North Carolina blueberry farmers have some solid options when it comes to what cultivated varieties – or cultivars – of blueberries they grow, but various demands on those farmers mean they’re always in need of improved blueberries that meet their evolving needs. That’s where blueberry breeding research comes into play, along with the research stations operated through partnership between the N.C. Department of Agriculture and Consumer Services and NC State University.
Blueberry varieties such as Legacy, Star, O’Neal, Suziblue and New Hanover have become standards in North Carolina. Each variety falls into early, mid or late season, which means North Carolina blueberry farmers who grow multiple varieties can stretch their season each year and give customers what they’re looking for on grocery store shelves, farmers markets and pick-your-own farms. They have consistently performed well under North Carolina conditions. However, the varieties that were once considered cutting edge eventually begin to show their age.
“Each of our growers [in North Carolina] rely heavily on two or three main cultivars, and they’re always trying new ones to kind of fill in gaps with ones that will hopefully work better for them – [for example] to have a higher yield or produce earlier in the season – but a lot of the ones they have now are 20 to 40-year-old cultivars,” research scholar Jessica Spencer explained. “They’ve been out for a really long time, and so they definitely need something that is more suited to our markets these days.”
Consumers these days are looking for bigger, firmer berries, and fewer workers means farmers need to rely more on berries that can be effectively machine-picked. New diseases have emerged too, and late winter is getting warmer. That’s why researchers with North Carolina State University’s Department of Horticultural Sciences have been working on the next generation of blueberries.
Spencer is one of those researchers, along with associate professor Hudson Ashrafi, who leads North Carolina’s public blueberry breeding program – a program that involves lots of work at the Castle Hayne Horticultural Crops Research Station. Their goal is simple in concept but complex in execution: develop blueberry varieties specifically adapted for North Carolina growers. That means breeding plants that can thrive in the state’s climate while producing the larger, firmer, more flavorful berries today’s consumers expect. It also means helping growers adapt to modern production practices such as machine harvesting.
“So traits favorable for that are needed – firm berries, loose fruit clusters, upright plants, green berries that stay on the bush and ripe berries that come off easily,” Spencer explained.
Those improvements don’t happen overnight. The time from making the initial cross between two parent plants until the time of patenting and releasing a new variety can take 15 years or more. During that time, researchers evaluate thousands of seedlings before narrowing them to a handful of promising selections that are tested for years under North Carolina growing conditions.
Yield also remains a top priority. To develop varieties with good yield and the favorable quality aspects (size, flavor, etc.), researchers are also selecting for traits that help plants withstand North Carolina’s unique environment. Blueberries require a certain amount of winter chilling before they bloom. Varieties developed farther south may bloom too early and become vulnerable to late winter freezes, while varieties bred for colder climates may never receive enough chilling to perform well in North Carolina.
“Our climate is changing and on top of that there’s always going to be new disease pressure and new needs that growers have. So, it’s really important to keep a program like this up and running and bringing in new genetics and making sure we have the ability to breed a better blueberry for North Carolina,” Spencer said. “It’s a pretty strong industry in the state right now.”
That focus on North Carolina distinguishes the state’s public breeding program from many private breeding companies. While private companies often develop varieties for broad commercial markets, the NC State program evaluates selections specifically for North Carolina’s climate, disease pressures and production practices.
“Companies may trial varieties here, but they aren’t specifically breeding for North Carolina,” Spencer said.
Public breeding also helps reduce costs for growers. Ashrafi said many privately developed varieties require growers to pay big licensing or royalty fees, but North Carolina’s public breeding program instead develops varieties intended to provide growers with affordable cultivars with lower royalties that aren’t based on fee structures like some of the larger private companies are moving toward. The locally adapted options support one of the state’s most valuable specialty crops. North Carolina consistently ranks among the nation’s leading blueberry-producing states, placing sixth or seventh nationally depending on the year.
The breeding program is also becoming more efficient through research supported by grants. Funding from the N.C. Department of Agriculture and Consumer Services’ Specialty Crop Block Grant Program allowed Spencer to partner with NC State engineering professor Edgar Lobaton to develop machine-learning technology that analyzes photographs of harvested blueberries. The system can already measure berry diameter, circumference, color, uniformity and ripeness from a simple photograph. Researchers are expanding the technology to automatically identify additional characteristics such as stem scars, calyx size, fruit splitting, diseases and other quality traits.
Another project, funded by the N.C. Blueberry Council, has demonstrated that growing seedlings in pots instead of planting them directly in the field can reduce losses while allowing researchers to evaluate potential varieties one to two years sooner. Together, those grant-funded projects and others help address one of the biggest challenges in plant breeding, which is time.
“It allows me to hire temporary workers – usually college students – so we can get out in the field. It’s a numbers game. The more numbers I can look at, the more things I can plant in the field, the more selections we can make, the more things I can test with growers, then the more likely we are to find something North Carolina growers can use,” Spencer said.
That investment is beginning to pay dividends again. After a lull in staffing, the breeding program has begun introducing new varieties, such as Rowan, formerly known as NC3104. It’s a sibling to the established New Hanover variety, so they have similar traits, but Rowan is a slightly earlier variety that doesn’t have stem tear issues like New Hanover. The researchers are now preparing to release two additional selections that have improved attributes, currently called NC5288 and NC5289. Ashrafi hopes those introductions signal a return to more regular releases.
“We had some downtime, and now we are back up and have so many advanced selections that can be introduced, and I think we should be naming them and releasing them as fast as possible,” Ashrafi said. “We have something to overlap every year or every couple of years now.”
These three documents are official releases of Rowan, NC5288 and NC5289
There are now about 80 to 90 advanced selections in the breeding program, and that steady pipeline matters because establishing a blueberry field requires significant time and investment. Growers expect a planting to remain productive for decades, which makes the choice of which variety to plant one of the most important decisions they make.
For North Carolina growers, the state’s public breeding program helps ensure those choices continue to improve – one new cultivar at a time.