Progress report for SW21-923
Project Information
Local strawberries are in high demand throughout the Intermountain West, but outdoor production to meet demand is risky due to late frosts which threaten yields. Previous research at Utah State University (USU) has shown that high tunnel strawberry production could potentially meet consumer demand and be highly profitable when compared to outdoor or low tunnel production. Despite grower interest, adoption of high tunnel strawberry production in the West is low due to uncertainties over cultivar performance and best management practices for soil fertility and diseases using organic methods. High tunnel growing conditions can promote grey mold (Botrytis cinerea) and powdery mildew (Podosphaera aphanis) epidemics, requiring weekly fungicide application, a practice that is not sustainable for small scale growers using organic or natural growing methods.
Compost is a cost-effective organic fertilizer with potential for enhancing disease suppression but yield response can vary due to challenges associated with predicting nutrient release and plant uptake, which often translates to growers over applying or eschewing the use of compost altogether. Indeed, our preliminary research has shown considerable variability in growth and nitrogen (N) uptake among strawberry cultivars when grown on slow-release organic sources of N like composts. Compost-mediated resistance can also be complemented through use of microbial biological control agents (mBCAs), which can be directly applied by growers or transferred to flowers by pollinators such as bumblebees. While strawberries are self-pollinating, pollinators and their foraging activity can have synergistic effects on grower outcomes through increasing berry size and yields, and by vectoring mBCAs.
This project will improve management options for sustainable strawberry production by harnessing synergies between season extension, cultivar identity, nutrient uptake on compost, and disease suppression by addressing the following objectives: 1) assess strawberry cultivars for nutrient uptake and growth on less readily available organic nutrient sources, 2) assess how mBCA effectiveness, both singly and in mixtures, varies with strawberry cultivar and compost use 3) evaluate use of bumblebee pollinators to enhance biological control and yield 4) assess market value and consumer preference for local strawberries, 5) improve grower and student understanding of high tunnel strawberry production through on-farm trials field days, training events, the development of new online resources and course material. The most promising cultivar/management combinations will be tested and showcased on five commercial farms, with results published in factsheets and videos. This research is unique in that it explores innovative and sustainable ways to solve common production problems. Recent data published by the National Agriculture Statistics Service shows strawberries are among the top selling organic crops. With improved management options, local farms could meet consumer demand, bolster local economies, and improve environmental impacts. The information generated will help growers to potentially transform their production systems, reduce or eliminate reliance on toxic chemicals, improve nutrient management and soil health, and meet market demand for local, sustainably produced strawberries.
The long-term goal of this project is to increase the production of strawberries for local markets, improve soil nutrient and disease management, and reduce reliance on purchased inputs through addressing the following specific, short-term objectives: 1) assess cultivars for nutrient uptake and growth on less readily available organic nutrient sources such as compost, 2) assess how mBCA effectiveness, both singly and in mixtures, varies with strawberry cultivar and compost use 3) explore the use of bee pollinators to enhance biological control and yield and 4) assess market value and customer preferences for local strawberries grown under various production schemes and 5) Improve grower and student understanding of high tunnel strawberry production through on-farm trials, field days, training events, the development of new online resources and course material. Initial selection of cultivars and mBCAs occurred in the greenhouse and laboratory in year one, with a subset field tested at the USU Student Organic Farm in years one through three. The most promising cultivar and management combinations will be tested and demonstrated on five commercial farms in years two and three. Five commercial growers and one student farm manager will advise the project through twice yearly meetings throughout. Results will be showcased in Utah and five neighboring states through on-farm tours and workshops, and published in factsheets, videos, and peer-reviewed publications
If funded, we will begin screening cultivars in the greenhouse in April 2021 in time for plug plant production in July 2021. The first trials will be planted in early September 2021 and harvested in the spring of 2022. The second trials will commence in early April 2022 for harvest in the late summer and fall of 2022. A second round of trials will commence on the same schedule but starting in the fall of 2022 and spring of 2023.
Amino acid uptake measurements and mBCA leaf bioassays will commence in the fall of 2021 and will be completed within a year. Bumblebee trials will commence in the spring and late summer of 2022 to coincide with blossom and fruit set. A second round of bumblebee trials will commence in the spring and late summer of 2023. Economic field experiments will take place in 2022.
