Cumulative total yield by harvest date for 15 strawberry cultivars at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA, for the 2023 and 2024 harvests. Each panel includes two graphs: white-on-black (white) mulch on the left and black mulch on the right. Harvests were conducted once or twice weekly from late April to June, using four representative plants per subplot. Lines show the progression of total yield over time for each cultivar.
Cumulative total yield by harvest date for 15 strawberry cultivars at the Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA, for the 2024 harvest. Information at MEIGS in 2023 was not included due to the overall low yield from frost damage. Each panel includes two graphs: white-on-black (white) mulch on the left and black mulch on the right. Harvests were conducted once or twice weekly from late April to June, using four representative plants per subplot. Lines show the progression of total yield over time for each cultivar.
Daily average soil temperature under black and white-on-black (white) plastic mulch and air temperature at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA, and Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA. Data are shown for the coldest periods of the Winters 2022–23 and 2023–24. Black and white plastic soil temperatures represent averages recorded under each mulch using HOBO® data loggers, while air temperature data were retrieved from the Vincennes 5NE (SWPAC) and Lafayette 8S (MEIGS) weather stations via the Midwestern Regional Climate Center’s cli-MATE tool.
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Strawberries (Fragaria ×ananassa) are commonly grown on fruit and vegetable farms in the lower Midwest. Farmers are interested in exploring plasticulture strawberry production with more than 1 year of harvest to offset the high cost of planting materials. However, key questions remain, including the selection of plastic mulch color and cultivar. This study evaluated 15 June-bearing strawberry cultivars for yield, ripening pattern, and runner production in a 2-year plasticulture system using white and black plastic mulches at two locations—southern and northern Indiana—from late Summer 2022 through Summer 2024. Across cultivars, strawberries grown on black plastic mulch generally produced higher yields than those on white. Plants grown on black plastic accumulated less runner biomass in the summer, which could lessen the labor required for runner removal. However, black plastic mulch may advance the onset of flowering, potentially increasing the risk of spring frost damage. Additionally, plants established on black plastic mulch, when subjected to extreme cold weather and without frost protection in the winter, may have been more adversely affected, resulting in reduced yield and plant survival. When comparing cultivars, Flavorfest and Chandler consistently produced the highest yields at both locations. However, the small fruit size of ‘Chandler’, particularly in the second year, may limit its suitability for the 2-year plasticulture system. ‘AC Valley Sunset’ exhibited low survival and yields, indicating it was not well-suited for this production system. Likewise, early-season cultivars such as ‘Sweet Charlie’ and ‘Sensation’ may not perform well in the Midwest due to the high risk of spring frost damage.
Strawberries are commonly grown on fruit and vegetable farms in the lower Midwest region of the United States (Samtani et al. 2019), where they are marketed directly to consumers through u-pick operations, farm stands, and farmers’ markets. Although the total acreage of strawberry production in the region is relatively small, strawberries are often among the highest-value cash crops on these farms and serve as a strong draw for consumers to visit farms and farm stands. Traditionally, June-bearing strawberries are grown in a matted-row system in the region. In this system, bare-root strawberry plants are transplanted into bare ground in April or May (Ellis et al. 2006). Plants develop runners that establish and become daughter plants to fill the rows. Flower clusters developed in the first year are pruned. Strawberries are first harvested the following year and continue to produce for two to three seasons before replanting (Ellis et al. 2006).
The annual plasticulture system for June-bearing cultivars was introduced in the lower Midwest in the early 2000s (Hokanson and Finn 2000). Around the same time, the use of plug plants became widely adopted. In this system, June-bearing strawberry plugs are transplanted into plastic mulch–covered beds in late August to middle September (Demchak et al. 2005). Strawberries are harvested the following spring, and the crop is ended after the harvest. Compared with the matted-row system, the plasticulture system provides better in-row weed control, offers a shorter interval between planting and harvest, produces cleaner fruit, and increases the ease of harvest (Black et al. 2002; Stevens et al. 2007). Compared with bare-root plants, using plug plants reduces transplanting labor and improves establishment and initial survival rates (Durner et al. 2002). Additionally, plug plants of most June-bearing cultivars do not develop flower clusters in the first year, eliminating the need for flower cluster removal.
