Source: MICHIGAN STATE UNIV submitted to NRP
OPTIMIZING BLUEBERRY POLLINATION TO ENSURE FUTURE YIELDS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1023571
Grant No.
2020-51181-32155
Cumulative Award Amt.
$2,106,866.00
Proposal No.
2020-02627
Multistate No.
(N/A)
Project Start Date
Sep 1, 2020
Project End Date
Aug 31, 2025
Grant Year
2020
Program Code
[SCRI]- Specialty Crop Research Initiative
Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824
Performing Department
ENTOMOLOGY
Non Technical Summary
Blueberry is a significant specialty crop grown across the United States that supports healthy human diets and farm communities, including growers and beekeepers. Pollination is a critical component of successful and profitable blueberry production, and although there have been major advances in breeding, horticultural practices, and pest management for this crop, extension recommendations for pollination have not changed in decades. Spring weather variability challenges growers' ability to appropriately adjust their bee stocking, and there is little research-based guidance on how to adapt pollination strategies for specific cultivars, weather conditions, or farm situations. This project will respond to stakeholder priorities to provide modern pollination-related decision support tools and recommendations, by combining expertise from applied entomology, apiculture, horticulture, breeding, economics, and meterology disciplines working with growers across four key blueberry-producing states. Our team will develop new research and extension outputs that enable growers to tailor their pollination practices for greater return on investment. Specifically, we will compare and conduct cost-benefit analyses of different strategies for honey bee pollination; determine pollination requirements and pollinator attraction across new and existing cultivars; determine how variable weather conditions affect blueberry pollination; develop predictive models of pollination, fruit set, and yield for development of a Pollination Planner; and deliver information on improved blueberry pollination to the industry.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21111201130100%
Knowledge Area
211 - Insects, Mites, and Other Arthropods Affecting Plants;

Subject Of Investigation
1120 - Blueberry;

Field Of Science
1130 - Entomology and acarology;
Goals / Objectives
1. Conduct cost-benefit analyses of different honey bee stocking density and placement strategies to develop recommendations for modern blueberry systems.2. Determine pollination requirements and pollinator attraction across new and existing cultivars.3. Determine how variable weather conditions affect blueberry pollination.4. Develop predictive models of pollination, fruit set, and yield for creation of a Pollination Planner to improve pollination management decisions.5. Deliver information on improved blueberry pollination to the industry.
Project Methods
1a. Comparing stocking density. We will compare yields of commercial blueberry cultivars between existing standard colony densities (two colonies/acre in MI and three colonies/acre in FL) and double the density currently used(4 colonies/acre in MI and 6 colonies/acre in FL).Using six replicated ~40 acre farms for each stocking level in MI and FL, we will measure bee activity on flowers and overall fruit set using the methods described below to determine whether increased honey bee stocking densities results in increased yields.During two-three weeks of peak bloom for each cultivar, when it is sunny, air temperature exceeds 60oF, and wind speed is below 5 mph (Clark & Robert 2018), we will record the number of bees visiting blueberry flowers at the farms with high and low stocking densities.1b. Comparing colony placement. In each cooperating state, we will monitor crop pollination and honey bee colony health in fields with colonies placed in larger clusters away from production areas to reduce pesticide exposure and improve placement efficiency, compared to placement throughout the production area (the current standard).1c. Economic analysis. For the baseline scenario of the economic analysis, we will utilize the enterprise budgets generated for blueberry production in WA, OR,FL,and MI. The baseline scenario will have the existing standard colony density for blueberry production in the three regions (4 states). We will estimate the costs and benefits of the alternative practices (i.e., increasing honey bee hive stocking densities and hive placmenet) and compare these figures with the baseline using partial budget analysis.Using results of the partial budget analysis, we will calculate and compare break-even points for the baseline and alternative scenarios.The break-even point will serve as the threshold after which an economic loss occurs. In addition, we will undertake risk analysis by examining the sensitivity of profit uncertainty in critical economic parameters (e.g., crop yield, output price, pollination cost). We will also use the information gathered in this objective to determine how many pounds of blueberries each honey bee colony supports, resulting in a metric that can be compared among cultivars and regions.Objective 2. Five leading cultivars and five promising new cultivars were selected from each growing region, representing a large variation in genotypes used in current breeding programs (Table 1). Cultivars were selected with input from experts in highbush blueberry breeding.These cultivars will be tested to determine their inherent needs for pollination and their response to pollination treatments in the greenhouse and field.2a. Comparing pollination requirements among cultivars. To determine the level of auto-fertility and self-compatibility of these cultivars, 5 plants of each cultivar will be grown under optimal conditions in a greenhouse. During the flowering period, three flower clusters on each plant will be assigned to one of the following treatments: 1) no pollination, 2) self-pollination, and 3) cross-pollination. Pollination will be achieved using a fine paint brush to apply pollen collected from the same cultivar (self-pollination) or from a different cultivar with distinct parentage that blooms at the same time (cross-pollination).2b. Determine how flower traits vary among cultivars, and implications for pollination. Using the same cultivars we evaluate in the field as described above, we will additionally measure the physical and chemical traits of flowers. Bee visitation rates will be measured for each cultivar at each site, using timed observations conducted on three separate dates during the bloom period for each cultivar.Objective 3.We will complete three sub-objectives: 1) Determine bloom phenology based on accumulation of growing degree units (e.g., days); 2) Understand how environmental conditions influence honey bee activity across the important production regions included in this study; and 3) Determine how a range of temperature and humidity conditions affect blueberry pollination. Field, growth chamber, and lab work will be done in 2021 and2022, with resultant data being used for constructing and validating the Pollination Planner tool in 2023-2024.Objective 4. Develop predictive models of pollination, fruit set, and yield for creation of a Pollination Planner to improve pollination management decisions. We will coordinate the information gathered in Objectives 1-3 to develop and validate regionally-relevant and cultivar sensitive models for blueberry pollination, fruit set, and yields, which will then drive our Pollination Planner. This will be based on user-inputs on cultivar, stocking density, price per colony, and price per pound. The system will use the data gathered in this project and in previous research to include how relative pollination and yield is impacted by regional weather variables across cultivars. The tool will also show how relative profit levels vary based on stocking density and berry prices, further supporting pollination decisions.5. Deliver information on improved blueberry pollination to the industry. We propose toconnect and engage blueberry grower, beekeeper, and crop consultant networks by: 1) includingadvisory board members, innovative growers, beekeepers,and crop consultantsintheinitial stages of developing the Pollination Planner;2) building a broader network of growers, beekeepers, and crop consultants through the frequent release of multimedia (video, podcast, infographic) content through social media networksand online resources (e.g., project website and Pollination Planner tool); 3) surveying our network to determine current practices and understanding around blueberry pollination and how these change as a result of our project; and 4) hands-on field day workshop and training activities combined with printed Extension products to support growers and crop consultants in their use of the Pollination Planner. The surveys will be conducted at the start and the end of the project to provide Impact Assessment, and this will be led by co-PD Suzette Galanito, who has experience developing surveys for fruit growers, gaining Institutional Review Board approval, etc. (see Obj. 5b). This project we will create a range of Extension and outreach products to extend the information beyond the project team and the cooperating states. This information will be delivered to growers, beekeepers, and Extension professionals through workshops, existing university websites (MSU pollination site, MSU Blueberry Team, UF Blueberry Extension, Oregon Bee Project/OSU Pollinator Extension, WSU Small Fruits), and our regional Extension networks. Our materials will also be highlighted in the Small Fruit Update a newsletter that is based in the PNW but whose reach extends across the nation. This highly professional and timely newsletter is read by hundreds of growers and other industry professionals each time it is released by email. Additionally, the team in Oregon on this project are subcontracting the on-farm activities in that state to a field research team that work closely with the Small Fruit Update group, helping to ensure a close connection between the research and education.?