Grower advisory meetings will be held in October and March of each year. A high tunnel construction workshop will be held on the USU Student Organic Farm in August 2021. Five additional high tunnel construction and strawberry management workshops will be held in neighboring states in years two and three. Field days will be held in April or May in years two and three of the project. Post-program evaluations will be conducted on site or online directly after all field days, workshops etc. Follow-up surveys to asses producer adoption will be conducted one and two years after each program.
Data on yields, input costs and revenue will be collected from grower participants during each spring or fall planted trial. Data will be used to update an existing peer reviewed strawberry production budgets in the final year of the project. Outreach and journal articles will also be finalized in the final year of the project.Gantt chart
Cooperators
- - Producer
- - Technical Advisor - Producer (Educator)
- - Technical Advisor - Producer
- - Technical Advisor - Producer
- - Technical Advisor - Producer
- - Producer
- - Producer
- - Producer
- - Technical Advisor - Producer (Educator and Researcher)
- - Technical Advisor - Producer (Educator)
- - Producer
Research
We hypothesize that there is a positive relationship between growth and amino acid uptake on compost in the greenhouse and growth and productivity on compost in the field.
We hypothesize that more diverse mBCA treatments will be more effective at preventing disease than those that are less diverse and that strawberry plants grown on compost will be most responsive to mBCA treatment.
We hypothesize that use of bumble bees in high tunnels will have synergistic effects on strawberry health and yield quality.
Objective 1) Assess strawberry cultivars for nutrient uptake and growth on less readily available organic nutrient sources such as composts.
(i) Rationale and Hypotheses. We built on preliminary data already collected that suggests strawberry cultivars show considerable variability in growth on slow-release organic sources of N like compost (Figure 1; Reeve et al. 2017) and take up organic molecules such as amino acids directly (Reeve et al. 2008). We have been using greenhouse trials to select strawberries with extreme differences in growth on compost and confirm these results in high tunnels. We hypothesize that there is a positive relationship between growth and amino acid uptake on compost in the greenhouse and growth and productivity on compost in the field.
Figure 1. Tissue nitrogen (N; percent), shoot dry weight, N use efficiency (NUE) and leaf chlorophyll in strawberry cultivars grown on compost with N-free vs complete nutrient solution. The line shows the 1:1 relationship between strawberry parameters grown on compost vs. complete nutrient solution. Points significantly above the line indicate cultivars that are more efficient at obtaining N from compost than from mineral sources.
(ii) Approach. Twenty-nine commercial cultivars were obtained from nurseries (e.g. Nourse Farms, Whately, MA) and propagated according to Rowley (2010). Best and worst performers (as controls to test relationship between N uptake and performance in the field) from preliminary trials (Figure 1) were included. The most divergent cultivars were planted in high tunnels at the Student Organic Farm and four commercial farms (see below). Plug plants were grown with and without compost (Millers Inc, Hyrum UT) in 6” pots with 4 reps and analyzed in a completely randomized design with two treatments (cultivar, with/without compost). Compost treated plants were irrigated with N-free fertilizer, while control plants received regular soluble fertilizer. N mineralization was estimated in pots without plants maintained at field capacity with N-free fertilizer. All pots were leached four times over the course of the experiment with 300 ml water with leachate collected and analyzed for nitrate and ammonium (Lachat Instruments, Loveland CO). Leaf chlorophyll measurements were taken at the start and end of the experiment using a chlorophyll meter (Apogee Instruments, Logan UT). Plants were harvested after nine weeks, shoots and crown separated, and wet/dry weight and tissue N recorded. Amino acid uptake will be measured on eight best and worst performing cultivars on compost according to Reeve et al. (2008). Briefly, C14 labelled glycine and N15 labelled nitrate and ammonium are added to soil containing a rooted strawberry plant. The surface of the soil is sealed with wax to prevent atmospheric uptake and the plants placed in a vented manifold system. Glycine, nitrate, and ammonium uptake are determined after 24 hours.