Although the annual plasticulture of June-bearing cultivars and plug transplant technologies have been introduced in the lower Midwest for over 20 years, their adoption has remained limited. One major barrier is the risk of low yields, particularly when fall transplanting is delayed (Demchak et al. 2005), as the daily average temperature can drop below 50 °F in October. Additionally, plasticulture strawberry production in the lower Midwest is highly susceptible to spring frost damage, which can significantly reduce yields unless effective frost protection measures are implemented. High establishment costs also present a challenge: the number of plants required for plasticulture is more than twice that of a traditional matted row system (Stevens et al. 2011). Additionally, the cost of plug plants has increased by nearly 40% over the past 5 years, and the limited availability of clean, disease-free plants further constrains the broader adoption of annual plasticulture systems in the lower Midwest.
Facing these challenges, farmers have shown growing interest in maintaining the same strawberry plants on plastic-mulched beds for multiple years rather than replanting annually (North Central Sustainable Agriculture Research and Education 2025). In this multiyear system, plants are often mowed back to crown level after the first spring harvest and then maintained through summer, fall, and winter for another harvest the following spring (Weber 2021). Compared with the annual plasticulture system, the extended crop season introduces new management challenges. One of them is runner management. During summer, strawberry plants respond to longer daylength and warmer temperatures by producing runners that can extend several feet from the mother plant. When the nodes of the runners contact moist soil, they develop roots and leaves, forming new daughter plants within 2 to 3 weeks. If not controlled, a single mother plant can produce up to 100 daughter plants in one season (Strand 2008). Runners are undesirable in the plasticulture system because they divert water and nutrients away from the mother plant. Once established, daughter plants often root in the aisles between rows, where they interfere with crop management and harvest in the following seasons. Farmers typically rely on manual removal of runners, a task that requires considerable labor.
Despite the challenges of the multiyear plasticulture system, farmers continue to experiment with it, underscoring the need for research-based recommendations. Key uncertainties include mulch color and cultivar selection. Plastic mulch modifies the crop microclimate, which, depending on weather conditions, can either reduce or intensify environmental stresses (Kasirajan and Ngouajio 2012; Tarara 2000). Although the effects of black and white mulch colors on strawberry performance have been studied across various regions (Dash et al. 2023; Himelrick et al. 1993; Johnson and Fennimore 2005), their impacts have not been examined in a 2-year June-bearing plasticulture system under the conditions of the lower Midwest. Likewise, most strawberry cultivars were developed for annual plasticulture or matted-row systems, leaving their performance in multiyear plasticulture largely unknown. To address these gaps, we evaluated 15 June-bearing strawberry cultivars grown on white-on-black and black plastic mulches in a 2-year plasticulture production system in the lower Midwest.
The experiments were conducted at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA (lat. 38.7384°N, long. 87.4845°W), and the Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA (lat. 40.2911°N, long. 86.8843°W), beginning in late Summer 2022 and concluding in Summer 2024. These two locations were located in southern and northern Indiana with different weather conditions (Table 1) and soil types. At SWPAC, the soil was an Alvin fine sandy loam (coarse-loamy, mixed, superactive, mesic Typic Hapludalfs) with 1.8% organic matter and pH 5.8. At MEIGS, the soil was a combination of Toronto-Millbrook silt loam (fine-silty, mixed, superactive, mesic Udollic Epiaqualfs) and Drummer silty clay loam (fine-silty, mixed, superactive, mesic Typic Endoaquolls) with 2.9% organic matter and pH 6.3.
The experiment was a split-plot design with a factorial treatment arrangement consisting of two polyethylene (plastic) mulch colors as the main plot factor and 15 June-bearing strawberry cultivars as the subplot factor. The experiment had three replications, with the main and subplot factors randomly assigned within each replication at each location. Plastic mulch colors were white-on-black (hereafter referred to as “white”) and black (both 1.25 mil, 4 ft wide; Harris Seeds, Rochester, NY, USA). Plug plants were used for all cultivars evaluated. The cultivar names, their origins, and the plant sources are listed in Table 2.
Raised beds (4 inches tall, 30 inches wide, 6 ft apart on-center) were formed and covered with plastic mulch. Two drip tapes with 12-inch emitter spacing were installed beneath the mulch, spaced ∼1 ft apart. The beds were prepared using plastic mulch layers (SWPAC: model 90 mulch layer; Mechanical Transplanter Company, Holland, MI, USA; and MEIGS: model 2550 series II; Rain-Flo Irrigation, East Earl, PA, USA) before transplanting. On 7 Sep 2022 (SWPAC) and 8 Sep 2022 (MEIGS) strawberry plugs were transplanted into the raised beds arranged into two staggered rows, with 12-inch spacing between rows and 12-inch spacing between plants within each row. Each subplot consisted of 12 plants at SWPAC and 10 plants at MEIGS. Runners were removed by pinching before transplanting.
