Clemson peach experts help fruit growers fight fungus
March 23, 2009
CLEMSON, SC – March 23, 2009 – Imagine the well-known Carolina Peachoid covered in rust, then shrunken and gooey. The Gaffney orangey-yellow I-85 icon — a water tower resembling a giant peach — would look a lot like a real peach with brown rot. Clemson University peach specialists are helping Southeastern growers control the destructive fungus.
Brown rot (Monilinia fructicola) is a hardy survivalist, adapting to control efforts. The pathogen at specific locations has developed resistance to some fungicides, according to reports from South Carolina. The situation poses a big problem for South Carolina and Georgia, which behind California rank second and third in U.S. peach production. The two states account for 25 percent of the nation’s fresh peaches, selling about $60 million worth of peaches a year.
“The chemicals that are being used these days to control brown rot are site-specific chemicals,” said Clemson plant pathologist Guido Schnabel, the South Carolina state specialist for fruit diseases. “That means they attack the fungus at one particular place. So the fungus has a fairly easy way to produce resistance against those chemicals.”
Schnabel and colleagues A. Amiri, Phil Brannen and Harald Scherm (the latter two are from the University of Georgia) have come up with new a weapon to battle brown rot. It was tested in 2008 and is ready for use this growing season.
“We’ve developed a kit that will enable growers to determine the resistance profile in their respective areas,” said Schnabel. “What we do is we go to the grower’s’ site. We collect samples, and within three days, using that kit, we can determine what kind of resistance profile the grower has in their respective area. So right off the bat a grower starts out with the correct sprays and uses the correct chemicals knowing what resistance profile they have.”
Besides saving the growers money and helping the environment by using fewer chemicals, the work by Schnabel and colleagues has more far-reaching benefit.
“The research and techniques can be used for other stone-fruit crops because this is a disease that not only affects peaches, it also affects nectarines and cherries and plum,” said Schnabel.
The American South has long been linked to peaches, but they originated in China, where they have been cultivated for more than 4,000 years. The Spanish brought the peach to the New World in the 1500s, where Franciscan Monks propagated it along the South Carolina coast. It wasn’t until the 1850s that South Carolina began growing peaches commercially. In 1984, South Carolina growers harvested the record peach crop of 480,000 tons. Today, crop yield is about a fourth of the record harvest, owing to drought, disease, increased costs and decreased demands.
