Brown rot is one of the most economically and ecologically important diseases affecting California’s $100 million prune industry, say plant pathologists with The American Phytopathological Society (APS).

According to Themis Michailides, plant pathologist with the Department of Plant Pathology, University of California, Davis, the impact brown rot has on California’s prune industry is of continued importance as the state produces approximately 99 percent of the United States prune supply and 60 percent of the world supply.

“Brown rot is a hard disease to detect, which makes it a very difficult disease for growers to manage and makes it the primary plant disease of concern to growers,” Michailides said. “It is a complex disease that can be caused by two fungal pathogens, and can cause multiple sets of symptoms that occur throughout the growing season,” he said. Brown rot can cause blossoms to collapse in spring, rot of green fruit in mid season, and decay of mature fruit in late season.

To combat this disease and keep prunes in ample supply worldwide, plant pathologists have applied research to develop a “decision support system” that helps growers to optimize fruit production using integrated pest management for each orchard. This system enables growers to identify the conditions that may trigger brown rot infections and determine the best time to apply disease management tools.

With continued research, this system may be applicable to other stone fruits susceptible to brown rot. “An improved decision system will save growers unnecessary costs, protect the environment from unnecessary sprays, and provide more efficient brown rot management in California stone fruit,” said Michailides.

More information on the complexity of brown rot of prunes and research to manage this disease is available on the APS website at www.apsnet.org/online/feature/prune/. APS is a non-profit, professional scientific organization. The research of the organization’s 5,000 worldwide members advances the understanding of the science of plant pathology and its application to plant health.