At SWPAC, the field received a preplant application of 60 lb/acre of nitrogen (N) from urea (46N–0P–0K; Knox Fertilizer Co., Knox, IN, USA), 60 lb/acre of potassium (K) from potash (0N–0P–60K; Knox Fertilizer Co.), 100 lb/acre of pelletized lime, and 1 lb/acre of boron (B) (boron 15%; Winfield Solutions LLC, St. Paul, MN). During Springs 2023 and 2024, the plants were fertigated with a liquid fertilizer (4N–0P–8K; Brandt Consolidated, Inc., Springfield, IL, USA), providing ∼40 lb/acre of nitrogen each spring. At MEIGS, preplant fertilization was limited to 76 lb/acre of N from urea. Fungicides were applied regularly in the spring to control foliar diseases following recommendations from the Midwest Fruit Pest Management Guide (Beckerman et al. 2021).
Floating row covers with 1.5 oz/yd2 thickness (Agribon AG-50; Tarps America, Ponchatoula, LA, USA) were used for winter protection in both locations from Dec 2022 to Feb 2023. Floating row covers were not used in the 2023–24 winter. At SWPAC, row covers were deployed in Spring 2024 locations frost protection; at MEIGS, a sprinkler system installed in Fall 2023 was operated the following spring. At both locations, frost protection was implemented when forecast minimum temperatures fell below 35 °F during the flowering period. No spring frost protection was applied in Spring 2023.
Fruits were harvested when fully ripe or when more than 50% of the surface had turned pink. Harvests were conducted once or twice a week from four representative plants from each subplot. At SWPAC, harvest lasted from 9 May to 13 Jun in 2023 and from 26 Apr to 29 May in 2024. At MEIGS, it lasted from 26 May to 9 Jun in 2023 and from 6 May to 4 Jun in 2024. For each subplot, fruit number and total weight were recorded. Average marketable fruit size was calculated using fruits weighing ≥8 g and showing no visible biotic or abiotic damage.
Runner growth was assessed in June and Aug 2023 at both locations. These were counted and removed from four representative plants per subplot in the June runner assessment. The average number of runners per plant was calculated. Runners were then allowed to grow freely through the summer. By late August, most runners were interlaced and had established daughter plants. At that point, all runners were detached from the mother plants in each subplot, and their biomass weight was recorded.
Plant stand counts were recorded in Aug 2023 and Apr 2024 at both locations. The survival percentage of strawberry plants was calculated by comparing the number of plants present in each subplot to the original number transplanted.
At each location, four HOBO® U23 Pro v2 external temperature data loggers (HOBO Data Loggers, Bourne, MA, USA) were installed in the raised beds at about a 3- to 4-inch depth, with two in beds covered with white plastic mulch and two in beds covered with black plastic mulch. Each data logger sensor was placed directly in contact with the soil under the plastic and set to collect soil temperature once every hour from Sep 2022 until Jun 2024. Ambient environmental conditions were retrieved from the Vincennes 5NE (SWPAC) and Lafayette 8S (MEIGS) weather stations via the cli-MATE: Midwest Regional Climate Center application tools environment (Midwest Regional Climate Center 2025).
All data were analyzed using R software (RStudio®; PBC, Boston, MA, USA). Normality was assessed using Q-Q plots. Percentage and weight data were analyzed using linear models, while count data were analyzed using generalized linear models with Poisson or negative binomial distributions, depending on the presence of overdispersion. When needed, data were transformed to meet model assumptions; however, back-transformed means are presented under “Results.”
The data were analyzed separately by location, as preliminary analysis indicated a significant effect of location on most variables. The only exception was the number of runners evaluated in June, for which no significant location effect was detected. Analysis of variance was used to test for main effects and interactions. Plastic mulch color, cultivar, and their interaction were included as fixed effects. When significant effects were detected (P ≤ 0.05), means were separated using Tukey’s honestly significant difference test.
The effects of mulch color and cultivar on total yield and marketable fruit size varied by year and location, but no interaction between the two factors was detected.
At SWPAC in 2023, plants grown on black plastic mulch produced significantly higher yields than those on white plastic mulch (Table 3). At MEIGS, no significant difference was observed in 2023, likely due to extensive frost damage. In 2024. the trend reversed at SWPAC, with white plastic mulch yielding more than black. While at MEIGS, yields were higher on black plastic mulch than white. When combining yield data from both years, black plastic mulch resulted in significantly higher total yields than white mulch at MEIGS. The opposing trends of the 2 years’ harvest at SWPAC led to no significant difference in cumulative yields between the two mulch types.