Progress 09/01/23 to 08/31/24

Outputs
Target Audience:This project has developed new information about blueberry pollination for delivery to a wide range of decision-makers interfacing with blueberry producers. This includes growers, extension educators, crop consultants, other research students, postdocs, and faculty in the agricultural sciences. Changes/Problems:With students graduating and postdocs moving to new positions, the team is adjusting our publication plans to ensure the research studies are published by the end of the No Cost Extension period. What opportunities for training and professional development has the project provided?The project has provided training for multiple trainees on pollination data collection, honey bee handling, and data analysis.Two MS graduate students (Lauren Goldstein and Kayal Brouwer) and one PhD student (Jenna Walters) completed their graduate research through this project. In addition, one PhD student (Salena Helmreich) has supported outreach and has been engaged in supporting the project goals. Co-PI DeVetter also presented on blueberry pollination and project findings in her 3-credit pomology class in fall 2023 (n=33 students), and Dr. Isaacs included information from this project in a graduate-level class on pollinator management (n=12 students). How have the results been disseminated to communities of interest?The project information has been distributed through the active extension programs of project participants. The list below provides examples of talks provided by project participants in the last year of the project. Isaacs, R. (2024) Understanding how bloom conditions influence blueberry pollination. Oregon Blueberry Conference, Salem, Oregon. February 6, 2024.300 growers. Isaacs, R. (2024) Extreme heat and blueberry pollination. Lower Mainland Horticultural Conference. Abbortsford, BC, Canada. March 6, 2024. 150 blueberry growers (presented online). Brouwer, K. 2023. Impact of colony placement on pollination. Lynden Ag Show. Lynden, WA. DeVetter, L.W. et al. 2024. Honey Bee Hive Placement affects on Pesticide Exposure ?and Pollination Services in Highbush Blueberry Systems. Scandinavian Association for Pollination Ecology. Walloon, Belgium. DeVetter, L.W. et al. 2024. Buzzworthy Insights: Maximizing Blueberry Pollination. Lower Mainland Horticulture Improvement Association Grower Short Course. Abbotsford, British Columbia, Canada. DeVetter, L.W. et al. 2024. Pollination Insights - Optimizing Honey Bee Mediated Pollination in Highbush Blueberry?. International Society for Horticultural Science Vaccinium Symposium. Charlottetown, Prince Edward Island, Canada. DeVetter, LW. et al. 2024. Buzzworthy Insights: Maximizing Blueberry Pollination. Skagit Valley Beekeepers Association. Sedro Wolley, WA. DeVetter, L.W., S. Helmreich, and A. Melathopoulos. 2024. Buzzworthy Insights. Updates on Blueberry Pollination Research. Oregon State University Field Day. Aurora, OR. What do you plan to do during the next reporting period to accomplish the goals?The project team will complete final data analyses and share information through peer-reviewed manuscripts, presentations at grower and beekeeper events, and through our project website.