Fall and spring plantings of strawberries grown with compost alone (Millers Inc, Hyrum UT) vs compost + soluble N fertilizer (fish emulsion on organic farms) were established on the USU Student Organic Farm and a total of six commercial farms in August/Sept 2021 and Feb/March 2022 and will be repeated in years two and three of the project. At the student farm, one 70 x 14ft tunnel was dedicated to fall and one to spring production and on farm trials were sized according to grower interest and available space. Eleven compost/cultivar treatment combinations (3ft. of bed per treatment with 12 plants per plot) with three replicate plots were established per high tunnel. Best performers selected in greenhouse trials as well as Chandler and Seascape that are expected to be poor were included to test the relationship between growth on compost and performance in the field. Optimum planting dates of September 1st for spring harvested berries and Feb 15th for fall harvested berries have been identified for a limited number of varieties. The on-farm fall plantings included two additional planting dates to optimize planting dates for a wider selection of locations and cultivars. Fertilizer was applied based on industry recommendations as a split plot at four locations.
Total and marketable berry yield, fruit size, plant growth, leaf chlorophyll, leaf N content and disease incidence will be measured. Soil health indicators (organic matter, microbial biomass, available soil nutrients, pH and EC) will be assessed each year at planting at 0-30 cm according to Gavlak (2003) and Anderson and Domsch (1978). Data from fall and spring plantings will be analyzed separately using a random complete block design with two factors (cultivar and compost) with harvest time as repeated measure. Additional replicated trials will be located on seven commercial farms using locally available compost. While it is anticipated that the data collected on these trials will also be of sufficient quality to support research and extension publications, the primary goal of the on-farm research is the hands-on training of early adopter growers and to facilitate robust economic analysis. The number of treatments deployed per site will depend on the space growers devote to the project, and on the objectives that best fit their farm operation (ex. spring vs. fall production system).
Objective 2) Assess how mBCA effectiveness, both singly and in mixtures, varies with strawberry cultivar and compost use.
(i) Rationale and Hypotheses. Application of mBCAs represents a sustainable alternative for disease control. To date, a handful of mBCAs have been screened for use in limiting powdery mildew (Podosphaera aphanis) and grey mold (Botrytis cinerea) development in strawberry (Sylla et al. 2013). Though single and paired species mBCA treatments demonstrate promise, they remain subpar to fungicides (Pertot et al. 2008; Silla et al. 2013). Increasingly, it is recognized that a positive relationship exists between microbial community diversity and resistance to pathogen invasion (Santhanam et al. 2015). Thus, we hypothesize that more diverse mBCA treatments will be more effective at preventing disease than those that are less diverse and that strawberry plants grown on compost will be most responsive to mBCA treatment.
(ii) Approach. mBCA treatments [single, paired, or consortia (i.e., three species)] were tested for their efficacy against mildew and mold. The subset of best and worst performing cultivars identified in Obj. 1 were used for this assay, grown on and off compost. To test efficacy, we used a detached strawberry leaf disc bioassay, following Sylla et al. (2013). Briefly, leaf discs (1 cm diameter, N = 30 per mBCA treatment and cultivar/soil combination) were sourced from plug plants, grown as above, and treated with mBCA suspensions (~1 × 107 CFU ml−1). The Control treatment consisted of leaf discs dipped in sterile Ringer solution. Treated discs were incubated at 25°C (65% RH), with an alternating 12 hr. light/dark photoperiod. After 24 hr., leaf discs were inoculated with P. aphanis or B. cinerea conidia and incubated to allow for pathogen development. Leaf discs were processed to determine levels of conidia production, using microscopy and a Thoma counting chamber to determine the number of conidia per cm2 of leaf. The following mBCAs were tested: Aureobasidium pullulans, Bacillus subtilis, Metarhizium anisopliae and Streptomyces globisporus. These species were chosen as they have demonstrated potential for suppressing mold and mildew (Sylla et al. 2013; Kim et al. 2019), are effectively dispersed by pollinators (Dedej et al. 2004; Kapongo et al. 2008; Russell et al. 2019), and to a degree (a subset of listed species), are commercially available to growers. mBCA treatments include the following possible species compositions (14 total: four one-species communities, six two-species communities and four three-species communities) drawn from the four-species pool. These in-vitro assays will be used to inform cultivar and mBCA treatments for field trials (Obj. 3).
Objective 3) Evaluate use of bee pollinators to enhance biological control and yield.
(i) Rationale and Hypotheses. Cross-pollination can significantly enhance strawberry yields, fruit quality, shelf-life, and commercial value (Klatt et al. 2014; Wietzke et al. 2018; MacInnis and Forrest 2019). Moreover, pollinators (e.g., bumble bees) naturally disperse microbes among flowers and can vector with considerable success (Yu and Sutton 1997; Kapongo et al. 2008; Russell et al. 2019). We hypothesize that use of bumble bees in high tunnels will have synergistic effects on strawberry health and yield quality.