Regardless of harvest year, the average marketable fruit size was similar between mulch types at SWPAC. In contrast, at MEIGS, marketable fruits from plants grown on black plastic mulch were significantly larger than those grown on white plastic mulch.
Across cultivars, plants grown on black plastic mulch ripened earlier than those on white plastic mulch at SWPAC in 2023 and at MEIGS in 2024 (Figs. 1 and 2). At SWPAC in 2023, by the second harvest on 12 May, yields on black plastic mulch exceeded 0.1 lb/plant for most cultivars except ‘Keepsake’ and ‘AC Valley Sunset.’ On white plastic mulch, comparable yields for most cultivars were not reached until about 7 d later. A similar trend of earlier harvest on black plastic mulch was also observed at MEIGS in 2024. However, this pattern was not evident during the second harvest season at SWPAC in 2024.
Citation: HortTechnology 35, 6; 10.21273/HORTTECH05781-25
Citation: HortTechnology 35, 6; 10.21273/HORTTECH05781-25
At SWPAC, ‘Camarosa’, ‘Camino Real’, ‘Chandler’, and ‘Flavorfest’ each produced more than 0.8 lb/plant in 2023, and ‘Flavorfest’, ‘Darselect’, ‘Camino Real’, ‘Merced’, and ‘Yambu’ yielded over 1.2 lb/plant in 2024 (Table 4). When harvests from both years were combined, four cultivars—Flavorfest, Camino Real, Darselect, and Merced—exceeded a total of 2 lb/plant. At MEIGS, all cultivars yielded below 0.5 lb/plant in 2023. In 2024, ‘Cabot’, ‘Camino Real’, ‘Chandler’, and ‘Flavorfest’ each yielded more than 1 lb/plant. Combining both years’ yield, ‘Cabot’, ‘Flavorfest’, ‘Chandler’, and ‘Camarosa’ yielded above 1.3 lb/plant.
Overall, fruits were smaller in the second-year harvest compared with the first year at both locations, except ‘AC Valley Sunset’ (Table 5). Among the cultivars, Fronteras and Merced consistently produced larger fruit, while ‘Sweet Charlie’ and ‘Chandler’ stood out for their smaller fruit size. Across locations and years, ‘Sweet Charlie’ consistently ripened the earliest. ‘Galletta’, ‘Merced’, and ‘Sensation’ were also relatively early-ripening, while ‘AC Valley Sunset’, ‘Cabot’, and ‘Keepsake’ were among the latest to ripen.
Runner growth was observed at the onset of harvest, and a large number of runners developed and established over the summer by late August. No significant interaction between mulch color and cultivar was found for runner number in June or for runner biomass in late August evaluations. However, both mulch color and cultivar had significant effects on runner growth.
Plants developed a similar number of runners in Jun 2023, regardless of whether they were grown on white or black plastic mulch (Table 6). However, in Aug 2023, the runner biomass was significantly greater in plants grown on white mulch compared with those grown on black mulch, a trend observed across both locations.
Among cultivars, ‘Flavorfest’ produced the fewest runners in June, pooled across both locations. ‘Darselect’, ‘Yambu’, and ‘Cabot’ also produced fewer runners compared with the other cultivars. In contrast, ‘Sweet Charlie’ produced the greatest number of runners, followed by ‘Sensation’, ‘Merced’, ‘Camarosa’, and ‘Chandler’. By late August, ‘Sensation’, ‘Camarosa’, ‘Fronteras’, and ‘Camino Real’ produced the greatest runner biomass at both locations. ‘Cabot’ and ‘AC Valley Sunset’ produced the least runner biomass. Interestingly, cultivars such as ‘Flavorfest’, ‘Darselect’, and ‘Yambu’, which had relatively few runners in June, produced substantial runner biomass by late August.
Plant survival as a response to plastic mulch color and cultivar varied by year and location; however, no interaction between the two factors was detected.
Plant survival was similar across plastic mulch colors at both locations in Aug 2023 (Table 7). However, in Apr 2024, plant survival at SWPAC was lower on black plastic than on white plastic mulch. At MEIGS, survival rates were higher compared with SWPAC, with no significant difference observed between mulch colors.
‘AC Valley Sunset’ consistently showed the lowest survival rates across locations. Additionally, ‘Camino Real’ and ‘Ruby June’ also had relatively low survival rates at SWPAC. At MEIGS, ‘Keepsake’ and ‘Ruby June’ exhibited lower survival compared with other cultivars besides ‘AC Valley Sunset’.