Impacts
What was accomplished under these goals? 1. Conduct cost-benefit analyses of different honey bee stocking density and placement strategies to develop recommendations for modern blueberry systems. Research on honey bee placement effects on pollination is complete and published. Pesticide residue work is ongoing with some new, expanded projects planned contingent upon funding. Analysis ofstocking density and colony strength is ongoing and being integrated with cost-benefit analyses, with two publications planned for 2025. 2. Determine pollination requirements and pollinator attraction across new and existing cultivars.Greenhouse and field studies have been conducted to compare performance of different cultivars and how that varies based on the source of pollen, whether self or cross pollen. This information is being used to help develop recommendations for planting designs in northern highbush and southern highbush cultivars. Field studies have been conducted to compare cultivars for their relative attraction of bees, although relatively low bee activity made it challenging to make strong conclusions. 3. Determine how variable weather conditions affect blueberry pollination.Studies in Michigan and Florida have been completed to compare blueberry performance when blooms are exposed to extreme heat or different levels of humidity. We have found that extreme heat denatures pollen performance through disrupting the nutritional quality, resulting in poor germination and pollen tube growth that results in low fruit set. The threshold for this damage was found to be above 90 degrees Fahrenheit, and so growers are using this threshold to initiate field cooling using overhead sprinklers. We also found that pollen release progresses as air humidity declines and pollen dries out, and we also found that the pollen does not release when humidity is high. These insights can help with predictions for when pollination is expected to be most effective during the period of blueberry bloom. 4. Develop predictive models of pollination, fruit set, and yield for creation of a Pollination Planner to improve pollination management decisions.A beta-version of the bloom phenology model was uploaded to Michigan State University and Washington State University Enviroweather platforms and it has been beta-tested by stakeholders. Stakeholder feedback was obtained, and model refinement based on feedback is underway. The honey bee stocking density app is nearing completion. Both models will be presented and distributed during winter and spring grower conferences. 5. Deliver information on improved blueberry pollination to the industry.Information has been shared with local, regional, national, and international grower, beekeeper, consulting, and academic audiences through annual presentations, manuscripts, and proceeding articles. A complete grower guide titled, "Blossoming Success: Best Practices for Northern Highbush Blueberry Pollination", is nearing completion and syntheses project findings with other literature on pollination. A similar guide published by the University of Florida is also being updated to reflect new insights from the project. Information will be made available through our project website and further disseminated via local and regional email listservs complemented with social media.Our team has also developed two new podcast episodes not reported previously. Our www.blueberrypollination.org website is established, and our X social media account has 274 followers, plus our YouTube video on grading colonies has had 214 views.

Publications

  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Brouwer, K., M. Eeraerts, E. Rogers, L. Goldstein, J.A. Perkins, M.O. Milbrath, A. Melathopoulos, J. Meyer, C. Kogan, R. Isaacs, and L.W. DeVetter. 2024. Strategic honey bee hive placement improves honey bee visitation but not pollination in northern highbush blueberry. Journal of Economic Entomology. toae267
  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Chabert, S., M. Eeraerts, L.W. DeVetter, M. Borghi, and R. Mallinger. 2024. Intraspecific crop diversity for enhanced pollination success, insect pollinator populations, and yield outcomes: need, benefits, and implementation. A review. Agronomy for Sustainable Development. 44(50).
  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Eeraerts, M., S. Chabert, L.W. DeVetter, P. Bat�ry, J. Ternest, K. Verheyen, K. Bobiwash, K. Brouwer, D. Garcia, A. de Groot, J. Gibbs, L. Goldstein, D. Kleijn, A. Melathopoulos, S.Z. Miller, M. Mi�arro, A. Montero-Casta�o, C. Nicholson, J.A. Perkins, N. Raine, S. Rao, J. Reilly, T. Ricketts, E. Rogers, and R. Isaacs. 2024. Pollination deficits and their relation with insect pollinator visitation are cultivar-dependent in an entomophilous crop. Agriculture, Ecosystems and Environment. 369:109036.
  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Eeraerts, M., L.W. DeVetter, P�ter Bat�ry, J.J. Ternest, R. Mallinger, J. Campbell, P. Cavigliasso, A. De Groot, B. Faye, J. Gibbs, D. Kleijn, A. Montero-Casta�o, A. Melathopoulos, C. Nicholson, N. Raine, T. Ricketts, and R. Isaacs. 2023. Global synthesis on highbush blueberry pollination reveal considerable pollinator contributions of both honey bees and wild bees by region. Journal of Applied Ecology. 60(12):2528-2539. https://doi.org/10.1111/1365-2664.14516
  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Walters, J., Barlass, M., Fisher, R., and Isaacs, R. (2024) Extreme heat exposure of host plants indirectly reduces solitary bee fecundity and survival. Proc. R. Soc. B.29120240714


