. Horth, C. Frederick, A. Jameson	Mind the Pollination Gap: Important Considerations for Indoor Agriculture
ICL Agronomy St Louis, MO, USA	C. Falen, M. Zepeda	Using Controlled Release, Sustained Release and Fertigated Nutrients to Optimize Yield and Quality for Intensive Strawberry Production
Professional Horticultural Consulting Mossel Bay, South Africa	G. Linsey-Noakes	The Challenges and Opportunities of Growing Strawberries Throughout Sub-Saharan Africa
Pest and Disease Management
Cal Poly Strawberry Center San Luis Obispo, CA, USA	S.S. Hewavitharana	New Developments on Verticillium Wilt Management in the Central Coast of California
Cal Poly Strawberry Center San Luis Obispo, CA, USA	J. Alvarado Rojas, S. Zukoff	Assessing UV-C as a Potential Tool for Arthropod Control in California Strawberry
Cal Poly Strawberry Center San Luis Obispo, CA, USA	K.A. Blauer, G. Holmes	Effects of Plastic Mulch Color and Number of Drip Lines on Incidence of Macrophomina Root Rot
Cal Poly Strawberry Center San Luis Obispo, CA, USA	J. Lin, M. Ahmadi, A. Atefi, C. Fink, M. Mendez	Demonstration and Implementation of Cost-Effective UV-C Technology for California Strawberry Pest Management
Cal Poly Strawberry Center San Luis Obispo, CA, USA	K. Jensen, S. Zukoff	Resistance Status of Twospotted Spider Mite and Lygus Bugs in California Strawberries
Cal Poly Strawberry Center San Luis Obispo, CA, USA	K.A. Blauer, G.J. Holmes	Multi-Year Summary of Fungicide Efficacy on Botrytis Fruit Rot and Powdery Mildew
Cal Poly Strawberry Center San Luis Obispo, CA, USA	G. Holmes, K. Blauer, S. Simard, B. Serpa	Farm-Scale Evaluation of UV-C for Control of Powdery Mildew in Strawberries
Cal Poly Strawberry Center San Luis Obispo, CA, USA	M. Steele, M. Mendez, S. Hewavitharana, G. Holmes	Survey of Soilborne Pathogens of Strawberry in Santa Maria, California
University of California Agriculture and Natural Resources Watsonville, CA, USA	M. Bolda	The Role of SWD and Leak Rot Management in Late Season Fruit Quality
University of California Agriculture and Natural Resources Watsonville, CA, USA	Y.C. Wang, S.S. Hewavitharana, G.J. Holmes	California Survey of Botrytis Fruit Rot Levels in Commercial Strawberry Fields With and Without Fungicide Applications in 2021 and 2022
University of California Davis Davis, CA, USA	C.J. Dilla-Ermita, P. Goldman, J. Jaime, G. Ramos, P.M. Henry	Sporodochia Formed by Fusarium oxysporum f. sp. fragariae: Occurrence and Implications
University of California Davis Davis, CA, USA	K. Elfar, O. Daugovish, A.M. Pastrana, A. Eskalen	Strawberry Cultivar Responses to Fusarium oxysporum f. sp. fragariae Density in Soil
California Strawberry Commission Watsonville, CA, USA	A. Atefi, M. Ahmadi, J. Lin	Lygus Bug Detection Using Machine Learning for Pest Management
California Strawberry Commission Watsonville, CA, USA	A. Atefi, M. Ahmadi, J. Lin	An IOT-Based Operator Aid System for the Lygus Bug Vacuum
California Strawberry Commission Watsonville, CA, USA	C. Fink, M.Mendez, J. Rodriguez, C. Lobo, A. Molinar, J. Lin	Recommended Spray Rig Designs for California Strawberries
California Strawberry Commission Watsonville, CA, USA	O. Daugovish, M. Valdez-Berriz, J. Muramoto, M. Zavatta, P. Henry	Alternative Carbon Sources for Anaerobic Soil Disinfestation in California Strawberry
California Strawberry Commission Watsonville, CA, USA	W. Kraemer, J. Lin, J. Wells, C. Fink	Optimized Lygus Bug Vacuum
California Strawberry Commission Watsonville, CA, USA	J. Rodriguez, M. Mendez, C. Lobo Marin, A. Molinar	Monitoring Pests in California Strawberry Fields
United States Dept. of Agriculture Salinas, CA, USA	P. Henry	Genomic Diversity in Fusarium oxysporum f. sp. fragariae; Implications for Effective Development of Host Resistance
ProFarm Group Davis, CA, USA	T. Hoover	How to Optimize Biological Pesticides in California Strawberry Production
University of Florida Wimauma, FL, USA	M.V. Marin	Leaf Spots of Strawberry Caused by a Novel Species of Pseudomonas
University of Florida Wimauma, FL, USA	N. Peres	Best Management Practices for Nursery Production Including Plugs – Identifying Pathogen Threats
North Carolina State University Raleigh, NC, USA	E. Volk, G. Fox, S.F. Fennimore, J. Neal, M. Hoffmann	Weed and Pathogen Control Through Soil-Applied Steam in Combination with Calcium Oxide and Sodium Peroxide
Summit Agro USA Durham, NC, USA	E. Tedford	Blending Conventional and Bio-Fungicides into Spray Programs for Disease Control, Reduced Residues, and Resistance Management
Virginia Tech University Virginia Beach, VA, USA	A. Smart, S. Shea, P. Richardson, B. Aljawasim, J. Samtani, M. Rahman	Tracing Latent Colletotrichum spp. Infections on Strawberry from Runner Tips to Fruiting Fields
University of Arkansas Fayetteville, AR, USA	A.J. Cato, A. McWhirt, A. Rojas	Impact of a Soil-Applied Thyme Oil Containing Fungicide on Strawberry Yield and Disease Abundance
University of Georgia Athens, GA, USA	D.S. Curry, P.M. Brannen	Fumigation Practices to Eliminate Neopestalotiopsis spp. from Strawberry Fields in Georgia
United States Dept. of Agriculture Beltsville, MD, USA	B. Waldo	Nematode Resistance in Strawberry Germplasm – Upcoming USDA Research
United States Dept. of Agriculture Corvallis, OR, USA	D. Mollov	Strawberry Virus Update
Edge Bioworks Victor, New York, USA	E. Blanco Rodriguez, E. Vafaie	Field scale application program of Rootshield Plus in combination with On-Gard 5-0-0 for the prevention of soilborne diseases in organic strawberries
University of Guelph Guelph, ON, Canada	E. Pate	Effects of Steam Treatment on Cyclamen Mite (Phytonemus Pallidus) and Strawberry Plant Survival
Australia Dept. of Ag. and Fisheries Nambour, Queensland, Australia	A.O. Gomez, J. Gillespie, M. Paynter, J. Neal, L. Rodriguez Coy, D. Garcia Ceron, S. Mattner, A. Gendall, N. Manzie, D. Gardiner	DAF Research on Managing Strawberry Diseases in Australia

