Common Diseases: Phytophthora root rot

Biology

Phytophthora root rot is caused by a fungal infection of the roots resulting in root death and overall plant decline. Infected plants may appear off-colored and stunted and may show symptoms of wilting prior to death. Plants growing in excessively wet soils (maybe for only several weeks) are most vulnerable to infection. These fungi thrive in poorly drained soils and can be spread by water movement as well as by movement of infested soil, infected plants and plant debris. Cinnamon-brown discoloration of infected roots and lower stem tissues are symptoms of this disease, but also can be symptoms of other root rot diseases. Laboratory isolation or ELISA tests confirm diagnosis.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Plant only in deep, well-drained soil.
• Correct drainage if water puddles near plants.
• Use resistant species or cultivars, such as Hall or Sargent crabapples and certain rhododendron species and varieties. Avoid planting susceptible plants into soil where root rot has been a problem.
• Do not move infected plants, plant debris, or infested soil to other areas.
• Destroy infected plant material including roots when feasible.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

None recommended.

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