Progress 09/01/22 to 08/31/23

Outputs
Target Audience:This project's resultsand outcomes will be delivered to blueberry growers, bee keepers, extension educators, consultants, and others that help with decision-making on blueberry farms Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has supported the trainign of one postdoctoral researcher, three graduate students, and 10 undergraduate students as part of their research experience. How have the results been disseminated to communities of interest?Results from this project have been shared with the blueberry industry through various discussions, meetings, and publications either formally or informally. This list provides the formal contacts where we have connected with growers and beekeepers. Presentations Taking the guesswork out of pollination: the blueberry pollination planner. Salem, OR, February 2, 2023, 300 contacts Impact of honey bee hive placement and stocking density on blueberry pollination, CranberrySummer Field Day, Long Beach, WA, July 19, 2023, 30 contacts Improving blueberry pollination, Dort College EcoAg Student Tour, July 15, 2023, Mount Vernon, WA, 15 contacts Updates on blueberry pollination research, Western Washington Berry Workshop, March 10, 2023, Mount Vernon, WA, 30 contacts Maximizing pollination in blueberry, Wilbur Ellis Blueberry Webinar, January 31, 2023, online, 80 contacts Impact of honey bee hive placement and stocking density on blueberry pollination, January, 28, 2023, Abbotsford, Canada, 200 contacts Impacts of honey bee hive placement on blueberry pollination, Washington Small Fruit Conference, November 29, 2022, Lynden, WA, 130 contacts Landscape- or field-level honey bee hive densities in highbush blueberry - which is better? NABREW Conference, June 27-29, 2022, Online, 70 contacts Stocking density and placement in blueberry farms - research update. July 21, 2023. Michigan Commercial Beekeepers Association. MSU Pollinator Performance Center. East Lansing, MI. 30 contacts (beekeepers). Extreme heat effects on blueberry pollination and management to limit damage. July 21, 2023. Michigan Commercial Beekeepers Association. MSU Pollinator Performance Center. East Lansing, MI. 30 contacts (beekeepers). Extreme heat effects on blueberry pollination and management to limit damage. June 13, 2023. Pollination hands-on workshop. First Pick Farms, West Olive, MI. 25 contacts (growers). Stocking density and placement in blueberry farms - research update. June 13, 2023. Pollination hands-on workshop. Cornerstone Ag., Grand Junction, MI. 19 contacts (growers). Extreme heat effects on blueberry pollination and management to limit damage. June 5, 2023. Pollination hands-on workshop. First Pick Farms, West Olive, MI. 25 contacts (growers). Stocking density and placement in blueberry farms - research update. June 5, 2023. Pollination hands-on workshop. First Pick Farms, West Olive, MI. 25 contacts (growers). Optimizing blueberry pollination to ensure future yields. SCRI Program virtual PD meeting. March 9, 2023. Online webinar, 110 contacts (agricultural scientists and agency staff). Field Days Updates on the Pollination Planner, July 26, 2023, Oregon State University Blueberry Field Day, Aurora, OR. 95 contacts What's buzzing? Blueberry pollination research update, Bees, Bots, and Blueberries in the BerrySmart Blueberry Fields, May 30, 2023, Burlington, WA, 40 contacts Pollination research update. MSU blueberry research day. August 25, 2022. Trevor Nichols Research Center, Fennville, MI. 40 contacts (growers). Optimizing pollination inmodern blueberry systems: research updates and directions. October 22, 2022. Florida Blueberry Growers Association Annual Conference. Howie in the Hills, FL 150 contacts (growers). Optimizing pollination inmodern blueberry systems. January 2023. SE Fruit and Vegetable Growers Regional Conference. Savannah, GA 250 contacts (growers). Workshop on blueberry pollination as part of Florida Blueberry Growers AssociationAnnual Field Day. March 2023. Citra, FL 100 contacts (growers). What do you plan to do during the next reporting period to accomplish the goals?Our team will continue to gather input from growersand our advisory board. This winter we have a few team members leaving through graduation and/or contracts ending, so we will be re-evaluate our alignment of team members and objectives with the remaining budget to complete the proposed research. While our main fieldwork is complete, there are some targeted field experiments planned and continued greenhouse research we expect to complete in 2024.

