Phytophthora plurivora root rot

Phytophthora plurivora is a soil-borne oomycete pathogen responsible for serious root and collar rot diseases in various woody plants and shrubs. Due to its wide host range and adaptability, it is considered a significant threat in nurseries, forest ecosystems, and ornamental plantations globally.

The pathogen specifically targets the vascular system of its host plants. Common victims include various oak species, beech, and fruit-bearing trees. By attacking the root cortex, the organism restricts water and nutrient uptake, leading to a general decline in plant health that is often misidentified as drought stress or nutrient deficiency.

Visual symptoms frequently manifest as yellowing (chlorosis) of foliage, stunted growth, and canopy thinning. A diagnostic hallmark is the presence of dark, moist, or sunken lesions on the root collar, often accompanied by a distinct reddish-brown discoloration of the inner bark tissues when examined closely.

Environmental conditions play a critical role in the epidemiology of Phytophthora plurivora. The pathogen thrives in waterlogged soils and temperate climates. It produces motile zoospores that require free water to swim through soil pores and infect healthy root tips, making poor drainage and frequent flooding primary drivers of disease spread.

Management and preventative strategies are essential to mitigate the economic impact of this pathogen:

• Strict sanitation protocols for nursery equipment and pots.
• Implementation of robust drainage systems to prevent water saturation.
• Avoidance of importing plants from regions known for high pathogen pressure.
• Application of phosphonate-based fungicides to inhibit pathogen metabolism.
• Regular inspection of the root zone for early signs of necrotic tissue development.