Soil temperatures recorded at 3- to 4-inch depth were consistently higher under black plastic mulch compared with white. The differences ranged from 0.8 to 3.6 °F at SWPAC and 1.2 to 4.7 °F at MEIGS, depending on the season (Table 1).
The coldest period of the 2022–23 season occurred between 23 and 31 Dec 2022, at both locations, with the lowest daily average air temperatures reaching −0.5 °F at SWPAC and −1.5 °F at MEIGS (Fig. 3). Row covers were applied during this period, likely moderating soil heat gain and loss, thereby minimizing differences in soil temperature among mulch colors. The lowest daily average soil temperatures recorded were 33 °F under both plastic colors at SWPAC and 29.5 °F under white plastic and 31 °F under black plastic at MEIGS. In Winter 2023–24, the coldest period occurred from 14 to 24 Jan 2024 at both locations, with the lowest daily average air temperatures reaching 3 °F at SWPAC and −6 °F at MEIGS. During the second winter, neither location used row covers during the coldest period. The lowest soil daily average temperatures at SWPAC dropped to 27.7 °F under white plastic and 29.3 °F under black plastic. At MEIGS, due to snow protection, the values were similar to those observed the previous year, with 31.1 °F under white plastic and 30.2 °F under black plastic.
Citation: HortTechnology 35, 6; 10.21273/HORTTECH05781-25
The adoption of annual June-bearing plasticulture strawberry production in the lower Midwest offers benefits, but the high upfront costs, combined with weather-related risks, can make a single season of production economically unjustifiable. To recoup these costs, growers are increasingly interested in extending plasticulture systems for multiyear harvesting. However, extending production into a second year introduces additional challenges. In this experiment, we evaluated the influence of mulch color and cultivar selection on June-bearing strawberry production in a 2-year plasticulture system, with the goal of supporting growers in their decision-making.
Black plastic mulch increases soil temperature relative to bare ground due to its thermal and radiation properties and is therefore the most widely used mulch for warm-season vegetable production worldwide. In contrast, white plastic reflects much of the visible light and maintains cooler soil temperatures than black plastic, making it better suited for heat-sensitive crops or for production in warmer climates (Kasirajan and Ngouajio 2012; Tarara 2000). In the 2-year plasticulture system, the wide seasonal variation means that multiple environmental factors must be considered when selecting plastic mulch color.
Spring yield potential of the strawberry production system evaluated in the experiment depends largely on crown growth and flower bud initiation during the preceding fall (Fernandez 2001). Crown growth requires temperatures of at least 50 °F, while flower initiation occurs under short daylengths when temperatures remain above 60 °F (Strand 2008). In Indiana, daily temperatures often fall below these thresholds by October or November, depending on locations (Midwest Regional Climate Center 2025). Consequently, maintaining a warmer environment for a longer period in the fall with black plastic mulch can promote crown growth and flower initiation, potentially enhancing yields the following spring. This assumption was supported by higher yield from plants grown on black plastic mulch compared with white plastic mulch in Spring 2023 at SWPAC, and in Spring 2024 at MEIGS.
Interestingly, the yield trend reversed in the second spring at SWPAC, with plants on white plastic mulch producing higher yields than those on black plastic. In addition to lower yields, plants grown on black plastic had a lower survival rate compared with plants grown on white plastic in the Apr 2024 assessment. Since survival rates were similar between mulch colors in the Aug 2023 assessment, the difference likely occurred during the Winter 2023–24. A potential explanation for the poorer performance of plants on black plastic is that freezing temperatures during the winter may have killed or injured some plants.
Winter protection with row covers is recommended in regions where temperatures can drop below 10 °F (Poling 2016), a threshold frequently reached during Indiana winters. Row covers were not used during the second winter, intentionally to evaluate the winterhardiness of different strawberry cultivars. Consequently, soil temperatures at a 3- to 4-inch depth dropped below 30 °F at SWPAC. Given that air temperatures had fallen into the single digits, branch crowns located near the soil surface likely experienced lower temperatures than those recorded at the 4-inch depth.
Strawberries grown in temperate climates have to survive the cold winters. Critical crown temperatures are estimated to range from about 10 to – 4 °F (Turner et al. 1993), and crown injury was reported at 16 °F (Maughan et al. 2015). The critical temperature threshold is likely higher in plants that are less acclimated to winter conditions (Harris 1973). Factors such as duration of exposure to freezing temperatures (Linde Òn et al. 2002) and different cold hardiness among cultivars (Nestby and Bjørgum 1999) also influence critical temperature thresholds.