Impacts
What was accomplished under these goals? Objective 1. Conduct cost-benefit analyses of different honey bee stocking density and placement strategies to develop recommendations for modern blueberry systems.Data evaluating the effects of different honey bee stocking densities were collected from multiple field sites in Michigan and Florida. Preliminary analyses of data from Michigan have been completed and included in a graduate student's thesis. Remaining data analyses are underway across the whole project to synthesize how various measurements of honey bee abundance relate to pollination service in highbush blueberry.Field studies assessing the effects of honey bee hive placement on blueberry pollination and pesticide exposure are complete with data collection completed in 2021-2023 in Michigan, Oregon, and Washington. During the visits to these farms, there were opportunities to collect data for building and validating the bloom predictor in Objective 3. All results are being shared with our collaborating economist who is conducting cost-benefit analyses of various hive density and placement strategies for incorporationinto our Pollination Planner (Objective 4). Objective 2. Determine pollination requirements and pollinator attraction across new and existing cultivars. We compared the pollination requirements of 11 northern highbush blueberry cultivars by conducting hand pollination experiments. Specifically, we assessed autofertility, self-fertility, and cross pollination with varying single pollen donors and multiple pollen donors. For all pollination treatments, we assessed fruit set and berry weight. We are currently assessing seed set, sugar and acidity, and firmness in all resulting berries. Time to ripen for all berries across all pollination treatments was also calculated. Additionally, we compared variation in floral traits across 10 southern highbush and 9 northern highbush cultivars including nectar volume and nectar sugar content, flower density, and flower morphology. We additionally collected anthers from all cultivars and are in the process of assessing pollen quantity and its variation across cultivars. Our preliminary results show that cross-pollination increased fruit weight per flower significantly by 14-420% depending on the cultivar in 9 of 11 cultivars, with no significant increase in the other 2 cultivars. It also significantly decreased the time to ripen by 4-18 days in 5 cultivars, and it significantly increased the fruit firmness by 6-38% in 7 cultivars. There was also nearly no parthenocarpy for any cultivar. The total amount of nectar secreted per flower varied by 4.6-fold in southern cultivars, from 2.0 ± 0.5 in 'Farthing' to 9.3 ± 1.2 mg of sugar per flower in 'Kestrel', and by 2.1-fold in northern cultivars, from 6.2 ± 1.1 in 'Bluecrop' to 12.8 ± 1.4 mg of sugar per flower in 'Draper'. Northern cultivars secreted more nectar per flower than southern cultivars. Corolla length and aperture diameter also varied greatly among cultivars and between northern and southern cultivars. Flowers of northern cultivars were on average smaller than flowers of southern cultivars, with shorter corollas (ranging from 7.3 to 9.2 mm in northern and from 8.3 to 11.5 mm in southern cultivars) and shorter aperture diameters (from 2.3 to 3.4 mm in northern and from 3.4 to 5.2 mm in southern cultivars). Studies to compare attraction of bees to different cultivars were started in 2023, but low bee abundance, scale of the experiment, and weather conditions all contributed to low bee activity in the trial. Revised plans will be developed with our advisory board's input this winter. Objective 3. Determine how variable weather conditions affect blueberry pollination. Repeated counting of opening blueberry flowers was done on bushes of various cultivars in multiple farms and across the states within this project. This information is being used to construct degree-day based models of bloom phenology that can be integrated into local weather networks to provide updates to growers on bloom timing and when bee delivery should be planned. This can also guide changes in pest management activities once bloom ends and honey bee hives are removed from the fields. Data on bee activity and environmental conditions has been collected across two field seasons in all four states. Those data are being collated for a project-wide analysis of how environmental conditions affect bee foraging activity. The effects of extreme weather conditions have continued to be evaluated in laboratory and some field studies. Blueberry pollen was collected from various southern highbush blueberry cultivars and germination and pollen tube growth of the pollen were measured across a range of temperature conditions from 10 to 37.5 oC (50 to 99.5 oF). Results from this study show similar results to the recent Walters & Isaacs (2023) study in terms of the response to different conditions. Extreme high temperatures inhibited pollen development in a similar way to the earlier research, but we also found that on average the southern highbush cultivars were better able to develop at 10 oC compared with the northern cultivars. Overhead irrigation was tested at a research planting to determine the degree of cooling provided. intermittent irrigation during the hottest parts of the day reduced the air temperature by 5-10 oF. To determine the effect of humidity on pollen production, pollen production was compared in 'Emerald' when the conditions were 45 or 85% relative humidity. Pollen was mostly released during the first day after flower opening when the growth chamber was set at 45% RH. At 85% RH, pollen was never released, indicating that high humidity conditions are not conducive for pollen release. This may be a mechanism for flowers to hold pollen until bee activity is more likely, and a follow-up experiment indicated that flowers held at 85% RH will release pollen once the flowers return to lower humidity conditions. Objective 4. Develop predictive models of pollination, fruit set, and yield for creation of a Pollination Planner to improve pollination management decisions.A draft Pollination Planner interface was created and presented to growers and crop consultants in all participating states in a focus-group setting in order to get feedback on optimal interface design and model utility. The draft Pollination Planner included a beta-version of a bloom phenology model that incorporated data from Michigan and Washington. Additionally, the Pollination Planner had a beta-version of models that estimated the effects of changing hive density on blueberry fruit set, berry weight, yield, and profitability. Model refinement is underway and feedback as well as new data will be incorporated into the next generation model circulated for the 2024 growing cycle. ?Objective 5. Deliver information on improved blueberry pollination to the industry. Information from the project was delivered to 1,639 contacts at 15 grower talks and 6 field days in Washington, Michigan, Oregon, Florida and the Canadian province of British Columbia. We also produced a 17 min video for growers to learn to grade colony strength in blueberry fields using hive entrance counts, which has resulted in 122 views. We also produced three podcast episodes highlighting aspects of the project (listed below) resulting in 4,588 downloads. Our website continues to grow in visibility and content with materials from the project being added as they become available. The project was also covered in two trade publications and three scientific publications.

Publications

  • Type: Journal Articles Status: Published Year Published: 2022 Citation: DeVetter LW, S Chabert, MO Milbrath, RE Mallinger, J Walters, R Isaacs, SP Galinato, C Kogan, K Brouwer, A Melathopoulos, and M Eeraerts. 2022. Toward evidence-based decision support systems to optimize pollination and yields in highbush blueberry. Frontiers in Sustainable Food Systems. 6:1006201. https://doi.org/10.3389/fsufs.2022.1006201.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Walters, J. and R. Isaacs. 2023. Pollen germination and tube growth in Northern highbush blueberry are inhibited by extreme heat. HortScience 58, 635-642. https://doi.org/10.21273/HORTSCI17075-23
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Eeraerts, M., E. Rogers, B. Gillespie, L. Best, O.M Smith, and L.W DeVetter. 2023. Landscape-level honey bee hive density, instead of field-level hive density, enhances honey bee visitation in blueberry. Landscape Ecology. 38(2):583-595. https://doi.org/10.1007/s10980-022-01562-1


