Evaluating Sorrel (Hibiscus sabdariffa) Varieties for Production in Florida

Cooperators

Year 1:
University of Florida Institute of Food and Agriculture Sciences (UF/IFAS) Extension

Bountiful Farms

Dirty Dog Organics

University of the Virgin Islands Agricultural Experiment Station (UVI AES)

Year 2:
Dirty Dog Organics replaced with Whispering Oaks Farm. Other partners remained the same.

Objective 1: To evaluate the production of sorrel in Florida.

Trial History

Bountiful Farms: In mid-July of Year 1 we noticed symptoms of green wilt in the ‘Black’ variety followed by some chlorosis, leaf drop and eventual death of the plant, if not removed when symptoms become visible. A sample was submitted to the UF/IFAS Plant Clinic in Apopka for diagnosis. The results determined that the cause of the wilt was Phytophthora. As the number of plants with these symptoms and white cottony mycelium at the base continued to progress throughout the field, we submitted another sample to the UF/IFAS Disease Diagnostic Lab in Gainesville. The results showed they were affected by a combination of Southern Blight (Sclerotium rolfsii) and Fusarium Crown and Stem Rot (Fusarium sp./spp.). By the end of August, of the plants from which we were collecting data, we had 0.08% of the ‘Black’; 50% of the ‘Local’ and ‘Day Neutral’; and 42% of the ‘Festival’ varieties remaining. By end of September only 20 plants remained in the entire field, so we decided to officially close out the season at Bountiful Farms on October 7^th as there were too many missing data points on the plant height measurements.

During the period the crop was in the ground, June to November, grasshoppers were the only insect pests observed in the field. However, they were not of sufficient levels to cause concern. We had significant rains in Central Florida during that time. Based on rainfall data collected from the two closest weather stations through the Florida Automated Weather Network (FAWN) Okahumpka received 24.72 inches and Ocklawaha received 36.88 inches of rainfall. This severely affected the crop at Bountiful Farms with the field reportedly remaining under water for 1-2 days at a time.

In Year 2, during the May-August growing period, no insect pests of significance were observed in the field. There were regular afternoon showers, so minimal supplemental irrigation was needed once the plants were established. Based on rainfall data collected from the two closest weather stations through the Florida Automated Weather Network (FAWN) closest to Bountiful Farms, Okahumpka Station received a total of 14.19 inches and Ocklawaha Station received 18.41 inches of rainfall. Since the elevation of the research plot was relatively the same as Year 1, this severely affected the crop with the field reportedly remaining under water for up to 24 hours depending on the amount of rain in a single event.

Similar to Year 1, a number of plants began to have a green wilt with a white cottony mycelium at the base. Samples that were rogued were wet at the base with mushy roots. Whole plant samples including roots were taken to the UF Plant Disease Clinic where they were diagnosed with Fusarium wilt (Fusarium oxysporum) and Pythium root rot (Pythium sp.). The disease pathogens collected in Year 1 were Fusarium oxysporum, Phytophthora, and Sclerotium rolfsii.

At the mid-July data collection for plant height measurements, a total crop loss of 27% was calculated. The highest occurrence of diseased plants were in ‘Local’ and ‘Black’ varieties. One hundred percent (100%) of the ‘Local’ plants in Block 2 and 86% (6 of 7 plants) in Block 3 had succumbed to disease. At 12 weeks after planting there was a 65% crop loss with only 39 plants remaining. Quantities of plants remaining for each variety were: ‘Black’ 10.7%; ‘Local’ 17.9%; ‘Day Neutral’ 53.6%; and ‘Festival’ 57.1%. The team decided to bring the trial at this location to an end because a significant number of data-collection plants were lost.

Although we lost the crop at Bountiful Farms in both years, we were able to conclude that sorrel is a crop that cannot tolerate wet conditions. These conditions resulted in plants that looked unhealthy and a combination of disease problems that could possibly render the crop a loss, especially in an organic enterprise where products for disease control may be limited. Farmers in Florida interested in planting sorrel should locate their field in the higher area of their property that has good drainage.

Dirty Dog Organics (DDO): In Year 1 at DDO we lost 2 ‘Black’ and 1 ‘Festival’ plants from the selected plants for data collection. Squirrels were the main pest of concern on this farm once the calyces were developed. They would collect the bolls and chew them in the large oak tree near the field so you could see the remnants below the canopy each day.

Whispering Oaks Farm (WOF): In Year 2 at Whispering Oaks, we had to move seedlings from Bountiful Farms to another location while we waited to get the land prepared. WOF was planted three weeks after Bountiful Farms. As the plants at WOF developed, we realized the phenotypical characteristics of the ‘Black’ variety were different from what we were familiar with, so we decided to terminate the trial for 2022 at WOF. A no cost extension was granted to allow us to time to repeat the trial on WOF for the 2023 growing season utilizing the same parameters as in 2022. Year 3 at WOF, an outbreak of fusarium and Coniella javanica in the required that data be analyzed on a mean-value-per-plant basis as opposed to the mean or total value per variety analysis used on DDO data from 2021.

Results

Data is taken from Dirty Dog Organics in 2021 and Whispering Oaks Farm in 2023. 

