Georgia growers harvested 45 million pounds of blueberries from over 20,000 acres in 2021, ranking 4th nationwide
(National Agricultural Statistics Service, 2023). The main production areas are concentrated in the southeastern part of the
state. South Georgia’s climate is characterized by mild winters, but spring freezes are common between March and
April. These late freezes represent the main challenge for blueberry production in the state. Other weather-related
events, such as warmer temperatures, high humidity, and precipitation during the harvest season, also can impact
fruit quality. Additionally, warm weather conditions increase the risk of biotic stresses, such as phytophthora root
rot and anthracnose fruit rot, which can compromise blueberry yields and fruit quality.
A brief survey was conducted during the annual blueberry update event hosted by the Bacon County UGA Extension office
in January 2023. The objective of the survey was to document blueberry producers’ choice of varieties and disease
concerns—this information would then be used to inform breeding priorities to develop new varieties adapted to the
Southeast growing environment. Twenty-six Georgia blueberry growers from eight southeastern counties reported 3,238
total acres of blueberry plantings. Bacon and Pierce were the top two counties, accounting for 47% and 24% of the
total reported acreage, respectively (Figure 1).
Figure 1. Reported Blueberry Acreage of Growers From Eight Georgia Counties.
Results indicated that 26 blueberry varieties were planted in the reported acreage across the eight producing
counties. Varieties that were planted on more than 5% of the total reported acreage are shown in Figure 2.
‘Farthing’ was the dominant variety (28% of reported acreage), followed by ‘Brightwell’ (22%). All other varieties
were planted on less than 10% of the reported acreage.
Among these varieties, Southern highbush (‘Farthing’, ‘Legacy’, ‘Meadowlark’, ‘Suziblue’, ‘Star’, and ‘Optimus’) and
rabbiteye (‘Brightwell’, ‘Premier’, and ‘Alapaha’) blueberries accounted for 61% and 39% of acreage, respectively.
Figure 2. Percentage of Acreage of Each Variety Reported. Varieties
occupying more than 5% of total acreage were plotted in this chart.
Rabbiteye varieties typically exhibit higher vigor and contribute to longer orchard life because of their stronger
root systems and enhanced tolerance to phytophthora root rot compared to southern highbush blueberries (Smith, 2012;
Markus et al., 2018).
In addition, the flower and fruiting time of rabbiteye blueberries usually occurs later than southern highbush, which
reduces the risk of early freeze damage and extends the Georgia fruiting season to mid-June. Because of this, frost
protection is less common in commercial rabbiteye production. However, growers recently reported postharvest
fruit-rot issues associated with rabbiteye blueberries (Oliver et al., 2021), and there is a need for new rabbiteye
varieties with enhanced fruit quality, size, flavor, and yield to increase the profitability of late-season
blueberry production.
Since 1940, the University of Georgia blueberry breeding program, in collaboration with the USDA, has made great
progress in developing rabbiteye varieties, including ‘Brightwell’ and ‘Alapaha’. These varieties have increased
fruit size, reduced seed size, closely synchronized ripening time, and long shelf life. However, the genetic base
of rabbiteye breeding is narrow, tracing back to only four wild races (Lyrene, 1987). Rabbiteye blueberry
(Vaccinium virgatum Ashei) is an outcrossing, hexaploid (2n = 6x = 72; in other words, there are
two sets of chromosomes, one from each parent; and six sets of these chromosomes are present in each cell, for a
total of 72 chromosomes per cell) species endemic to Georgia, Florida, and Alabama (Lyrene, 2005). To continue
improving the quality of rabbiteye blueberries, our breeding program is working to broaden the genetic base of
rabbiteye germplasm.
Southern highbush blueberries (Vaccinium spp.; 2n = 4x = 48) were created through interspecific
hybridization of northern highbush (V. corymbosum L.; 2n = 4x = 48) and low-chilling diploid species
(2n = 2x = 24), mainly V. darrowii (Draper & Hancock, 2003). The UGA breeding program started breeding
southern highbush plants in the 1980s, and ‘Suziblue’ was a UGA variety released in 2010 (NeSmith, 2010). Georgia
commercial acreage for southern highbush blueberries has increased significantly in the past decade because of many
favorable traits, such as early ripening, large fruit size, high yield, and self-fertility. However, planting
southern highbush requires high organic matter (Clark & Moore, 1991) and frost protection, which can significantly
increase the cost of orchard establishment and operation. Early-season frosts are frequent in South Georgia and can
cause significant or total yield loss of unprotected southern highbush orchards. Developing southern highbush
varieties with delayed blooming time will reduce the risk of early frost damage.
