Source: MICHIGAN STATE UNIV submitted to
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
Sep 1, 2020
Project End Date
Aug 31, 2024
Grant Year
Project Director
Isaacs, R.
Recipient Organization
Performing Department
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
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
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 09/01/20 to 08/31/21

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.

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.


  • 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.
  • 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.
  • Type: Websites Status: Published Year Published: 2021 Citation: Blueberry Pollination website: