For the past two years, Auburn University’s College of Agriculture has conducted research to help peach farmers combat a crop-destroying disease: bacterial spot. Led by Dr. Edgar Vinson, assistant extension professor at the Chilton County Research & Extension Center in Clanton, Alabama, researchers aim to utilize a type of virus called a bacteriophage to counter bacterial spot.
According to Vinson, Xanthomonas arboricola pv. pruni, the bacterium that causes bacterial spot, attacks the leaves of peaches and creates dark, water-soaked lesions that kill the affected tissue. These lesions then spread and cause the leaves to fall off the trees. Without the nutrients from the leaves, the peaches never properly mature and struggle to reach marketable size, leaving growers with fewer yields and lower earnings. If the peaches become infected, they might still be marketable depending on when they get infected. However, bacterial spot infections early in the season can devastate crops and leave them unsalable.
Bacterial spot is difficult and costly to deal with. It spreads through wind and rain, infecting other parts of the infected trees, other trees and even other orchards. According to the Auburn University College of Agriculture, Alabama fruit farmers spend around $1.2 million per year to deal with bacterial spot. To protect their crops, farmers often spray their peach trees with copper-containing fungicides, but these fungicides can have major negative consequences for both growers and the environment.
Like the disease, these fungicides can cause defoliation, lesions in leaves, a reduction in yield or even no yield at all. According to Vinson, everything down to the water’s pH and calibration of the spray equipment can affect whether the fungicide causes damage to the plant.
“There are a lot of things that can go wrong with copper,” Vinson said.
To make matters worse, the bacterium has built up resistance to copper fungicides, making them less effective.
Despite these drawbacks, copper fungicides remain the standard in preventing bacterial spot due to their relative effectiveness. Two years ago, however, Vinson heard that a biotechnology company called OmniLytics had developed bactericides called AgriPhage, one of which targeted bacterial spot in peaches by using bacteriophages. Interested, Vinson decided to contact them and give it a shot.
Bacteriophage technology, also known as phage technology, is the main focus of Vinson and his research team. Phage technology uses viruses called bacteriophages to target bacteria. After being applied, these viruses connect to the surface of the bacteria, inject their own genetic material, take over the bacteria’s reproduction and split the bacteria open, killing it and unleashing more viruses that search for other bacteria to infect.
Vinson believes phage technology is a good option for combatting bacterial spot, citing that the virus is specific to peaches.
“There may be some other solutions out there, and I’d certainly be open to evaluating those as well,” Vinson noted. “But this one is interesting because of its specificity. The viruses are specific for that bacteria that causes bacterial spot in peaches.”
As this project continues, Vinson hopes it will serve as an introduction to agriculture by highlighting farmers’ challenges, environmental concerns, and the extensive work that goes into producing our food. In the end, Vinson hopes to encourage younger people who want to contribute to society to enter into agriculture.
“The project makes me think of how much more brain power is needed, and creative solutions are needed, to address some of these problems,” Vinson said. “Younger people are getting out into the world, and they may wonder what it is they can do, how can they contribute to society, and I think a real good way to do that is through agriculture.”
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