In this study, although minimum soil temperatures were slightly higher under black plastic than under white plastic mulch, plants on black plastic were likely less acclimated to low temperatures due to generally warmer soil conditions, making them more vulnerable to extreme cold events. In addition, previous field observations have noted that the depth of crown placement in the soil affects plants’ overwintering capability (Turner et al. 1993). Daughter plants seem to overwinter more successfully than mother plants (Shokaeva 2008). This is because crowns of the daughter plants are well buried in the soil, while the newest branch crown grown on the mother plants tends to be raised slightly above the original crowns. Strawberries grown on black plastic mulch are likely to develop more branch crowns than those grown on white plastic mulch. As a result, these plants may be more vulnerable to winter injury, particularly during the second winter. A similar trend was reported in a plasticulture strawberry experiment conducted in Geneva, NY, where low survival rates were observed for plants grown on black plastic mulch after the second winter (Weber 2021).
In the spring, root growth resumes once soil temperatures rise above 45 °F. As temperatures continue to rise, previously initiated flower clusters develop, and plants enter the flowering stage. During this period, flowers are highly vulnerable to low temperatures. The critical temperature thresholds are generally considered to be 30 °F for open flowers, 26 °F for popcorn-stage flowers, and 22 °F for tight floral buds (Poling 2008). In Indiana, these threshold temperatures frequently occur in March and April, coinciding with the flowering of plasticulture strawberries. At the two research locations, the average last spring frost (32 °F or lower) ranged from 15 to 22 Apr at MEIGS and from 3 to 9 Apr at SWPAC. However, frost events can still occur as late as 13 May at MEIGS and 23 Apr at SWPAC (Indiana State Climate Office 2025). Exposure to frost can damage flowers, resulting in small or misshapen fruit. In severe cases, it may cause flower death and complete yield loss (Ki and Warmund 1992). To ensure good yields, farmers must remain vigilant and be prepared to implement frost protection measures in spring. At MEIGS in Spring 2023, minimum temperatures dropped below 30 °F on 18 and 31 Mar, with additional frost events on 2, 18, and 24 Apr. Because frost protection practices were not implemented during these events, severe yield losses occurred in the first-year harvest at MEIGS. At SWPAC, minimum temperatures fell into the lower 20s °F from 18 to 20 Mar, with another frost event on 2 Apr 2023. No frost protection measures were applied there either, which may also have contributed to lower yields in 2023 compared with previous strawberry yields with plasticulture system (Wenjing G, unpublished data).
A delay of about 1 week in fruit ripening was observed on plants grown on white plastic mulch compared with those on black plastic mulch in Spring 2023 at SWPAC and Spring 2024 at MEIGS. This delay is likely related to soil temperature differences caused by mulch color. At a 4-inch depth, soil temperatures under black plastic were 1.6 to 4.7 °F higher than those under white plastic mulch in the two springs. The warmer soil promoted faster plant growth, resulting in slightly earlier harvests with black plastic mulch. Earlier growth also advanced the onset of flowering, which may have increased the risk of frost damage. However, because the timing of spring frost events is highly unpredictable, mulch color alone is not a reliable strategy for preventing frost injury.
Unlike annual plasticulture strawberry production in the Southeast, where plants are ended after the first spring harvest (Hoffmann et al. 2024). In the 2-year system, we mowed the plants after harvest and allowed them to regrow over the summer. Under long daylengths and high temperatures, plants naturally allocate energy toward producing runners and establishing daughter plants (Leshem and Koller 1965), which is undesirable in the 2-year system. Strawberries grow best at temperatures between 52 and 77 °F (Wang and Camp 2000), and runner growth can tolerate higher temperatures (Kadir et al. 2006). During the summer, field temperatures often exceed these optimum ranges, particularly with black plastic mulch, which was shown to increase soil temperatures for more than 3 °F compared with soil temperatures under white plastic mulch. This additional heat stress likely reduced runner biomass accumulation in plants grown on black plastic. Additionally, greater light reflectance from white plastic may stimulate vegetative growth, potentially contributing to the higher runner biomass observed on white mulch compared with black. Because runner removal is a labor-intensive task, the increased runner growth associated with white plastic in the 2-year plasticulture system may lead to greater labor demands for managing the system in the summer.
