Brown rot fungus, also known as Monilinia fructicola, can be a peach’s worst nightmare.
Generally, the first sign of the disease is in springtime when dying blossoms turn to mush, and a gray, fuzzy spore mass is formed on the branch.
Georgia peaches have, luckily, been mainly spared of this disease due to extensive research and experimentation.
Phillip Brannen, University of Georgia Cooperative Extension fruit plant pathologist, says that research is being conducted on brown rot of peaches in relation to new chemicals in the marketplace. He says that the goal is to determine the efficacy of new chemicals compared to the standard materials.
Brown rot fungus readily develops resistance to chemicals. “We continually have a need for new classes of chemistry,” Brannen says. “So we need lots of different classes of chemistry to rotate in our program.”
Brannen says researchers try to look at chemicals that are a year or two away from being released to the public. They are compared to the standard chemicals and recorded on their efficiency.
According to Brannen, another avenue of research is looking at some of the older chemistries and new ways to use those chemistries. “One of the things that has been researched in the Northeast United States is looking at some later applications of Captan just before harvest,” he says. Captan is a general-use pesticide.
Brannen explains that older fungicides are being tested on number of applications and timing of applications. “Captan is an old, old standard chemical fungicide. But this is a new way to look at it,” he says. “We are always trying to fine-tune the system so we can get better management.”
With all of the research that has been conducted and all of the information gathered when looking at resistance in some of the fungicides, Georgia actually has pretty solid control of brown rot in peaches, says Brannen.
“We have fungicides that we apply in-season, and we also have one post-harvest fungicide that’s applied at the packing line,” Brannen says. “The combination of those has reduced brown rot significantly since 2000.”
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