Jay Spiers and Libby Neal, Auburn University

As blackberry is the state fruit of Alabama, we feel there is great potential to expand blackberry production, increase consumer acceptance, and increase profitability for growers in Alabama. There are 224 acres of blackberry production in Alabama based on the 2022 Census of Agriculture, up from 143 acres reported in 2017. These producers market their fruit primarily as U-Pick operations, or at roadside stands and farmer’s markets. The standard cultivar (variety) produced in Alabama appears to be ‘Kiowa’. ‘Kiowa’ is a resilient and highly productive “thorny” cultivar with large berries and relatively low sugar content compared to most available blackberry cultivars. There are many new thornless blackberry cultivars that warrant evaluation in Alabama. There is also interest in heat-tolerant raspberries and primocane-fruiting blackberries that could allow for new market windows.

There are several concerns with growing raspberries and fall-producing blackberries in the hot, humid South. Raspberry production in the South is not recommended due to the heat but may have potential under shade. Similarly, high temperatures may negatively affect flower production of primocane-fruiting blackberries resulting in low yields. Fruit exposed to high temperatures may be of inferior quality, or abort under extreme conditions. There may be unforeseen issues with insect pests or pathogens growing fruit during late summer months. However, there is preliminary evidence that fall-fruiting blackberries have some potential in the South. We have trialed some of the primocane-fruiting blackberries focusing on floricane production (spring/summer crop) previously in central Alabama and have observed flower and fruit production on primocanes – even though the primocane crop was neglected to focus on the floricane crop.

This study was implemented to determine cultivar recommendations for blackberry and raspberry production in central Alabama, and to determine whether incorporating shade enhances productivity and fruit quality enough to justify the extra expense. We established 19 blackberry cultivars and 11 raspberry cultivars with 8 single-plant replications under shade (Fig. 1) and separately in full sun (Fig. 2) in April 2023. The plants were primarily liners from tissue culture facilities, and we began collecting our first yield data in May 2024. Data collection for each harvest date consists of yield, weight of 25 berries, and number of fruit with white drupelets/25 fruit sample. Soluble solids content (SSC) and titratable acidity (TA) will be determined for at least 3 sample dates (3 consecutive weeks). The blackberry cultivars used in this study are: ‘Big Daddy’, ‘Caddo’, ‘Columbia Star’, ‘Eclipse’, ‘Galaxy’, ‘Kiowa’, ‘Natchez’, ‘Navaho’, ‘Osage’, ‘Ouachita’, ‘Ponca’, ‘PrimeArk 45’, ‘PrimeArk Freedom’, ‘PrimeArk Horizon’, ‘PrimeArk Traveler’, ‘Snowbank’, ‘Sweetie Pie’, ‘Twilight’, and ‘Von’. The raspberry cultivars are: ‘Caroline’, ‘Dormanred’, ‘Glencoe’, ‘Heritage’, ‘Himbo Top’, ‘Jewel’, ‘Joan J’, ‘Mac Black’, ‘Nantahala’, ‘Polka’, and ‘Royalty Purple’.

Figure 1. Caneberry under shade being harvested at the Chilton Research and Extension Center in Clanton, AL 2024
Figure 1. Caneberry under shade being harvested at the Chilton Research and Extension Center in Clanton, AL 2024
Figure 2. Evaluation of caneberries cultivated in full sun at the Chilton Research and Extension Center in Clanton, AL 2024
Figure 2. Evaluation of caneberries cultivated in full sun at the Chilton Research and Extension Center in Clanton, AL 2024

We can only report some initial observations at this point. ‘PrimeArk Freedom’ is the earliest fruiting cultivar in this study, by approximately 2 weeks this year. ‘Snowbank’, a white blackberry developed by Luther Burbank in the 1890’s, is quite unique and likely best used as a novelty plant or for ornamental purposes. It is small in stature, quite thorny, and loaded with flowers in the spring followed by many small white fruit (Fig. 3). We will not be collecting yield data for ‘Snowbank’. ‘Von’ appears to be the least vigorous plant and may not be suited for this region (Fig. 4). ‘Big Daddy’, licensed as a home garden variety, was noteworthy in this first year for its large fruit and distinctive long-shaped berries (Fig. 5). Many of the blackberry cultivars developed by the University of Arkansas breeding program appear promising for both full sun and shade production. It is too early to make comparisons, but we are pleased with the sweetness of ‘Ponca’ and ‘Caddo’.  

Figure 3. ‘Snowbank’ white blackberry
Figure 3. ‘Snowbank’ white blackberry
Figure 4. ‘Von’ blackberry
Figure 4. ‘Von’ blackberry

As expected, the raspberry plants are not thriving compared to the blackberry plants. ‘Dormanred’ is the only raspberry known to thrive in the South and that holds true for this study (Fig. 6). However, we predict that ‘Dormanred’ will have the lowest soluble solids (sweetness). Thus far it appears that the low yields for our raspberry cultivars, and perceived short postharvest life, do not warrant commercial production in central Alabama for fresh fruit utilizing the growing systems we have employed. However, we are getting fruit on all the raspberry cultivars, and likely will be able to recommend certain cultivars for home use.

Data is still being collected and processed to make a comparison and determine if the cost of shade cloth is justified for southern growers. 30% shade cloth used in the study is made of Aluminet, a reflective material. For both blackberries and raspberries, we have observed increased vigor and higher fruit quality in plants under shade. Ambient air temperature and soil temperature is collected on Watchdog Data Loggers, and we expect to see significantly lower recorded temperatures under shade.

Figure 5. ‘Big Daddy’ blackberry
Figure 5. ‘Big Daddy’ blackberry
Figure 6. ‘Dormanred’ raspberry
Figure 6. ‘Dormanred’ raspberry