Progress report for FNE25-117
Project Information
Levo International, Inc., is a nonprofit organization based in the Hartford, Connecticut area which seeks to improve food security through the use of simplified forms of hydroponics, the growth of crops in water-based nutrient solution. Hydroponics is a sustainable form of agriculture as it can improve water and fertilizer use efficiency, increase yields per area, and can be used in any location with access to light.
Strawberry production is a $2 billion industry in the U.S., however 99% of it occurs in California and Florida, largely in field settings. Hydroponics is used widely in countries such as the Netherlands and Japan for strawberry production. Hydroponics as typically done requires high initial capital costs and technical expertise, leading to limited adoption in the U.S. Simplified forms of hydroponics, such as those deployed by Levo International, Inc., decrease the required costs and expertise associated with hydroponic production.
With our first objective we will establish a strawberry production process in simplified hydroponic systems and an associated Integrated Pest Management Plan. We hypothesize that Kratky systems using an IPM plan produce strawberries as well as field production in the Northeast, enabling an increase in strawberry production in the Northeast region. It is thought that inoculation of strawberry roots with Trichoderma species and manual pollination of strawberry flowers improves yields. Our second objective will test the hypotheses that these techniques positively impact strawberry yields. Our results will aid Northeastern strawberry farmers to make decisions on when these techniques make economic sense.
Our first objective (Obj. 1) is to establish a strawberry production process in Kratky systems including an Integrated Pest Management (IPM) plan. We hypothesize that Kratky systems using an IPM plan produce strawberries as well as field production in the Northeast.
Our second objective (Obj. 2) is to test the impact of Trichoderma inoculation and manual pollination on strawberry yields and disease incidence. These are techniques that are thought to improve strawberry yields, but there is limited work to this point to test the importance of either of these techniques. We hypothesize that Trichoderma inoculation protects plants from disease in a Kratky system, resulting in lower disease incidence and higher yields. We hypothesize that manual pollination of strawberry flowers improves yields and decreases the rates of malformed fruit.
In 2021 approximately 13.5 million U.S. households faced food insecurity (1). Food insecurity tends to concentrate geographically. Food deserts are locations without access to fresh food. These frequently occur in U.S. cities and disproportionately affect communities with higher percentages of people of color (2). The distance one has to go to find food is especially important for Americans who do not have cars. One study found that of Americans who are the primary grocery shoppers for their family, those without a car had a significantly higher risk for facing food insecurity (3). There is a need for more retail options for healthy produce so that cars, which are expensive, are not required for a family’s food security. Urban agriculture is one important component of creating access to healthier food choices for many suffering from food insecurity, but obstacles of urban agriculture are real.
Hydroponics, the growth of plants in a water-based nutrient solution, offers a mechanism for urban agriculture and increased sustainability. Several challenges are associated with urban agriculture including soil contaminants, water availability, and changes in climate and atmospheric conditions. Utilizing hydroponic farming methods can address these challenges. Hydroponics allows for year-round local production which means that transportation and importation costs can be decreased. Hydroponics allows for production regardless of the land type and can therefore be done in urban environments near the highest demand for food. Hydroponics can promote increased yields, as precise nutrient applications and environmental controls support optimum plant health. Additionally, hydroponic agriculture can improve water and fertilizer use efficiency due to direct application and recirculation.
Strawberry production in the Northeast could be increased using hydroponics. The strawberry production industry in the United States is valued at over $2 billion dollars (4). However, only 1% of the strawberry production in 2020 came from outside of California and Florida (4). The majority of production in the Northeast comes from only a few large producers. In addition, the majority of U.S. strawberry production occurs in field production settings. On the other hand, a large portion of strawberry production in top producing countries such as Japan and the Netherlands is largely done hydroponically.