(ii) Approach. Assessment of bee effectiveness for biocontrol, yield enhancement, and how this varies with soil background, will be tested through cage trials, performed in two high tunnels at the USU Student Organic Farm in years 2 and 3 of the project. Commercial bumble bee colonies (Bombus impatiens, Biobest Group) will be obtained and fitted with an mBCA inoculum dispenser (Yu and Sutton 1997; Al-mazra’awi 2004). Each cage (i.e., treatment) will contain 32 strawberry plants. The RCBD experiment will be replicated 4 times. Treatments will consist of control treatment with neither inoculum nor bees, mBCA inoculum sprayed alone, bees alone, and mBCA inoculum + bees. Cultivar performance data (Obj. 1), plus results from Obj. 2, will inform the identity of mBCA/cultivar combination tested initially. Half of the plants will be treated with either control or compost-amended soil as in Obj. 1.
After establishing caged arrays, we will introduce colonies to allow for bee foraging and dispersal of mBCA inoculum. Following a three-day period of bee activity, flowers and leaves of eight randomly selected plants per soil treatment will be artificially inoculated with either mildew or mold conidia. After six days, leaf and flower samples will be harvested for disease assessment, with mBCA dispenser removed from colonies. After each tissue-sampling, remaining inoculum will be dried and weighed to determine the amount delivered. Finally, we will assess fruit yield and quality by measuring fruit production, mass, shape (length:diameter ratio), soluble solids, titratable acidity and total phenolic compounds.
Objective 4) Assess market value and consumer preference for local strawberries.
One project graduate student will work with growers starting in year two to collect information to revise and update previously-published cost of production budgets (Maughan et al., 2014). Pricing estimates will be based on current local pricing of strawberry cultivars produced collected from the USU farmers’ market and dining outlets (e.g., Luke’s Café), the Cache Valley Gardeners Market, Ogden and Salt Lake City farmers markets and also through interviews with local chefs and retail outlets. Cost estimates will be based on inputs used during study trials and those provided by local vendors. Cost of production budgets will be used to educate growers on production and marketing methods at Extension field days, workshops, webinars, and online. These budgets provide growers will good estimates of the potential profitability (by cultivar and production methods) of strawberries under reduced chemical and organic production systems, thus enabling growers to better assess and adopt study recommendations.
Consumer preferences and willingness to pay for successful strawberry cultivars and production systems will be evaluated through economic field experiments conducted with Northern Utah residents. Experiments will include blind sensory analysis of strawberry cultivars followed by a survey including choice sets to determine consumer preferences and willingness-to-pay (WTP) based on strawberry product pricing, strawberry sensory and production attributes, as well as consumer psychographics and demographics (Barnes et al. 2014; Bosworth et al. 2015; Drugova et al. 2020). Field experiments will be conducted at farmers’ markets (Logan, Ogden, and Salt Lake City), the USU campus, and local retail outlets. Market viability studies such as these are an important part of understanding consumer interest in new products/production methods such that product pricing, attributes, sales venues, and promotional messages are appropriate for the target market(s), which are also identified through this analysis. A study on consumer interest and WTP for eco-friendly and organic peaches found that reduced chemical and eco-friendly production methods are valued by consumers in Northern Utah (Curtis et al., 2020).
Objective 1) Assess strawberry cultivars for nutrient uptake and growth on less readily available organic nutrient sources such as composts
The growth of twenty-nine commercial strawberry cultivars were compared on compost versus commercial fertilizer in the greenhouse. Many of the cultivars of interest were already sold out for the season by the time funding was awarded for this project so we based our initial selection on availability. As with our preliminary findings considerable variation in growth on compost between cultivars was found Fig. 2). There was broad agreement between the results of our preliminary trials and follow-up trials with more vigorous plants producing more biomass in both sets of trials. Unlike previous trials however, all cultivars performed much worse on compost which may be attributed to year-to-year variability in the compost used. The exception was Monterey but given that very little growth occurred on conventional fertilizer for this cultivar, this is likely an anomaly. Given this and the fact that many of the cultivars we were interested in were already sold out at the commencement of the study in spring of 2021, we decided to conduct a second round of greenhouse trials in the fall of 2022. Amino acid uptake experiments will be delayed until after the second round of greenhouse trials have been completed.
