WSU Extension

Hortsense

Elm
 
Disease
Bacterial wetwood (Slime flux) 
Dutch elm disease 
Nectria canker 
Insect
Aphids 
Bark beetles 
Carpenterworm 
Elm leaf beetle 
Elm leafminer 
European elm scale 
Spiny elm caterpillar 



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Caption: Dutch elm disease
Photo by: C.R. Foss
  
Elm : Dutch elm disease
(revision date: 4/28/2014)


Biology
Dutch elm disease is a fungal infection transmitted by elm bark beetles. Bark beetles carry disease spores on their bodies and infect trees when they feed. Leaves above the infection site turn yellow and twigs die back, producing a characteristic "flagging" symptom. Premature leaf drop may occur. The infection spreads rapidly throughout the tree, plugging the vascular system and killing the entire tree in one to several years. Infected branches show streaking and discoloration of the outer layers of the wood when cut. The disease can overwinter in infected, dying, or dead trees, dead wood and stumps, and recently cut logs. The disease can also spread from infected to healthy trees through natural root grafts.
Management Options


Non-Chemical Management
  • Plant resistant elm varieties including 'Christine Buisman', 'Dynasty', 'Homestead', 'New Horizon', 'Pioneer', 'Regal', 'Urban', and 'Sapporo Autumn Gold'. Siberian elm (Ulmus pumila), Chinese elm (U. parvifolia), Japanese zelkova (Zelkova serrata), elm zelkova (Z. carpinifolia), and hackberry (Celtis sp.) are also resistant.
  • Bark beetles are attracted to injured trees. Avoid injury to trees during spring and summer.
  • Control bark beetles, which may attack weak or damaged trees.
  • Destroy freshly cut wood of beetle-infested trees or strip and destroy bark from logs.
  • Remove infected trees immediately.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Dutch elm disease
Photo by: C.R. Foss
Caption: Dutch elm disease streaking in sapwood
Photo by: C.R. Foss
Caption: Dutch elm disease synnema growth close-up
Photo by: C.R. Foss