Peaches are the most important tree fruit industry in the southeastern United States. The majority of production is concentrated in South Carolina (5,868 bearing hecacres) and Georgia (4,856 hectares), and the value of the total utilized peach production int he both states combined was estimated to exceed $69 million in 2008. The humid, warm southeastern climate is conducive for fungal and bacterial disease development and epidemics.
In any given year, brown rot, caused by Monilinia fructicola, can cause substantial damage ($9.8 million est. 2003) on peach fruit. Although an integrated approach is currently being used to control brown rot, including sanitation practices and cultural methods, management still depends heavily on two or three fungicide applications prior to harvest. Over the past 25 years or so, these applications have relied primarily on fungicides within a single class – the demethylation inhibitors (DMIs), but more recently, spray programs have shifted to rotations of respiration inhibitors (RIs) with DMIs. There is now extensive resistance to the DMIs in many locations, and if resistance to RIs were to increase, there would be a catastrophic control failure with the current system. Producers must know that a resistance shift has occurred if they are to adjust their spray programs to other chemical classes (i.e. benzimidazoles) to manage the disease effectively.
This project has developed a fungicide resistance monitoring program that has recently been implemented in the peach growing region of Georgia. For more information on this project, please visit the UGA Extension Peach website.