Fig. 2. Change in biomass between initial and final plant weights when grown on conventional fertilizer vs. compost in a greenhouse trial conducted in the winter / spring of 2021-2022. Unlike previous experiments all cultivars performed much worse on compost than conventional fertilizer. We attribute this to differences in compost quality.
Sub-selections of the 29 cultivars were planted in high tunnels at the USU student Organic Farm and six commercial farms in August and September of 2021 and February and March 2022 for spring and fall production respectively. Selections were made to include representatives from the best and worst performers from the greenhouse trials in addition to other cultivars of interest to our grower cooperators. Compost was applied across all cultivars where needed based on soil test results. The USU plantings and plantings on two commercial farms included a second treatment with and without supplemental fertilizer. Plant survival, number of crowns, runners and leaf chlorophyl were recorded. Total and marketable yield data will be collected on fall plantings this spring.
Preliminary results from high tunnels show considerable variability in plant growth and leaf chlorophyll between cultivars as well as considerable site to site variation. At the student farm, Allstar, Galleta, AC Valley, Seascape and Camerosa were our top ranked cultivars while an aggregated ranking for our commercial farm collaborators were quite different with Sparkle, Honeoye, Mayflower, Allstar and Malwina doing best so far. We had some poor establishment, especially on our commercial farms which we contribute to a combination of a high degree of variability between cultivars in the degree of root development of the plug plants at planting, poor soil health, high temperatures at planting and grower inexperience. One farm in particular had very high soil salinity and poor soil structure and even though they were actively working to address the problems through leaching and organic matter inputs, the majority of the cultivar showed symptoms of salt burn. Two cultivars that seemed relatively unaffected were Camerosa and Mara des Bois, although Mara des Bois performed very poorly at other locations due to high symptoms of iron chlorosis. Going into our second year, we plan to provide several additional weeks for plug plant establishment, and we are actively working with our collaborators to improve soil conditions and management experience of strawberry.
Yield results from the fall 2021 and spring 2022 plantings reflected the considerable variability in plant growth, crown number and leaf chlorophyll between cultivars reported previously, as well as considerable site to site variation. Overall, yields were about half what we would expect based on previous research at USU. Soil test results and a lack of nitrogen response suggests yield problems were due to heat stress rather than nutrient limitations, although iron chlorosis was a serious problem in some cultivars in spite of regular applications of chelated iron and trace elements at the student farm. Our grower collaborators chose not to apply trace elements due to the expense of that treatment after project support would end. Spring and fall temperatures in 2022 were unusually high in Utah reaching in to the 90 to 100 degrees Fahrenheit for weeks at a time in Cache Valley. Top Ranking cultivars based on yields at the student farm were Seascape, AC Valley, Chandler, Yambu, Camerosa and Galletta, reflecting our preliminary rankings based on plant growth in year 1. The top yielding fall planted cultivars at Lost Creek Farm were Galletta, Chandler, Yambu, Mayflower and Jewel. Neither Steep Mountain, or Red Acre Farms had any appreciable yield due to pest problems (ants and woodlice) although in general the growers ranked their favorites out of these same shortlists above. Two promising cultivars from the Steep Mountain farm were Dickens and Sparkle, so these were included in the new 2022 fall planting. Petersen farm experienced very poor results due to stand establishment and management issues and decided not to continue planting strawberries.
Yield based cultivar ranking of day neutral strawberries planted at the student farm in the spring of 2022 were Evie 2, Monterey, Cabrillo, Charlotte and Seascape. Six commercial farms were involved in the spring planted trials although many experienced production issues with pests and tunnel temperature management. While we have been helping the growers to identify potential organic pest management protocols for strawberry, many of the issues were likely exacerbated by their use of no tillage systems involving heavy use of organic mulches. Other growers are discovering that the intensive early fall and spring tunnel temperature management required by strawberries is beyond them. The two growers who supplied yield data ranked the cultivars as follows a) Mara des Bois, Sweet Ann, Cabrillo, Monterey and Seascape, and b) Evie 2, Monterey, San Andreas, Mara des Bois and Seascape. Consumer trials suggested that Evie 2 and Mara des Bois were ranked poorly for taste, so for this reason these cultivars were dropped from the spring 2023 selections.
