Georgia and South Carolina share a border, a passion for football and pride in their peaches.

With the University of Georgia and Clemson University campuses separated by a mere 70 miles, the Bulldogs and Tigers began fighting it out on the football field in 1897. Over dozens of games, UGA and Clemson have had many dramatic moments that have changed the championship hopes of both teams.

The Bulldogs and Tigers are set to meet for the 65th time on Saturday, Sept. 4.

As pitched as the battle is on the football field, there’s an even deeper rivalry between the two states when it comes to their peaches.

Georgia earned its designation as the Peach State in the late 19th century when the state began exporting peaches to northern states, and the Georgia Legislature made it official in 1995.

Yet South Carolina produces more peaches than any other state in the country other than California.

Despite their football rivalry, UGA and Clemson researchers have worked together for many years to help peach producers overcome the challenges of growing the iconic and delicious fruit.

Tackling pests and downing diseases

Similar growing conditions in the two states create an agricultural playing field where Clemson and UGA peach researchers plan and coordinate defense strategies against diseases, pests and climate variations. Common insect pests include San Jose scale, plum curculio and peach tree borers. To help combat these culprits, the two universities created a joint appointment for a peach entomologist.

In 2016, Brett Blaauw joined the faculty as an assistant professor at both Clemson and UGA and as a member of both universities’ peach teams. His research focuses on integrating insect behavior and ecology to effectively and sustainably manage insect pests in Southeastern peach orchards.

“A lot of issues peach producers have in terms of insects span both states — and often the work we do in one state affects growers in both states,” Blaauw said. “In a lot of ways, it just makes sense to have someone in this split position.”

Blaauw works closely with pathologists and horticulturists from both colleges, as well as Clemson and UGA Cooperative Extension agents and peach producers in both states. This season, Blaauw is collaborating with Clemson plant pathologist Guido Schnabel and horticulturist Juan Carlos Melgar to investigate how various mulching techniques can impact soil health and the subsequent impacts on tree health and insect pests. Blaauw and Schnabel also research how using horticultural oil to manage San Jose scale can be incorporated into the current disease management program for peaches.

While Georgia lays claim to the Peach State moniker, South Carolina produces more peaches, likely due in part to how difficult it is to maintain the crop on the same land over many seasons, Blaauw said.

“Many issues in peach production come from growing on the same soil over and over,” he said. “In a state where there is a long history of growing peaches, it is becoming harder and harder to grow peaches because of insect and disease issues attacking the fruit.”

Soils in which producers have been growing peaches for years can harbor bacteria, fungi and nematodes that can stress the trees. Blaauw and other researchers are looking for ways to mitigate this by adding different mulches to create healthier soils with the goal of “making healthier trees.” One objective of the study is to study whether improving soil health can support “good” microbes, nematodes and bacteria that can attack the larvae of insect pests, such as peach tree borers and plum curculio, whose larvae attack tree roots. Other objectives focus on assessing the influence of improving soil organic matter on soil water and nutrient availability, and on fruit and tree diseases.

This research benefits peach growers throughout the Southeast, as many peach producers grow many of the same varieties, depending on climate and location, Blaauw added.

Huddling for a winning harvest

UGA Extension fruit disease specialist Phil Brannen and Schnabel communicate frequently, developing research projects based on problems they are seeing.

“We were losing a lot of peach fruit to fungal disease and, working with Guido, we were able to determine that brown rot in Georgia has significant resistance to a certain class of fungicides,” Brannen said. “We were then able to develop spray programs that have been very effective in controlling brown rot. Brown rot has gone from a serious problem across Georgia production to not much of a problem at all.”

When brown rot resistance reached South Carolina orchards, there was already a plan in place to combat it.

“This disease drives peach tree spray programs in South Carolina and Georgia,” Schnabel said. “Orchard floor management also helps minimize spring spore release. Clean orchard floors are key in controlling brown rot.”

Researchers from the two universities are also collaborating in an effort to combat Xap, the bacterium that causes the bacterial spot disease. This study, funded by the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) and led by Clemson plant bacteriologist Hehe Wang, includes Schnabel and Jose Payero from Clemson and UGA’s Brannen, as well as researchers from other institutions. Together, they are working to determine how to effectively manage this disease and build a disease forecasting system for future growers.

“Annual losses of more than $20 million are estimated during years when the disease is heavy in South Carolina and Georgia,” Wang said. “This disease is difficult to control and once it makes its way to an orchard, it’s there for the life of that orchard. It’s a constant battle.”

Other peach collaborations between the universities, include UGA peach horticulturist Dario Chavez, who is working with Clemson researchers on the use of plant growth regulators and rootstock trials to improve economic and environmental sustainability.

Chavez and Brannen are also collaborating with Clemson peach breeder and geneticist Ksenija Gasic in another NIFA-funded battle against Armillaria root rot, a soilborne disease that can remain dormant in the soil for many years, making infested land unsuitable for susceptible host plants for many years.

Although they have borne witness to good-natured ribbing by growers on both sides of the state line — with both Georgia and South Carolina claiming fruit superiority — both Blaauw and Brannen agree on one fact.

“Here’s the easy part. Both Georgia peaches and South Carolina peaches are 10 times better — maybe 100 times better — than California peaches, and that’s not even a lie,” Brannen said.

“Honestly, both are very good, but they are all better than California peaches,” Blaauw agrees, laughing.

When it comes to football, Brannen said he roots for UGA and Blaauw, a Midwest native, cheers for Michigan State. But their work in peaches will sustain the friendly rivalry between peach growers in Georgia and South Carolina for many growing seasons to come.

To learn more about UGA Peach Team research, visit peaches.caes.uga.edu.