Progress 09/01/21 to 08/31/22

Outputs
Target Audience:This project is developing information for management of blueberry pollination management that will inform decisions by growers, extensioneducators, and crop consultants Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has provided training for multiple trainees on pollination data collection, honey bee handling, and analysis. How have the results been disseminated to communities of interest?Results have been shared with the Advisory Board. In Washington DeVetter's team did the following presentations: DeVetter, L.W., J. Myer, A. Melathopoulos, and K. Brouwer. 2022. PNW Blueberry Pollination Project Update - Hive assessments and colony placement. Oregon Blueberry Field Day. Aurora, OR. Brouwer, K., E. Rogers, and L.W. DeVetter. 2022. Blueberry Pollination Research in Action. Dordt University Student Field Trip. Mount Vernon, WA. Brouwer, K., E. Rogers, and L.W. DeVetter. 2022. Blueberry Pollination Research in Washington. WSU NWREC Field Day. Mount Vernon, WA. DeVetter, L.W. 2021. Blueberry Pollination Update. Washington Small Fruit Conference. Lynden, WA. DeVetter, L.W. 2021. Blueberry Pollination Research Update. Washington Blueberry Commission Research Review. Mount Vernon, WA. What do you plan to do during the next reporting period to accomplish the goals?Second-year data from Florida will be collected for the hive density experiment and associated cost/benefit analysis will be completed. We also plan to estimate the income effects using data from a yield model developed in Objective 4. We plan to repeat Obj. 1a across ~8 farms in Florida. We will also collect data relevant for Obj.3 including weather and bee foraging rates on these same farms, and potentially bloom phenology and weather for degree-day models. We will conduct pollination experiments on northern highbush cultivars for Obj. 2 and additionally conduct an experiment for Obj. 2 designed to assess the relative attractiveness of different blueberry cultivars and the floral traits that determine attraction. Pesticide exposure data collection will also be finalized, and all project data will continue to be analyzed based on advisory board feedback and prepared for publications and dissemination to industry stakeholders. Additionally, data will be shared with the Objective 4 team for the Pollination Planner. For Objective 5, we will publish the survey results as extension bulletin, and conduct exit surveys as well as an endline survey to assess the contributions of the project, including changes in practices or knowledge of stakeholders. We also plan to produce videos associated with the Hive Planner, two additional podcast episodes, and grower engagement on using the Pollination Planner. Results from this project will also be shared with the Michigan Commercial Beekeepers Association at their meeting in July 2023.

Impacts
What was accomplished under these goals? Objective 1. Conduct cost-benefit analyses of different honey bee stocking density and placement strategies to develop recommendations for modern blueberry systems. Field experiments were successfully completed for a second year on commercial blueberry farms for the honey bee colony density study (in Michigan only; Florida will be repeated in 2023) and colony placement study (in Michigan, Washington, and Oregon). Pollinators and pollination success have been surveyed, and pesticide exposure data have been collected according to established protocols. Preliminary data analysis was initiated and is ongoing at the time of reporting. Furthermore, economic analyses are in progress and additional revenue and break-even yields that are needed to offset the cost of renting additional hive/s in Michigan and Florida have been estimated. Although current data show that hive placement has no income effects for growers, there may be economic implications for beekeepers for certain hive placements, specifically clumping hives for efficiency and placing pallets such that they face away the field to reduce pesticide exposure. Evaluations of honey bee colony cluster sizes, forager activity, and bee abundance on nearby blueberry flowers were done for fields and colonies under different placement regimes. These colonies were also assessed for other health metrics, including presence of diseases. This information is being used to help understand the link between blueberry pollination contracts and colony diseases. Objective 2. Determine pollination requirements and pollinator attraction across new and existing cultivars. We conducted greenhouse experiments to assess the pollination requirements of 10 southern highbush blueberry cultivars. We conducted a variety of pollination treatments and assessed fruit set, berry weight, berry firmness, brix and acid content of berries, time to ripen, and seed set. We have begun data analysis and presented findings to FL Blueberry Growers Association and the advisory board. Finally, we prepared for the 2023 season in which we will conduct similar experiments with northern highbush blueberries and an additional experiment on the relative attractiveness of different cultivars. Objective 3. Determine how variable weather conditions affect blueberry pollination. We continued to analyze data collected in 2021 to determine the effect of weather on honey bee foraging in the field, as well as controlled laboratory experiments examining the effect of temperature on both the effective pollination period of blueberries and nectar secretion rates. We have begun to write a manuscript on the experimental data for a peer-reviewed publication. Additionally, we monitored weather conditions during bloom in Oregon, Michigan, and Washington as part of activities described under Objective 1b. Pollen germination was measured across a range of temperature conditions in northern highbush cultivars, and this will be repeated in 2023 in southern highbush cultivars. Objective 4. Develop predictive models of pollination, fruit set, and yield for creation of a Pollination Planner to improve pollination management decisions. Planning and refinement of the Pollination Planner continued with attention to the interface, method of deployment, and planned user-inputs and model-outputs for short- (i.e., timing of bloom, honey bee activity by weather, and petal fall) and long-term (i.e., stocking density) planner outcomes. Coordination between Objective 3 and 5 teams continued to inform optimal Pollination Planner design and outputs. Preliminary percent bloom and petal fall prediction models were developed for Michigan and Washington by the Objective 3 team and will be part of future beta-testing of the Pollination Planner. ?Objective 5. Deliver information on improved blueberry pollination to the industry. An online survey about current blueberry pollination practices and challenges was disseminated to blueberry growers between May 2021 and April 2022 through grower meetings and conferences and advertisements in trade journals. We received a total of 539 responses, with 487 responses containing useable data. Majority of responses came from Michigan (30%), while 14% of total was from Florida, 16% from Oregon and 8% from Washington. We wrote an article for the Blueberry News, to be published in late fall 2022, on our preliminary findings in Obj. 1a. Results have been presented to grower commissions in Oregon, Washington, and Florida in 2022. We have also conducted a survey of growers in each region to determine how they would use the Pollination Planner. Our team has also developed two podcast episodes: https://extension.oregonstate.edu/podcast/pollination-podcast/225-chabert-would-blueberry-yield-benefit-planting-different-cultivars and https://extension.oregonstate.edu/podcast/pollination-podcast/192-lisa-devetter-blueberry-pollination-planner