The growth of twenty-six commercial strawberry cultivars were compared on compost versus commercial fertilizer in the greenhouse in the fall / winter of 2022-2023. The selection included best and worst performers from the previous greenhouse trial and also included new selections that were commercially available at the time. As with our previous findings considerable variation in growth on compost between cultivars was found. There was broad agreement between the results of our preliminary trials and follow-up trials with more vigorous plants producing more biomass in all sets of trials. All cultivars performed much worse on compost which was attributed to the increase in the C:N ratio of the compost used. The compost was sourced from the same supplier as in previous years and was made of the same ingredients but appeared to contain a larger proportion of wood chips than in the past. Nevertheless, some cultivars grew considerably better on compost than others (Fig. 4), confirming our hypothesis that there would be variability in the ability of strawberry to grow on compost as an N source. Amino acid uptake experiments were delayed due to a lack of runner production over the winter and will occur in the fall of 2023. They will include best and worst performers from the greenhouse trials.
Fig 4 Greenhouse trial winter 2022-2023
Fig. 4. Change in biomass between initial and final plant weights when grown on conventional fertilizer vs. compost. Most cultivars continued to perform worse on compost than conventional fertilizer, however, some cultivars perform much better on compost than others.
Sub-selections of the 26 cultivars were planted in high tunnels at the USU student Organic Farm and seven commercial farms in August and September of 2022 and March 2023 for spring and fall production respectively. Selections were made to include representatives from the best and worst performers from the greenhouse trials in addition to the best performing cultivars from previous field trials. Compost was applied across all cultivars where needed based on soil test results. The USU plantings and plantings on one commercial farm included a second treatment with and without supplemental fertilizer. Plant survival, number of crowns, runners and leaf chlorophyl were recorded. Total and marketable yield data were collected from the fall 2021 and spring 2022 plantings.
Establishment in the fall of 2022 was much improved over the first year which we attribute to a combination of earlier planting and improved cultivar selection. An exceptionally cold and wet winter in early 2023 resulted in considerable winter kill of many of our top-ranking cultivars. While Dickens, Galletta and Flavorfest showed no appreciable winter kill, almost no Yambu, AC Valley, Seascape, Chandler or Mayflower plants survived at the student farm. Spring flooding after unprecedented snowfall in Cache Valley killed the majority of plants at the Lost Creek site. This illustrates the need for multi-year trials under a range of environmental conditions to identify the best performers in our growing conditions.
Objective 2) Assess how mBCA effectiveness, both singly and in mixtures, varies with strawberry cultivar and compost use
In Year 1, mBCA effectiveness against mold was screened for in a subset (N = 11) of cultivars available. Given limitations on the number of plants available for each cultivar, we limited our mBCA screening to a single microbial species, the basidiomycete fungus Aureobasidium pullulans. Our reasoning for choosing this sole species is that it 1) has documented success as an mBCA against an array of plant pathogens, including those that affect strawberry, and 2) it is commercially available (Blossom Protect, Westbridge Agricultural Products), thus easily accessible for growers for use in high tunnels. In our preliminary screening with these 11 cultivars, the general trend was for A. pullulans to suppress mold growth, nearly completely. The only exception was Mara du Bois, which still experienced considerable mold growth when challenged with the pathogen following mBCA treatment. This cultivar also displayed the least resistance against mold in the control treatment (water spray), experiencing nearly two-fold higher growth than other cultivars screened. Finally, among control plants, cultivars AC Wendy and Chandler exhibited high levels of resistance.
Microbial biological control agents (mBCAs) have considerable potential for use in high tunnel systems for disease control. When combined with other disease and nutrient management approaches (i.e., compost addition), potential synergies may occur with respect to disease resistance. We evaluated this potential, as well as how efficacy could vary across background, screening 13 June-bearing cultivars in summer 2022. Leaf material was harvested from mother plants maintained in the USU research greenhouse for plug plant production. These leaves were used for disk generation, which were prepared and treated following methods outlined above, with the exception of focusing on a single mBCA, Autreobasidium pullulans. This decision was made after consideration of product accessibility for our grower producers and others in the region. We felt evaluation of a readily available product that has already shown some promise for mold control in strawberry would be most impactful. This prior work however had not given consideration to variability in efficacy among cultivars, as mBCAs may vary in both establishment and compatibility with genotype background.