One of the main limiting factors preventing hydroponic strawberry production is cost up front as hydroponic systems typically require expensive construction and expensive materials (5). For example, most production is done in systems with substrate production which requires large amounts of artificial substrate such as perlite and coco coir to replace the role of soil in field production (6). Additionally, up to 30-40% of the fertilizer inputs used in traditional strawberry hydroponic systems are lost as waste due to efflux requiring continual fertilizer additions (6). Sophisticated environmental controls and nutrient monitoring and management are not only expensive but require skilled management. These expensive inputs require high yields and allow little room for failures in production. This reality prevents growers with less capital from being able to produce strawberries and helps explain why much of U.S. production still occurs in large-scale field settings (4).
There is now strong evidence to support our hypothesis that simplified hydroponic methods can be used to improve the viability of hydroponic strawberry production by decreasing costs. Simplified hydroponic systems retain many of the benefits of hydroponics, such as land use flexibility and increased water use efficiency but built with simple supplies and require minimal maintenance (7–10). Over the past seven years we have conducted operations using two main types of simplified hydroponics systems: Kratky systems and Levo DFT systems. The Kratky system is the most straightforward form of hydroponics available as it requires an initial setup and then can be left alone until harvest (10,11). In collaboration with researchers at the University of Connecticut, The Ohio State University, and Cornell University, we have found that this approach actually can produce lettuce as well as much more energy and time intensive approaches (12). This system can be used for a wide range of crops, including strawberries (11,13,14). We propose to use the Kratky method to produce strawberries. This will eliminate waste as it is a closed system with 0% efflux and minimizes complexity of system management.
The adoption of simplified hydroponic technology is limited by plant disease risks. As
hydroponic systems require the shared use of water between multiple plants, disease risks are high. One virulent pathogen can spread quickly and cause massive damage, even complete loss of a crop. Large hydroponic operations often attempt to eliminate disease pressure by enforcing a strict sanitation policy and completely enclosing and controlling the greenhouse environment. This is not practical for a simplified hydroponic operation, as complete environmental control is expensive and does not allow for growers to take advantage of ideal growing conditions when they naturally occur.
To manage disease losses, we will develop a sustainable integrated pest management (IPM) plan. This will be created and assessed in collaboration with the Connecticut Agricultural Experiment Station. We have identified root rot, Botrytis fruit rot, anthracnose, powdery mildew, and insect pressure as critical disease and pest problems in Northeast strawberry production. We will use a combination of biological control and organically labeled products to control these diseases.
One of the challenges associated with disease management is a decreased diversity of microbes compared to soil environments, which provide protection against pathogens. We hypothesize that the addition of an inoculant can be used to decrease root borne disease incidence and severity. We will test the impact of inoculation with Root Shield (BioWorks, Victor, NY) which is OMRI certified organic and includes two different Trichoderma species on both yield and disease incidence.
To prevent issues with insect pests and control environmental conditions as part of our IPM plan we will erect netting around our systems largely preventing entry of large pollinating insects such as wild bees. In an urban environment these pollinators also are likely to be scarce, potentially decreasing yields substantially. Strawberries can be wind-pollinated, however there is some evidence that strawberry yields are increased with hand-pollination. We will test whether hand-pollination provides a significant benefit to strawberry yields.
Cooperators
- - Technical Advisor
Research
Location
The described trials will be carried out at Levo’s Hartford farm location on Homestead Avenue. This location will include a heated greenhouse as well as space outdoors for systems. Farm staff will be regularly available to maintain systems and quickly report any issues. A general training will be completed so that farm staff are all aware of the goals of the experiment and who to alert if any issues arise, such as a leak in a system or a disease issue.
System setup: For the first season, we will purchase starter strawberry plugs from the provider Nourse Farms located in Hadley, Massachusetts. These will be from the cultivars Albion and Seacrest. Each system will consist of a 27-gallon tote and will hold four strawberry plants to maintain the recommended 1 ft2 of space for each plant. Each plug will be transferred into 3-inch net pots and supported with a 2:1:1 mixture of perlite: peat: coco coir. Jack’s 8-10-26 Strawberry Part A Fertilizer (JR Peter’s) will be used along with Jack’s 15-0-0 Part B calcium nitrate fertilizer (JR Peter’s). The Part A fertilizer contains 10% of its nitrogen in ammonia form, which helps reduce solution pH. We will reduce the initial pH to 5.5 and maintain the pH between 5.5 and 6.0 with the addition of phosphoric acid. Daily checks on pH will be carried out, with accompanying acid additions as needed. Electrical conductivity (EC) will be measured daily and ¼ strength fertilizer or water will be added and mixed to maintain an EC between 800 and 1200 μS/cm2. Both pH and EC will be recorded. The water level will be maintained at a constant level by drilling a small hole just above the desired level.