Publications

  • Type: Journal Articles Status: Published Year Published: 2022 Citation: DeVetter,LW, Chabert, S, Milbrath, M, Mallinger, R, Walters, J, Isaacs, I, Galinato, S, Kogan, C, Brouwer, K, Melathopoulos, A, Eeraerts, M (2022). Towards evidence-based decision support systems to optimize pollination and yields in highbush blueberry. Frontiers in Sustainable Food Systems: 6:1006201. (IF = 5.01)
  • Type: Other Status: Published Year Published: 2022 Citation: Brouwer, K. and L.W. Brouwer. 2022. Annual Differences in Honey Bee Foraging Conditions in Northwest Washington. Whatcom Ag Monthly. https://extension.wsu.edu/wam/annual-differences-in-honey-bee-foraging-conditions-in-northwest-washington/.


Progress 09/01/20 to 08/31/21

Outputs
Target Audience:This project is developing new information for blueberry growers andtheir advisors. The project is targeting audiences including growers, extension educators, applied researchers, and weather system staff with our information and programs. We are also spreading information about the project more widely through social media. Changes/Problems:Extreme heat in the summer of 2021 in the Pacific Northwest where some of this project is being conducted resulted in effects on yield measures. What opportunities for training and professional development has the project provided?What opportunities for training and professional development has the project provided? In Florida, one post-doctoral researcher, Stan Chabert, and research staff, Shiala Morales Naranjo, have received training and professional development as part of this project. In Washington, the project allowed for postdoc, Maxime Eeraerts, to gain more experience with honey bee pollination and leading a team of undergraduate and graduate researchers during the pollination season. In Michigan, two graduate students, Jenna Walters and Lauren Goldstein, have gained many new research skills and have had their tuition covered and research supported by this project.Additionally, many undergraduatestudents/technicians from the participating universities have received training and professional development, including pollination, experimental design set up, data collection, data management, and creation of grower reports as part of this project. How have the results been disseminated to communities of interest?How have the results been disseminated to communities of interest? In Florida and Washington, allparticipating farmsreceived a grower report with study results from the 2021 seasonand farm-specific information. In Washington, information on honey bee hive assessments, project aims and preliminary findings, and a review of blueberry pollination was shared at two field days: 1) One in Albany, Oregon on July 7 and 2) One in Aurora, OR on July 15 in partnership with co-PI Melathopoulos. DeVetter participated in a PolliNation podcast about the project, which received 927 downloads.Information was also shared via Twitter. DeVetter participated in a PolliNation podcast about the project, which received 927 downloads. Multiple social media posts were shared through the Oregon Bee Project and Andony Melathopoulos was interviewed for two stories with Oregon local media. What do you plan to do during the next reporting period to accomplish the goals?What do you plan to do during the next reporting period to accomplish the goals? For Objective 1, we will repeat the field experiments and we will also optimize the protocol. For Objective 1c, we will finish updating the Washington and Michigan baseline enterprise budgets, collect data related to our alternative scenarios for the cost benefit analysis, and conduct preliminary partial budget analysis.Expand Objective 2, including an evaluation of pollination requirements on additional southern highbush blueberry cultivars along with northern highbush blueberry cultivars. We will repeat pollination treatments on this larger set ofcultivars, andconduct additional experiments to investigate how degree of relatedness influences the benefits of cross pollination for yield and fruit quality. Finally, we will conduct experiments to measure pollinator preferences across cultivars and to link these preferences to specific floral traits.For Objective 3 we will be repeating and expanding experiments on the effects of temperature on nectar secretion and the effective pollination periodacrossdifferent cultivars.We will continue to collect environmental data on crop phenology and honey bee foraging, model those data, and leverage it for the Pollination Planner. For Objective 4, we will continue to work on predictive models for the Pollination Planner and work with the Extension team in Objective 5b on obtaining feedback on our draft Pollination Planner interface from stakeholders and our advisory board.For Objective 5, we will disseminate information at grower conferences, field days, work with Objective 4 team on getting feedback on the Pollination Planner draft interface. Collection of baseline data for the impact assessment will also be finalized.