In addition to reporting the varieties in production, surveyed growers provided rankings of eight blueberry diseases
or pests based on their perception of disease impact (Figure 3). Phytophthora root rot was reported to have the
highest impact, followed by anthracnose fruit rot, leaf rust, yeast rot, early stand loss, thrips, bud mites, and
mummy berries. Phytophthora root rot disease (caused by Phytophthora cinnamomi Rands) in blueberries is
prevalent in heavy soils (higher clay) with poor drainage. Infected plants suffer from root necrosis, leaf
chlorosis, stunted growth, defoliation, and eventually death (Erb et al., 1987). ‘Legacy’ was reported to have
disease resistance to phytophthora root rot (Yeo et al., 2016). Anthracnose fruit rot (caused by fungal pathogen
Colletotrichum fioriniae) is a widespread disease across major blueberry production regions of North
America. Disease resistance to anthracnose fruit rot was identified in several highbush
varieties such as ‘Elliott’, ‘Brigitta’, and ‘Legacy’ (Miles & Hancock, 2022). Reports of genetic markers
associated with anthracnose resistance (Jacobs et al., 2023) can be used to accelerate the development of resistant
varieties adapted to the Southeastern growing environment.
Figure 3. Grower's Ratings on Disease/Pest Impact on Farm Production. The
rating scale is 1 to 10, with 1 being the least impact and 10 being the highest impact.
In conclusion, UGA’s blueberry breeding program is collaborating with blueberry pathologists and entomologists to
screen for disease resistance against these blueberry pathogens and pests among our breeding lines. Breeding efforts
aim to not only improve fruit size, quality, and yield, but also resistance to early-season frost, disease, and
pests for both southern highbush and rabbiteye varieties.
References
Clark, J. R., & Moore, J. N. (1991). Southern highbush blueberry response to
mulch. HortTechnology, 1(1), 52–54. https://doi.org/10.21273/HORTTECH.1.1.52
Draper, A., & Hancock, J. (2003). Florida 4B: Native blueberry with exceptional breeding
value. Journal of the American Pomological Society, 57(4), 138.
Erb, W. A., Moore, J. N., & Sterne, R. E. (1987). Response of blueberry cultivars to
inoculation with Phytophthora cinnamomi Rands zoospores. HortScience, 22(2), 298–300. https://doi.org/10.21273/HORTSCI.22.2.298
Jacobs, M., Thompson, S., Platts, A. E., Body, M. J., Kelsey, A., Saad, A., Abeli, P., Teresi, S.
J., Schilmiller, A., Beaudry, R., Feldmann, M. J., Knapp, S. J., Song, G., Miles, T., & Edger, P. P. (2023).
Uncovering genetic and metabolite markers associated with resistance against anthracnose fruit rot in northern
highbush blueberry. Horticulture Research, 10(10), uhad169. https://doi.org/10.1093/hr/uhad169
Lyrene, P. M. (1987). Breeding rabbiteye blueberries. Plant Breeding Reviews, 5, 307–357.
https://doi.org/10.1002/9781118061022.ch8
Lyrene, P. M. (2005). Breeding low-chill blueberries and peaches for subtropical areas.
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Makus, D. J., Spiers, J. M., Patten, K. D., & Neuendorff, E. W. (2018). Growth responses of
southern highbush and rabbiteye blueberry cultivars at three southern locations. In Blueberries (pp.
73–82). Routledge. https://doi.org/10.1201/9781315138497-8
Miles, T. D., & Hancock, J. F. (2022). Inheritance of resistance to anthracnose fruit rot
caused by Colletotrichum fioriniae in highbush blueberry. International Journal of Fruit
Science, 22(1), 160–169. https://doi.org/10.1080/15538362.2021.2022567
NeSmith, D. S. (2010). ‘Suziblue’southern highbush blueberry. HortScience, 45(1), 142–143.
https://doi.org/10.21273/HORTSCI.45.1.142
Oliver, J. E., Ali, E. (2021). Identifying post-harvest rots of Georgia blueberries and
assessing pre-harvest fungicide applications for prevention of post-harvest diseases [White paper]. Small
Fruits Consortium. https://smallfruits.org/files/2021/12/2021-R-13-Progress-Report.pdf
Smith, B. J. (2012). Survival of Southern Highbush blueberry cultivars in Phytophthora root
rot-infested fields in south Mississippi. International Journal of Fruit Science, 12(1–3), 146–155. https://doi.org/10.1080/15538362.2011.619361
Yeo, J. R., Weiland, J. E., Sullivan, D. M., & Bryla, D. R. (2016). Susceptibility of
highbush blueberry cultivars to phytophthora root rot. HortScience, 51(1), 74–78. https://doi.org/10.21273/HORTSCI.51.1.74
Status and Revision History
In Review on Dec 19, 2024
Published on Mar 07, 2025