While mBCA application generally reduced B. cinerea growth, the magnitude of this response varied significantly with cultivar background (Fig. 5). In these cultivars, and a subsequent screening of day-neutral varieties (seven in total), we are also evaluating A. pullulan’s potential mode-of-action. Briefly, excised leaves from each cultivar were treated with mBCA following methods outlined above. Leaf subsamples were then harvested at different time-points post-mBCA treatment to evaluate the potential for mBCA priming of host defenses. To assess this, we are extracting RNA from leaves and evaluating expression of genes associated with anti-fungal defense. This research is ongoing, with results to be combined with those from the leaf disk assays in a publication that will be prepared this fall for submission for peer-review. An additional extension publication will also be generated, highlighting variability among cultivars in mold resistance and use of mBCAs for disease management.
Objective 3) Evaluate use of bee pollinators to enhance biological control and yield
For this objective, we tested the hypothesis that bumble bees could have synergistic effects on strawberry health and yield quality when used in high tunnels during bloom. To do so, in summer 2022, a high-tunnel experiment was established (see methods above) at the student organic farm at USU. Three cultivars (AC Valley, Chandler, Galetta) were chosen for use, with plug plants generated in the research greenhouse (July), then transplanted into subplots within beds that were either amended with compost or not (August). Pollination and mBCA treatments were applied in spring 2023 (April and May) and harvested fruits are currently being processed and compared for size and quality metrics, with analyses ongoing. This experiment will also be replicated, with planting to occur this August 2023. Final results from the 2022 planting will shared in the final report, along with data from this forthcoming trial.
Fig. 3 Microbial biocontrol agent (mBCA) to grey mold. Grey mold suppression was excellent on all cultivars selected except Mara des Bois.
Figure 3 Strawberry Response to Microbial Biocontrol Agents
Objective 4) Assess market value and consumer preference for local strawberries
A graduate student was identified to conduct this work and attended a professional development school at MSU in late May 2021 to learn the choice task set up and modeling that we will need to do.
Low yields attributed to extreme heat in the spring and fall of 2022 meant that insufficient berries were available for full market evaluation research at farmers markets. However, small scale taste tests of all cultivars were completed at the student farm and by participating growers and these results were used to inform cultivar selection for the new fall 2022 and spring 2023 plantings. In addition, all field experiments were designed and tested and will be conducted at farmers’ markets and retail outlets in Fall 2023. Additionally, a survey of Utah residents will be conducted online via Qualtrics in August of 2023 to determine consumer preferences and willingness-to-pay (WTP) based on strawberry product pricing, production attributes, and consumer psychographics and demographics. The survey is complete and awaiting IRB approval.
Research Outcomes
Education and Outreach
Participation Summary:
Outreach on the project is on track. We held an initial grower advisory meeting early in the project where we discussed general strawberry production methods and invited input on initial cultivar selections and interest in preliminary planting date trials. Four out of five of our producers opted to participate in the preliminary trials and four additional commercial farmers, Ranui Gardens in Hoytsville, Utah, Weeks Berries in Paradise, Utah, Clay Farm in Kaysville Utah and Jaydee Gunnell's operation which he runs alongside his extension duties, joined the trials planted in the spring of 2022. Four commercial farms participated in the fall 2022 and spring 2023 plantings (Steep Mountain Farm, Lost Creek Farm, Clay Farm, and Red Acre Farm). Due to attrition from our earlier cohort, we ramped up site visits to every other week on nearby farms to assist with plot establishment and maintenance, assessment and to answer any questions. More distant farms have received two onsite visits per year together with online support.
Initial results were showcased at the Utah Urban and Small Farms Conference on 24 February 2022 and a subsequent USFC Season Extension Field Day held on 24 Mar 2022. The Utah Urban and Small Farms Conference Data featured an invited presentation by Clare Sullivan from Oregon State University on her work on small farm strawberry production, also funded by WSARE. Our initial results were also shared as part of a virtual season extension workshop sponsored by Wasatch County Extension on 18 March 2022.