The 2023 NASS genetics presentations exemplified the strong track record of strawberry genetics research at UC Davis and the University of Florida. Recent publications from these universities have described novel genetic tools to improve fruit flavor (Fan et al., 2022), Phytophthora crown rot resistance (Jiménez et al., 2022), and Fusarium wilt resistance (Pincot et al., 2022). The two groups have also reported progress toward developing comprehensive molecular breeding tools (Whitaker et al., 2020), understanding the genomic origins of the octoploid strawberry (Hardigan et al., 2021), and characterizing the molecular biology of powdery mildew resistance (Tapia et al., 2021). These new advances will improve breeding efficiency in the primary strawberry production centers of California and Florida, and will also benefit breeding programs in other regions.

While high quality genetics research is critical for successful breeding, members of industry at the NASS are primarily interested in cultivars. New short-day and day-neutral cultivars were introduced in 2023 by breeding programs in Florida, California, Canada, and Italy. A full list of recently named cultivars is available in the Register of Fruit and Nut Cultivars 51, including “Florida Medallion®” and “Florida Pearl®” from the University of Florida, “UDC Finn” and “UDC Mojo” from UC Davis, “AAC Dynamik” from Agriculture and Agri-Food Canada, and “Xante®” from the Consorzio Italiano Vivaisti (see Amyotte et al., 2022).