Plant Growth

Plant height measurements were taken of sample plants in two-week intervals beginning on July 21, 2021, 30 days after planting (above). The data was analyzed using ANOVA. Varieties grew at statistically even rates showing no discernible difference in vegetative vigor. However, in 2023 at Whispering Oaks Farm (below), sorrel plant height differed significantly among the varieties evaluated. Festival was significantly (P<0.05) the tallest sorrel variety with a mean height of 29.46 ± 1.08 inches. Day Neutral and Local did not show a statistically significant height difference (24.32 ± 1.08 and 23.28 ± 1.09 inches, respectively). By contrast, the ‘Black’ sorrel variety, with the shortest with a mean height of 19.84 ± 1.08 inches, was significantly lower than all other varieties.

Calyx Yield

SAS GLIMMIX's linear modeling tool was used to evaluate the data. An outbreak of fusarium and Coniella javanica in the 2023 trial required that data be analyzed on a mean-value-per-plant basis as opposed to the mean or total value per variety analysis in 2021.

Yield data was collected for calyces by weight with and without the seed boll. In Year 1 at Dirty Dog Organics, 'Local' produced a total 56.99 pounds and 30.74 pounds with and without bolls, respectively. 'Day Neutral' produced a total 46.17 pounds and 23.81 pounds with and without bolls, respectively. With bolls, the sorrel varieties ‘Local' and 'Day Neutral' had comparable mean yield responses.  The no-boll calyces assessment revealed that ‘Local’ had a significantly higher mean yield than ‘Day Neutral.’ The largest yields were achieved 9/26/21 – 10/9/21 (97 – 110 DAP), with yields then gradually declining for both varieties. ‘Festival’ produced no marketable calyces until November and ‘Black’ produced none. ‘Local’ showed a significantly larger mean weight w/o boll than ‘Day Neutral,’ conferring more yield per calyx picked. 

Due to disease eliminating several trial plants in 2023, data was derived from two harvests conducted on 10/11/23 and 10/27/23 . Only ‘Day Neutral’ and ‘Local’ produced calyces during this time. ‘Festival’ and ‘Black’ began to produce calyces between 11/21/23 and 12/6/23 but were unmarketable due to Coniella infection. The yield of ‘Day Neutral’ and ‘Local’ varieties did not differ significantly (P<0.05) with or without bolls. The mean weights of 'Day Neutral' and 'Local' with bolls were 1.60 ± 0.40 lbs. and 1.43 ± 0.40 lbs., respectively. Similarly, 'Day Neutral' and 'Local', with mean weights of 0.93 ± 0.22 lbs. and 0.81 ± 0.22 lbs., respectively, showed no difference in mean weight without bolls. 

The ‘Local’ and ‘Day Neutral’ varieties are suitable for production in Central Florida with multiple harvests received before the crop senesces. Since the ‘Day Neutral’ variety is technically supposed to be able to give a crop year-round, Central Florida farmers could start the seedlings early in the greenhouse and plant after the danger of frost has passed in mid to late March, then plant a second crop of ‘Day Neutral’ and/or ‘Local’ in June or July to extend the cropping season. The significantly higher mean yield (weight) of the ‘Day Neutral’ without bolls makes this an ideal variety to sell in this form to as it would take fewer calyces to make a pound compared to the ‘Local’. ‘Festival’ produced no marketable calyces until November and ‘Black’ produced none.

Because the sorrel leaves are edible, Dirty Dog Organics capitalized on the opportunity to harvest leaves from the crops to sell as greens to provide an added source of income. Due to sorrel’s rapid growth rate, judicial leaf harvesting does not significantly affect further plant development.

The sorrel plants get top heavy as they start to produce and fall over which makes it difficult to maneuver between the rows during harvest. Thus, we recommend that the spacing between rows be increased. The crop could also be planted in a single row as a perimeter crop.

Objective 2: To determine cost of production and economic viability.

Assuming the grower has preexisting access to land and land preparation inputs such as a tractor and rototiller, for the 3,978 square feet (38’ x 102’) trial site, pre-production input costs (ground cover, irrigation, harvest tools) totaled $625. Labor costs were calculated using a rate of $15.69 per hour, the average Florida farm worker pay in 2023 per the USDA NASS survey (https://quickstats.nass.usda.gov/). Planting required 4 hours at a cost of $62.76. Pre-harvest tasks required 42.5 hours at a cost of $668.83. Harvest season tasks required 32 hours $502.08. Total labor costs were $1,231.67 for 78.5 hours of labor over the season. Therefore, total reported production costs were $1,856.75.

Prices for fresh sorrel calyces with seed boll intact range from a low of $5 per pound to a high of $9.98 per pound, with an average price of $8.99 per pound. The best performing varieties in 2021 – ‘Local’ and ‘Day Neutral’, had statistically equivalent yields, with ‘Local’ yielding nearly 57 pounds of fresh calyces. This would yield an estimated revenue of $512.43 and an overall loss of $1,244.32. However, the 57 pounds only represent a combined 12 data plants in a 112-plant trial. Mean yield per ‘Local’ plant was 4.75 pounds in 2021, so a yield of 532 pounds over the trial site ($4,783 in revenue) is a possibility, leading to an potential $2,926.43 in profit. However, the study did not investigate whether the market would be able to handle this volume of sorrel within a single harvest season.

Sorrel leaves may sell for $3.49 per bunch. Yield and income from the greens were not part of this study.