To continue to extend the results to potential end users, we organized and conducted three extension workshops in neighboring states in June 2022, March 2023 and April of 2023. The first was held at the Western Montana Research and Extension Center, Corvallis, MT. We had about 25 people attend the strawberry presentation. The majority were small acreage producers focused on alternative crops and alternative production strategies. The presentation was followed by a tour of some of the Center's alternative crop plots.
The second (March 23) was in Southeastern Idaho (Rigby) and had 100 participants, 70 in person and 30 virtual, representing multiple counties (Jefferson, Madison, Teton, Fremont, Bonneville and Bingham). The hybrid nature of this meeting was required because of limited seating at the venue, and a large demand for information on the topic. To broaden the potential audience, the workshop was expanded to cover a wide range of topics beyond strawberry, including: high tunnel design considerations and temperature management, soil management in tunnels, cut flower production, warm season vegetables, marketing and economics. The workshop speakers included 3 USU extension specialists, as well as the Jefferson and Madison county Extension agents and a representative from NRCS. Participants completed a feedback survey, with 63.6% of respondents rating the workshop as “Excellent” and 27.3% giving a “Very Good” rating. Among respondents, 52.7% indicated their confidence in producing strawberries as “Much higher” as a result of attendance.
The third workshop was on 6 April in Caldwell, Idaho and was co-organized by a regional small acreage specialist based in Boise. This second workshop had a lower enrollment cap and ended up with 21 in attendance. Topics presented were similar to the previous workshop, but also included some hands-on instruction on high tunnel and low-tunnel designs and management. The grower response survey had very similar levels of satisfaction with the overall workshop, but confidence in knowledge gained was less dramatic, with 14% indicating “much higher” and 92% indicating “higher” confidence in their ability to manage strawberries. One side benefit of this second workshop was a referral provided by one of the class participants for a neighbor that was already experimenting with commercial strawberry production. This grower enrolled in our fall trials planned for 2023.
We also gave a presentation to the 2023 Urban and Small Farms Conference in February that featured early results from this project as well as cultivar information generated in Oregon and New Mexico. This was a virtual conference, with 660 people registered to attend the fruit session. The strawberry talk had 135 live attendants, although others may have viewed the recorded the talk later which was made available to all who registered. Registrants were primarily from Utah (most from the Wasatch Front area but also a surprising number from remote parts of the state). We also had representation from all the neighboring states.
Of the registrants, breakdown by state was as follows (top 8 shown):
|
UT |
81.7% |
|
ID |
4.1% |
|
CO |
2.9% |
|
WY |
2.4% |
|
MT |
1.2% |
|
NM |
0.9% |
|
AZ |
0.6% |
|
NV |
0.6% |
There were also a few registered from outside the US (Canada, Mexico, Philippines, Bangladesh, Pakistan).
Finally, we held a three-hour workshop on May 16th 2022, on high tunnel strawberry production for our grower collaborators and student farm interns participating in the project. The workshop included presentations on previous and new strawberry research at USU, updates from participating growers, a discussion on high tunnel construction and management including lessons learned so far and a tour of the student farm strawberry cultivar trials. A grower advisory meeting was also held on Dec 13th 2022.
Summary of Outreach activities/presentations.
Presentations to date:
24 Feb 22 Strawberry management systems for Utah. Utah Berry Growers Association Meeting. Utah Urban and Small Farms Conference, (Virtual, 89 in attendance).
18 Mar 22 Tunnel design, temperature management and fruit crop options for Utah. Season Extension Workshop, USU Extension Wasatch County, (virtual, 55 in attendance)
24 Mar 22 Strawberry management in high tunnels. Season Extension Field Day for the Urban and Small Farms Conference, Greenville Farm (60 in-person attendance).
16 May 22 Strawberry project workshop including grower advisory board and grower and student project participants (approximately 14 in attendance).
6 June 22 Strawberry high tunnel management research from Utah. Western Montana Research and Extension Center, Corvallis, MT (approximately 25 in person attendance, mostly small-scale farmers).
13 Dec 22 Grower advisory meeting. Included brief updates from researchers and grower participants followed by a discussion.
Feb 23 Urban and Small Farms Conference (135 online attendance with up to 660 registered and potentially viewing the material afterwards).
23 Mar 23 High Tunnel production workshop held in Southeastern Idaho (Rigby) with had 100 participants, 70 in person and 30 virtual.
6 Apr 23 High Tunnel production workshop in Caldwell, Idaho (21 in attendance).