Production & Propagation

Production and propagation are another core area of focus for NASS. In 2023, presentations were made by university and private research groups in California, as well as several other American university research teams (Figure 1, Table 1). The plant physiologists and production experts described methods to optimize yield by managing nursery plant treatments, planting dates, flower and runner removals, nutrition programs, substrates, mulches, and covers. The scope of production environments ranged from open fields, to covered rows, tunnels, greenhouses, and fully indoor settings. The artificial intelligence and automation teams from the California Strawberry Commission demonstrated new innovations in runner detection, spray rig design, and hoop house automation, while the California company Advanced Farm (https://advanced.farm) showcased recent advances in robotic harvesting. There were also international presentations describing production systems and industry trends in Pakistan and Sub-Saharan Africa (Table 1).

The current production challenges for US growers were recently reviewed by Samtani et al. (2019), who highlighted the need for strategies and technologies to improve climate readiness, pesticide reduction, labor saving, and land optimization. Novel research in these areas by NASS presenters has included the development of a decision support model to predict strawberry growth, development, and fruit production based on weather parameters (Hopf et al., 2022a, 2022b), as well as a model to increase spray coverage based on tractor speed and nozzle setting optimization (Fink et al., 2020). In addition, recent propagation studies have shown the benefits of providing shade treatments for nursery plants (Bostan and Sajid, 2020), decreasing the ratio of nitrate to ammonium (Shi et al., 2021a), and reducing the frequency of stolon removal (Shi et al., 2021b).

The implementation of new production models and propagation strategies could help to improve plant and fruit yield, quality, and labor efficiency for growers in the USA and elsewhere. However, the practical value will likely vary between production systems and environments (Samtani et al., 2019). Alternatively, advances in lighting regimes and other technologies for greenhouses and protected culture systems (e.g., Pramanick and Kashyap, 2019; Runkle et al., 2022) provide a mechanism to address climate uncertainty and soil health challenges by avoiding traditional growing environments altogether. New innovations in this transformative area will likely drive strawberry production research throughout the remainder of the 21st century.

Pest & Disease Management

The final core area of focus for NASS is pest and disease management. In 2023, federal, university, and private research groups in California made presentations under this category (Table 1). There was also strong representation from the University of Florida, North Carolina State University, and Virginia Tech University, among others (Figure 1). The entomology experts discussed new management strategies for endemic pests such as Lygus Bug, Spotted Wing Drosophila, and Cyclamen Mite. Experimental control methods including UV-C, pest vacuuming, and steam treatments were presented. The plant pathology experts discussed the status and severity of several foliar and root fungal pathogens, and presented experimental control methods using fungicides, alternative chemicals, UV-C, steam treatments, and soil disinfestation. To supplement the North American research, Dr. Apollo Gomez from the Australia Department of Agriculture and Fisheries presented an overview of the current pathology challenges, strategies, and innovations in Australia (Table 1).

The conference presentations followed several recent advances in plant pathology published by NASS presenters. A survey of the Watsonville-Salinas region found that Macrophomina, Fusarium, Verticillium, and Phytophthora pathotypes were prevalent across grower fields with no differences between production systems (Steele et al., 2022). Along with these endemic organisms, the new pathogen Aspergillus tubingensis was reported in California (Palmer et al., 2019). Two distinct pathotypes of Fusarium oxysporum f. sp. fragariae were also characterized by USDA researchers in California (Jenner and Henry, 2022). Progress in the identification and control of another novel pathogen, Neopestalotiopsis, was published by the University of Florida (Baggio et al., 2022; Kaur et al., 2022).

The prevalence and diversity of fungal pathogens across strawberry production systems and environments presents an ongoing challenge to growers (reviewed by Daugovish et al., 2021). Alternative control methods such as the use of bacterial endophytes have shown early potential based on laboratory experiments (Mei et al., 2021). Progress toward developing disease resistant strawberry cultivars has also been reported (e.g., Lewers and Enns, 2022; Whitaker et al., 2023). Recent findings from the University of California and the Cal Poly Strawberry Center suggest that the plant and soil microbiome may play a role in different levels of fungal disease between cultivars (Lazcano et al., 2021).

