WSU Extension

Hortsense

Pine
 
Disease
Armillaria root rot 
Dwarf mistletoe 
Elytroderma needle cast 
Lophodermella needle cast 
Lophodermium needle cast 
Phytophthora root rot 
Western gall rust 
White pine blister rust 
Insect
Coneworms 
Eriophyid mites 
European pine shoot moth 
Mountain pine beetle 
Pandora moth 
Pine aphid 
Pine bark adelgid 
Pine butterfly 
Pine needle scale 
Pine needle sheathminer (Pine sheath miner) 
Sequoia pitch moth 
Spider mites 
White pine weevil 



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Caption: Phytophthora root rot infecting trunk
Photo by: R.S. Byther
  
Pine : Phytophthora root rot
(revision date: 4/23/2014)


Biology
Phytophthora root rot is usually a problem only in areas with poor drainage or where flooding occurs. The fungus attacks the roots, which rot and die. The infection moves up into the crown, where the cambium (soft inner bark) turns reddish-brown instead of the normal greenish-white. Older trees may develop cankers on the trunk, possibly accompanied by split bark and oozing pitch. Lower branches wilt, turn brown, and die back. Younger trees are often killed outright, while infected mature trees may show wilting, branch dieback, or other signs of inhibited water and nutrient uptake. Phytophthora root rot on pines is mainly a problem in nurseries or other irrigated plantings.
Management Options


Non-Chemical Management
  • Prevent disease by planting only disease-free materials in noncontaminated soil.
  • Improve soil drainage by incorporating organic material or using raised beds.
  • Avoid soil compaction, which reduces drainage. Construction, heavy foot traffic, or machinery can cause soil compaction.
  • Remove and destroy all infected plants and plant debris.
  • Plant resistant species in infected areas. Pinus mugo var. mughus has been found resistant to Phytophthora cinnamomi and P. lateralis. Your county Extension agent or WSU Master Gardeners can provide additional information found in the PNW Disease Management Handbook.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Phytophthora root rot infecting trunk
Photo by: R.S. Byther