In recent decades, many new strawberry cultivars have been developed alongside rapidly evolving production systems (Hokanson and Finn 2000). The performance of these cultivars demonstrates strong genotype-by-environment interactions, underscoring the importance of breeding and cultivar selection tailored to regional climatic conditions and production practices. In the lower Midwest, strawberry production often relies on cultivars developed in other regions. Thus, 15 short-day cultivars with diverse genetic backgrounds were evaluated in this 2-year plasticulture strawberry system.
‘Flavorfest’ was among the top-yielding cultivars at both locations, a trend consistent with previous annual plasticulture strawberry evaluations in the region (Wenjing G, unpublished data). High yield of ‘Flavorfest’ was also observed in an annual plasticulture strawberry trial conducted in Geneva, NY (Weber 2021). Compared with the widely grown plasticulture cultivar Chandler, Flavorfest produced smaller yields early in the season but reached comparable or higher yields toward the end of harvest. This ripening pattern aligns with its previous description as a midseason cultivar with an extended harvest period (Lewers et al. 2017). At both locations, ‘Flavorfest’ consistently produced the fewest runners in the mid-June evaluation. However, in Aug 2023, its runner biomass ranked midrange among cultivars. This suggests that although ‘Flavorfest’ produces fewer runners, the vigorous growth of its runners and daughter plants may not necessarily reduce the labor required for runner removal.
‘Chandler’, ‘Camarosa’, and ‘Camino Real’ are widely adapted plasticulture cultivars in the Southeast (Poling 2016) and continue to deliver strong yields in the 2-year plasticulture system. However, all three cultivars produced abundant runners during the summer, suggesting that their use in a 2-year system may require increased labor for runner removal. Despite its consistently high productivity, ‘Chandler’ is known for producing relatively small fruit (Guan et al. 2022), a trend also confirmed in the current study. Because fruit size generally declines in the second year compared with the first, the small fruit size of ‘Chandler’ may limit its suitability for 2-year production.
‘Darselect,’ ‘Merced,’ ‘Yambu’, and ‘Cabot’ also demonstrated strong yield potential at one or both locations. Both ‘Merced’ and ‘Cabot’ were notable for producing large fruit in at least 1 year. Additionally, ‘Yambu’, ‘Darselect’, and ‘Cabot’ produced relatively few runners, and ‘Cabot’ accumulated less runner biomass by the end of the season, suggesting its potential to reduce labor requirements for runner removal.
Although this study was not specifically designed to evaluate cold hardiness, the low-temperature stress experienced during the winters—particularly Winter 2023–24 at SWPAC—provided an opportunity to assess cultivar performance under adverse weather conditions. ‘AC Valley Sunset’ exhibited the lowest survival, with only 21% of plants surviving at SWPAC and 55% at MEIGS in Spring 2024. Similar poor winter performance of this cultivar has been noted previously in Indiana (Stephen LM, unpublished data). When both seasons’ yields were combined, ‘AC Valley Sunset’ ranked the lowest at SWPAC and the third lowest-yielding cultivar at MEIGS. Despite producing very large fruit and exhibiting the late-season ripening pattern previously described (Jamieson et al. 2010), our results indicate that ‘AC Valley Sunset’ is not suitable for the 2-year plasticulture production system. After the second winter, ‘Ruby June’ also showed relatively low survival, with 68% surviving at SWPAC. In addition to ‘AC Valley Sunset’, ‘Ruby June’ and ‘Keepsake’ produced comparatively low yields at SWPAC. Although cold hardiness information is available for some strawberry cultivars (Turhan et al. 2012; Zareei et al. 2021), such data are often limited or unavailable for newly developed ones. Furthermore, few studies have compared commonly grown cultivars bred for different production systems under the same conditions. Given the importance of cold hardiness in the 2-year plasticulture system in the lower Midwest, dedicated studies evaluating cultivars with diverse genetic backgrounds are needed to support the adaptation and optimization of this production system in the region.
At MEIGS, ‘Sweet Charlie’ and ‘Sensation’ had the lowest yields. Both cultivars, bred in Florida (Howard 1994; Whitaker et al. 2015), are known for their early ripening in plasticulture systems (Guan et al. 2022; Poling 2016). Our results suggest that these cultivars may not be well suited to plasticulture production in the Midwest, where spring frost events commonly occur in March and April.