In parallel with the progress in disease management, NASS presenters have reported a number of recent advances in entomology research. In 2020, the Cal Poly entomology and engineering teams reported successful trials of a “bug vacuum” used to remove Lygus Bug from productive fields (Wells et al., 2020). This technology was developed to supplement existing control measures including weed removal, biocontrol parasitoids, and chemical insecticides (Zalom et al., 2018). The need for alternatives to chemical control extends to all strawberry crop pests, due to the risk of developed resistance (Shearer, 2019). A recent industry report for the California Strawberry Commission suggested that the bug vacuum could also be useful against Spotted Wing Drosophila (Zukoff and Mendoza, 2020). As well, research from Ontario suggested that targeted deployment of biocontrols or spot sprays could help to control Cyclamen Mite, since it does not spread substantially within fields (Renkema et al., 2022).

The research topics and recent reports from pathology and entomology teams of the NASS demonstrate that pest and disease management approaches must be specific to the growing environment, production system, and target species. Coordinated research across locations and disciplines can enable the development of precision management strategies with widespread benefits to growers (e.g. Ludwick et al., 2020). Collaborative studies in pest and disease identification, characterization, monitoring, and control are therefore expected to remain a major theme for NASS research in the decades to come.

Future Directions

The oral and poster presentations shared at the 2023 NASS provided a snapshot of the current status and potential path ahead for strawberry research. Dr. Kim Lewers from the USDA Agricultural Research Services presented a summary of the current and proposed investment in strawberry research, offering a glimpse of future priorities for the US government (Table 1). Following the conference, the articles published by NASS participants in the IJFS Special Article Collection will provide additional insight into the status and prospects for incremental and transformative strawberry science in the late 2020s.

The core research areas of pest and disease management, production, and genetics are likely to remain of principal focus as they offer incremental and direct value to growers and stakeholders. For example, Dr. Steven Knapp of UC Davis and Dr. Mark Hoffmann of North Carolina State University outlined two large-scale collaborative Specialty Crops Research Initiative grants in strawberry genomics and clean plant propagation, respectively (Table 1). Based on publications from the 2010s and conference topics in 2023, we predict a continued trend toward research targeting climate change, pesticide reduction, and automation. We also predict increased collaboration across public sector institutions in the USA, such as those exemplified by the University of California and the University of Florida.

We anticipate that certain institutions may further specialize to form centers of excellence in particular niches. Two strong current examples are the propagation team at North Carolina State University and the indoor production team at Arizona State University. Lastly, we expect that the foundational research performed by governments and universities will drive rapid progress in the private sector toward grower-friendly prediction models and robotics technologies, as well as increased production in emerging regions such as Pakistan and Sub-Saharan Africa. Continued investment in research from local to national governments, and engagement from regional to international stakeholders, is required to support all of these advances.

Summary

The North American Strawberry Symposium (NASS) is an international forum for the exchange of new ideas, concepts, and innovations in applied strawberry research. The 2023 conference held in San Luis Obispo, California, covered a breadth of new findings in the areas of breeding, production, and pest management from university, government, and private research teams in the USA and around the world. Climate change was a major cross-cutting theme, and there was a specific focus on production automation and alternative pest management. These themes will be addressed in the 2023 NASS Special Article Collection, and will likely be the subject of ongoing collaborative research throughout the 2020s and beyond.

Submission Description

This editorial review is submitted for the International Journal of Fruit Science, Special Article Collection: 2023 North American Strawberry Symposium.

It is a summary of the research to be presented at the symposium. The purpose is to provide an introduction for the special article collection.

The authors B. Amyotte and J. Samtani are associate editors for the International Journal of Fruit Science, and are the editors of the special article collection.

Acknowledgments

We acknowledge the North American Strawberry Growers Association (NASGA) for organizing the 2023 North American Strawberry Symposium (NASS). In particular, we thank Dr. Kim Lewers, Program Chair and Mr. Kevin Schooley, Executive Director, for their recruitment and coordination efforts. Thank you also to Alam Faraz, Amy Southall, and Jason Wilde of Taylor & Francis for facilitating the creation of this Special Article Collection. We also thank the presenting authors who submitted manuscripts for consideration.

Disclosure statement

B. Amyotte and J. Samtani are members of the 2023 NASS Conference Committee, and are the associate editors of the International Journal of Fruit Science (IJFS). Both B.A. and J.S. participated in developing the scientific program for the conference and invited presenting authors to submit their research to IJFS. All manuscripts submitted to the Special Article Collection will be subjected to full peer-review according to journal standards.