Historically, blueberries are an important crop in Alabama. Blueberry acreage has experienced a 38 percent increase over the past 15 years, evidence of a growing interest in cultivating this delicious and highly nutritious fruit crop.

In the past decade, new rabbiteye blueberry cultivars with improved fruit quality attributes have been released. These could aid in sustaining and expanding the growth of the industry. However, the performance of these cultivar needs to be tested in Alabama conditions before recommendations are made to the growers. To accomplish this, a research plot was established at the Chilton Research and Extension Center in Clanton, Alabama in 2019.

Since then, this research plot has been used to evaluate the vegetative growth, productivity, and fruit quality attributes of the following rabbiteye blueberry cultivars: ‘Alapaha’, ‘Krewer’, ‘Ochlockonee’, ‘Pink Lemonade’, ‘Titan’, and ‘Vernon’. These cultivars have been compared with the following standard cultivars: ‘Climax’, ‘Powderblue’, ‘Premier’, and ‘Tifblue’. During the first two seasons after planting, the crop was removed from the blueberry bushes in order to promote better root system establishment and plant longevity.

2022 and 2023 Cold Injury

A late-spring freeze event occurred March 12-13, 2022, where temperatures fell to 24 degrees F. Row covers were used to protect the experimental bushes, which increased the temperature under the cover by as much as 8 degrees F. This successfully protected the plants until mid-March, when strong winds of more than 35 miles per hour blew away the row covers and exposed the plants to freezing temperatures. At that time, the cultivars had between 20 and 100 percent open flowers due to the warming trend in the beginning of March. All cultivars sustained cold injury, and the most advanced blueberries had a complete crop loss. Similarly, the late-spring freeze event on March 19, 2023, when the temperature lowered to 20 degrees F, decimated the entire crop, as the plants were setting fruit at that time and were highly sensitive to freezing temperatures.

2024 Research

Figure 1. Ripening season of rabbiteye blueberry cultivars grown in 2024.

The milder winter and spring conditions in the 2024 season led to a typical cropping of established blueberry bushes in the trial, and the major results are discussed below.

Data was collected to determine the season of ripening of the studied cultivars (figure 1). ‘Pink Lemonade’ fruit was the earliest to mature in 2024 (figure 2). Its harvest started in mid-May, and was followed by ‘Alapaha’, ‘Krewer’, and ‘Vernon’, which started to mature a few days later. At the same time, harvest started for traditional early season cultivars, ‘Climax’ and ‘Premier’. ‘Titan’ fruit started to ripen at the end of May, as did the fruit for the well-established ‘Tifblue’ cultivar. Harvest of the ‘Ochlockonee’ and ‘Powderblue’ crops started late in the season, at the beginning of June.

Individual yield per plant was measured on each harvest date and the results for total yield per plant are shown in table 1. Cultivar productivity varied between 2.2 pounds per plant for ‘Pink Lemonade’ to 12.3 pounds per plant for ‘Ochlockonee’, representing a six-fold difference in the cropping potential between the two cultivars. The low yield of ‘Pink Lemonade’ is not a surprise, as this cultivar is recommended primarily for homeowners and landscape use. Newly released, early season cultivars ‘Alapaha’, ‘Krewer’, and ‘Vernon’ exceeded the yield of the current standard cultivars, ‘Climax’ and ‘Premier’, while ‘Titan’ produced the same yield as ‘Climax’ and ‘Premier’.

To determine fruit quality attributes, a ten-berry sample was collected from each individual experimental plant at each harvest event. Measurements for berry weight and total soluble solids were then averaged across all harvest dates to determine the seasonal mean values presented in table 1. The results suggest that ‘Titan’ produced the largest berry size, as the mean individual berry weight was 3.3 grams. This was followed by ‘Krewer’, with an average berry weight of 2.3 grams (figure 3). Although ‘Ochlockonee’ plants produced the highest yield per plant, their berries were also large, measuring 2 grams on average. The results for total soluble solids during 2024 varied between 12.6 degrees Brix for ‘Pink Lemonade’ and 15.9 degrees Brix for ‘Climax’ and ‘Titan’, evidence of the good fruit sweetness of last season.

Looking Forward

Studies will continue to completely assess cultivar performance in multiple seasons. New rabbiteye blueberry cultivar evaluation will help growers select the best suited cultivars for their growing location and targeted market, which can lead to improved sustainability and profitability for Alabama blueberry farms.