Integrated Pest Management
Phytophthora
Phytophthora spp.
![phytophthora](/planthealth/ipm/images/ornamental-pest-guide/diseases/phytophthora_ontario-tender-fruit-ipm_omafra.gov.on.ca.jpg)
Discoloration and crown rot (Ontario Ministry of Agriculture, Food and Rural Affairs, Queen's Printer for Ontario)
Root rot caused by Phytophthora (William M. Brown Jr., Bugwood.org)
Hosts, Symptoms & Signs
- many deciduous trees and shrubs; some conifers
- tree or shrub starts wilting, then dies
- rotten roots
- lower stem areas can be discolored and rotten
- motile spores can swim in a film of water to spread
Disease Cycle
- soilborne pathogen; it can live in decaying matter until a suitable host is planted
- spores will swim to the roots, often being attracted by root exudates
- spores enter the root and colonize it; in the process they kill the roots and feed on the dead tissue
- spores formed in the dead roots are released as the roots decompose
IPM Recommendations
- Avoid introduction of pathogens into the garden by cleaning tools and planting healthy, disease-free plants.
- Plant trees and shrubs in well-drained soils.
- Plant Phytophthora-resistant plant species if the disease is present in the soil or where a plant has previously died from Phytophthora infection.
- Infected plants should be removed with as much of the roots as possible and disposed of in the trash.