Phytophthora Root Rot on Southern Highbush Blueberry in Florida

Roots serve the vital function of water and nutrient uptake for plants. Healthy roots provide the foundation for productive blueberry bushes and require the right horticultural inputs and soil environment to thrive. Less-than-ideal conditions can result in unhealthy, rotten roots, sometimes caused by disease. The most common and destructive root rot disease of southern highbush blueberry (SHB) in Florida is Phytophthora root rot (PRR), caused by the oomycete pathogen Phytophthora cinnamomi Rands. Oomycetes, or “water molds,” favor water-saturated environments. The distinction between oomycetes and fungi is important for disease management, because many fungicides work for only one group, not both. Worldwide, P. cinnamomi is a devastating pathogen of approximately 5,000 woody plant host species. For blueberry growers in Florida, PRR is a persistent problem that is currently managed through careful site selection, preparation, and routine Phytophthora-specific fungicide applications.