Mother plant setup: For each cultivar, two additional Kratky systems with four plants each will be started. In both cases, the systems will be suspended at 4 feet in height. The strawberries will be allowed to grow out for a full spring and summer growing season. Cuttings will be taken in the early winter and placed into net pots with substrate. These cuttings in net pots will be misted three times a day until rooting occurs at approximately 4 weeks. These new plants will then be placed into production for season two. The initial mother plants will be left to continue to produce, and new mother plants will also be started.
Implementation of an integrated pest management (IPM) plan: Disease and pest management is critical for any farm operation and it is important that we plan for potential threats when we introduce a new crop. We have identified the following main potential issues.
- Potential Issue 1: Root rot caused by Pythium, Fusarium, and Rhizoctonia species can cause severe, even total, losses. To combat this, we will maintain high levels of oxygen in the nutrient solution, which helps to maintain root health and can decrease root rot severity. We will use an air stone to add supplemental oxygen and we will measure the dissolved oxygen level on a weekly basis. We will sanitize systems with 10% bleach prior to introduction of plants. The use of a Trichoderma species inoculant, as described below in Objective 2, may also provide protection against root rot.
- Potential Issue 2: Botrytis Fruit Rot attacks ripening or ripe fruit either pre- or post-harvest. To combat this issue we will immediately freeze or refrigerate strawberries to prevent its spread. We will apply sulfur-based fungicides if this disease begins to cause significant losses.
- Potential Issue 3: Anthracnose caused by Colletotrichum species is considered sporadic, but can cause up to complete loss when it infects the crown of a strawberry plant. Colletotrichum spores require free water to germinate, so we can prevent this disease by covering plants when we move them out of a greenhouse and preventing free water from being sprayed onto the shoots of plants. The Kratky system does not include overhead irrigation, decreasing the threat of Anthracnose.
- Disease/Pest Issue 4: Spider mites can cause significant losses and are a near certain issue in strawberry production. We will use a combination of the predator mites Neoseilulus californicus and Phytoseiulus persimilus to combat spider mites, with persimilus used in response to infection and N. californicus used as a preventative measure. If these are ineffective and we have a severe infection, we will apply insecticidal soap.
- Disease/Pest Issue 5: Thrips are another one of the most common pest issues. We will use the predatory miniature pirate bug Orius insidiosus to hunt down thrips. insidiosus also has substantial activity against other insect pests and so will be a useful preventative predator to place in our strawberry production.
Objective 2: Impact of Trichoderma inoculation and manual pollination on fruit yield and disease incidence
We will set up an experiment with two replicates consisting of two years each, overlapping for a total experimental time of three years. Data described below regarding disease incidence and yield will be collected continuously. Replicate one will be carried out in years 1 and 2, while replicate two will be completed in years 2 and 3. We will use two cultivar treatments consisting of Albion and Seacrest. Half of the systems will be hand-pollinated, with the other half serving as a control. Half of the systems will have plants inoculated with Trichoderma, again with the other half serving as a control. There will be 4 replicates for a total of 32 systems across eight treatment groups: (1) Albion, hand-pollinated, Trichoderma-inoculated, (2) Albion, hand pollinated, un-inoculated, (3) Albion, un-pollinated, Trichoderma-inoculated, (4) Albion, un-pollinated, un-inoculated, (5) Seacrest, hand-pollinated, Trichoderma-inoculated, (6) Seacrest, hand-pollinated, un-inoculated, (7) Seacrest, un-pollinated, Trichoderma-inoculated, (8) Seacrest, un-pollinated, un-inoculated.
