WSU Extension

Hortsense

Douglas Fir
 
Disease
Armillaria root rot 
Laminated root rot 
Rhabdocline needle cast 
Rust 
Stem cankers 
Swiss needle cast 
Upper stem canker 
Yellow-green mottle syndrome 
Insect
Aphids 
Coneworms 
Cooley spruce gall adelgid 
Douglas fir needle midge 
Douglas fir tussock moth 
Douglas fir twig weevil 
Sequoia pitch moth 
Silverspotted tiger moth 
Spruce spider mite 



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Caption: Douglas-fir stem canker
Photo by: Unknown
  
Douglas Fir : Stem cankers
(revision date: 4/23/2014)


Biology
Stem cankers on Douglas fir are sunken and oval, occurring on branches or new shoots. Each canker is typically centered around a dead twig and can be small or up to 30" long or more. Cankers result in death of the stem or branch above the point of infection. Young, stressed trees are most susceptible. Infection often occurs following drought, frost damage, or mechanical injury. Two asexual fungi cause the disease. See also Douglas fir: Upper stem canker.
Management Options


Non-Chemical Management
  • Provide proper culture for trees to increase their disease resistance.
  • Avoid injuring trees to help reduce chances of infection.
  • Prune out infected shoots and branches to reduce spread of disease. Make pruning cuts well below cankers. Destroy infected material.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Douglas-fir stem canker
Photo by: Unknown
Caption: Douglas-fir lower stem canker
Photo by: Unknown