Impacts
What was accomplished under these goals? 1. Conduct cost-benefit analyses of differenthoney beestocking density and placement strategies to develop recommendations for modern blueberry systems.The Washington team led development of a shared protocol and data templates for sub-objectives 1a-1b with contributions from the entire project team. For subobjective 1a (stocking density), twelvepairedblueberryfarmsacross both Floridaand Michigan were selected (24 total).Half of these farmsreceivedtheaveragehoney bee density treatment, while the other halfreceived either double the average honey beedensitytreatment (in Florida), or an increase of 2 hives per acre than the standard stocking rate (in Michigan). At all farms,honey beevisitation rates were measured on 1or2 cultivars at least 3 times per cultivarduring bloom.Honey beeactivity at the hive (1 min forager counts)was measured on 3-6 occasionsper farm, and cluster counts were performed on a subset of hives at the beginning of the season. Fruit set, weight, and seed set were measured on select branches of 1or2 cultivars per farm, and pollination treatments (open, closed, hand pollinated) were conducted onselect branches of 1or2 cultivars per farm. Additional variables including weather and flowering ground cover were recorded at each farmduring each visit. For sub-objective 1b (placement strategies), the Washington team measured the effects of honey bee hive placement across 12 grower sites, Oregon had 6 sites, and Michigan compared 8 sites. At each site, hives were either placed in a clumped or dispersed pattern. Honey bee visitation, hive activity, and fruit metrics were all measured as described above. Silicone bands were attached to study hives in order to measure pesticide exposure during bloom. These bands are being submitted for pesticide residue analysis. Data analysis was led by the Washington team for sub-objectives 1a (hive density) and 1b (hive placement) for presentation to our advisory board. For 1c (cost-benefit assessment), updating of the baseline enterprise budgets was initiated. 2: Determine pollination requirements and pollinator attraction across new and existing cultivars.Pollination requirements were investigated on7 southern highbush cultivars. Specifically, pollination treatments including no hand pollination, hand self-pollination, and hand cross-pollination were conducted to assess rates of auto fertility andself-fertilityfertilityorself-compatibilityfor each of 7 cultivars. Fruit set, fruit weight, and seed set were measured for all pollination treatmentson each cultivar. Additionally, the length of the effective pollination period was assessed in the cultivar Emerald.These activities generated some interesting preliminaryresults and were effective in refining methods that will be used in future years of the project. 3: Determine how variable weather conditions affect blueberry pollination.In Florida, the effect of temperature on the effective pollination period of the southern highbush cultivar Emerald was investigated by conducting pollination experiments under 12 C and 29 C temperature treatments. Additionally, nectar secretion rates over time were examined under different temperature treatments for the cultivar Emerald.In Michigan, the effect of extreme heat on blueberry pollen germination and pollen tube growth was investigated in vitro on several common northern highbush cultivars, including Bluecrop, Jersey, Liberty, and Elliott. Temperatures used in experiments ranged from 10 - 37.5 C and were assessed at 4 and 24 hours after exposure to heat treatments. A manuscript is in progress to publish these results, and more varieties will be tested using these same methods in 2022.Furthermore, during field data collection for objective 1 (stocking and hive placement effects), we also collected weather data immediately before and after measuring honey bee foraging in blueberry fields. We sampled across a range of environmental conditions to capture representative environmental variations in our field conditions. Environmental data collected included: temperature, relative humidity, barometric pressure, cloud cover, irradiance, and wind speed. Analysis of this data will help determine how weather conditions effect bee activity and successful pollination. 4: Develop predictive models of pollination, fruit set, and yield for creation of a Pollination Planner to improve pollination management decisions.Data from objectives 1-3 was delivered to collaborators in order to be incorporated into Objective 4's predictive models.A draft Pollinator Planner interface was developed and the interface was shared with meteorologists and our advisory board for feedback. 5: Deliver information on improved blueberry pollination to the industry.Information was delivered at a field day in Oregon with co-PIs Melathopoulos and Devetter. The whole team was able to share information via our project Twitter account (@BeesNBerries). A project website was developed to share project updates and relevant materials. On this website, we are publishing a regular newsletter that stakeholders can subscribe to. Team members from Oregon and Washington also contributed to two PollinNation podcasts on berry crop pollination.A survey was created for impact assessment and was distributed to blueberry growers across the country. Melathopoulos developed a card and infographic to promote responses to our grower survey. The draft Pollination Planner from Objective 4 was prepared for our fall advisory board meeting where we received feedback from members on the board. In Florida and Washington, individual grower reports were provided to all participating farms. These reports provided farm-specific data collected under Objective 1.

Publications

  • Type: Other Status: Published Year Published: 2021 Citation: Andony Melathopoulos (Host), 2021, Lisa Devetter - Blueberry Pollination Planner #192 (audio podcast episode), PolliNation Podcast. Oregon State University Extension Service. https://extension.oregonstate.edu/podcast/pollination-podcast/192-lisa-devetter-blueberry-pollination-planner
  • Type: Other Status: Published Year Published: 2021 Citation: Andony Melathopoulos (Host), 2021, Maxime Eeraerts - Sweet Cherry Pollination #190 (audio podcast episode), PolliNation Podcast. Oregon State University Extension Service. https://extension.oregonstate.edu/podcast/pollination-podcast/190-maxime-eeraerts-sweet-cherry-pollination
  • Type: Websites Status: Published Year Published: 2021 Citation: Blueberry Pollination website: https://blueberrypollination.org/