Trichoderma isolates will be inoculated onto strawberry roots upon their placement into hydroponic systems. Root samples from each system of approximately 10g will be sent to the Connecticut Agricultural Experiment Station Valley Laboratory for fungal community analysis by technical advisor Dr. Nathaniel Westrick. This analysis will compare isolates with the initial Trichoderma inoculum to confirm or refute the establishment of the desired biocontrol Trichoderma strains. If these strains fail to establish, this will inform recommendations for farmers about when the use of these isolates is not appropriate.
Disease incidence will be recorded for systems in order to test the hypothesis that use of Trichoderma inoculation decreases disease incidence. We will scout for the presence of those diseases listed in the above Integrated Pest Management section. When symptoms are unclear, we will send pictures and samples as necessary to Dr. Nathaniel Westrick for assistance in diagnosis.
For those plants in hand-pollinated treatment groups, once flowers have matured, paintbrushes will be used to manually move flowers to promote their self-pollination. Manipulation of each flower will be done for a count of three seconds. The numbers of flowers formed and of fruit produced will be counted for each system. Incomplete pollination can cause malformed fruit. We will therefore count the number of malformed fruits and marketable fruits produced by each system. The weight of marketable fruits will be recorded for each system.
Statistical analysis
Fruit yield will be the main response variable for this experiment. We will study the impact of Trichoderma inoculation on fruit yield as well as disease incidence. We will study the impact of hand-pollination on fruit yield. We will also compare fruit yields for each of the cultivars Albion and Seacrest and the interactions between cultivars, Trichoderma inoculation, and hand-pollination as they impact fruit yields. R in RStudio will be used to carry out all statistical analyses and data visualization. We will run ANOVAs with Tukey post-hoc mean separation tests to test for significant differences between groups.
Data Management
EC, pH, fertilizer addition data, disease incidence data, pest incidence data fruit count data and fruit weight data will be maintained in Levo’s cloud data repository via the software Basecamp.
We started the first set of experiments using Kratky systems with the June-bearing strawberry varieties Flavorfest and Galletta that were available starting in August from Nourse Farms as plugs. The day-neutral varieties we initially proposed were not available, but we hope to begin trialing them next season. We set up 16 Kratky hydroponic systems of each, for a total of 32 systems in our greenhouse. Substantial leafy growth was observed in both cultivars between August and November.
Part of our production protocol that we are developing with this project is the vegetative propagation of daughter plants from runners. Ease of runner production is an important characteristic for us to include in our assessment of strawberry varieties because it determines how quickly we can build up our supply of seedlings without having to buy additional external plant material. External strawberry purchases increase our risk of introducing pathogens and add costs. We therefore hope to minimize this via propagation of daughter plants. Flavorfest plants did not produce runners between August and November 2025. Galletta plants produced several runners per system. We were able to pot 41 Galletta runners and successfully separated them into daughter plants that survived on their own. This successful daughter plant generation protocol can be used in the next growing seasons. We expect that spring weather conditions will promote runner growth from Flavorfest as well.
The delay in seedling plug availability until August caused us to shift our initial focus towards developing the overwintering protocol for our strawberry plants. Plant yields are improved if they experience a cold dormancy period. In the first week of November, we trimmed the runners off of all the plants and cut back any discolored leaf tissue. These plants are currently overwintering in the greenhouse without heat so that they experience sub-freezing temperatures required for dormancy.
The biggest challenge with overwintering them in the hydroponic systems is protecting the roots. We have seen some root damage that appears to be caused by the cold. We expect that the plants will be able to overcome this damage in the spring once temperatures increase. We have also attempted overwintering the Galletta daughter plants by placing them outdoors, covered in a 3:1 mixture of coco coir: perlite. We will compare the survival rate and health of plants that were overwintered in the Kratky systems in a greenhouse versus plants overwintered in media outdoors. We hypothesize that overwintering in media may improve results as this provides increased root protection. On the other hand, overwintering outdoors requires additional precision maintenance as adequate moisture must be carefully maintained in the media. Data that we gain from this experiment will inform our protocols for growth of strawberries in simplified hydroponics.