Results from this project highlight that multiple factors must be weighed when selecting mulch colors for the two-season plasticulture system. Because of the warming effect, black plastic mulch generally produced higher yields and reduced summer runner production, potentially lowering labor requirements for runner removal. However, its warming effect in spring can stimulate early plant growth, increasing the need for frost protection. Plants grown on black plastic mulch may also be more vulnerable to winter freezing damage, further elevating the need for winter protection. In contrast, white plastic mulch provides a cooler environment during harvest, which can be particularly advantageous for u-pick operations where ripened fruit may remain in the field. Cooler conditions help preserve fruit quality for longer periods on hot days, although the lower yield potential associated with white mulch should be taken into account. Finally, practical considerations such as the availability and cost of mulch materials should also guide decision-marking.
Multiple June-bearing strawberry cultivars with diverse genetic backgrounds were evaluated in this study. ‘Flavorfest’ and ‘Chandler’ consistently produced high yields at both locations; however, the smaller fruit size, particularly in the second year, may limit the suitability of ‘Chandler’ for the two-season system. ‘AC Valley Sunset’ showed low survival and yields, suggesting it is not well suited for this production system. Early-season cultivars such as ‘Sweet Charlie’ and ‘Sensation’ carry a high risk of spring frost damage, which also limits their potential. This study did not assess fruit quality or cultivar performance under disease pressure, both of which are important factors to consider when selecting cultivars for local production. As farmers increasingly adopt the 2-year plasticulture system in the region, additional studies on cold hardiness, nutrient and weed management, and integrated pest management strategies are needed to optimize the production system.
Cumulative total yield by harvest date for 15 strawberry cultivars at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA, for the 2023 and 2024 harvests. Each panel includes two graphs: white-on-black (white) mulch on the left and black mulch on the right. Harvests were conducted once or twice weekly from late April to June, using four representative plants per subplot. Lines show the progression of total yield over time for each cultivar.
Cumulative total yield by harvest date for 15 strawberry cultivars at the Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA, for the 2024 harvest. Information at MEIGS in 2023 was not included due to the overall low yield from frost damage. Each panel includes two graphs: white-on-black (white) mulch on the left and black mulch on the right. Harvests were conducted once or twice weekly from late April to June, using four representative plants per subplot. Lines show the progression of total yield over time for each cultivar.
Daily average soil temperature under black and white-on-black (white) plastic mulch and air temperature at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA, and Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA. Data are shown for the coldest periods of the Winters 2022–23 and 2023–24. Black and white plastic soil temperatures represent averages recorded under each mulch using HOBO® data loggers, while air temperature data were retrieved from the Vincennes 5NE (SWPAC) and Lafayette 8S (MEIGS) weather stations via the Midwestern Regional Climate Center’s cli-MATE tool.
Contributor Notes
We thank Emmanuel Cooper, Josué Cerritos, Celia Corado, Carlos López, Lidysce Mata, Megan Low, Vera Vuković, Dean Haseman, Dennis Nowaskie, the Southwest Purdue Agricultural Center summer workers, Chloe Henscheid, and Paul Howard for assisting with this research.
This work was supported by the US Department of Agriculture (USDA) through the Specialty Crops Block Grant Program (Indiana State Department of Agriculture), the National Institute of Food and Agriculture (NIFA) under Award 2021-38640-34714 (North Central Region Sustainable Agriculture Research and Education program) Project LNC21-454, and the USDA-NIFA Hatch Project 7000862. No conflicts of interest have been declared.
W.G. is the corresponding author. E-mail: guan40@purdue.edu.
Cumulative total yield by harvest date for 15 strawberry cultivars at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA, for the 2023 and 2024 harvests. Each panel includes two graphs: white-on-black (white) mulch on the left and black mulch on the right. Harvests were conducted once or twice weekly from late April to June, using four representative plants per subplot. Lines show the progression of total yield over time for each cultivar.
Cumulative total yield by harvest date for 15 strawberry cultivars at the Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA, for the 2024 harvest. Information at MEIGS in 2023 was not included due to the overall low yield from frost damage. Each panel includes two graphs: white-on-black (white) mulch on the left and black mulch on the right. Harvests were conducted once or twice weekly from late April to June, using four representative plants per subplot. Lines show the progression of total yield over time for each cultivar.
Daily average soil temperature under black and white-on-black (white) plastic mulch and air temperature at the Southwest Purdue Agricultural Center (SWPAC), Vincennes, IN, USA, and Meigs Horticulture Research Farm (MEIGS), Lafayette, IN, USA. Data are shown for the coldest periods of the Winters 2022–23 and 2023–24. Black and white plastic soil temperatures represent averages recorded under each mulch using HOBO® data loggers, while air temperature data were retrieved from the Vincennes 5NE (SWPAC) and Lafayette 8S (MEIGS) weather stations via the Midwestern Regional Climate Center’s cli-MATE tool.
