WSU Extension

Hortsense

Juniper
 
Disease
Dieback 
Magnesium deficiency 
Pear trellis rust 
Phomopsis twig blight 
Phytophthora root rot 
Rust 
Insect
Aphids 
Cypress tip moth 
Juniper scale 
Juniper tip midge 
Juniper webworm 
Leafminers 
Spruce spider mite 



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Caption: Juniper rust
Photo by: R.S. Byther
  
Juniper : Rust
(revision date: 4/23/2014)


Biology
Several types of rusts infect junipers. The alternate hosts for most of the rusts are in the rose family, including plants such as hawthorn, cotoneaster, and apple. Infected junipers develop round or elongate galls on the branches. The galls may be greenish-brown, tan, or reddish in color. Twigs above the galls may die back or may form witches' brooms. In the spring, the galls typically produce reddish fungal fruiting bodies which may appear slimy or gelatinous when wet. The fungus produces spores on the alternate hosts in mid to late summer. Pear trellis rust is also found on ornamental junipers.
Management Options


Non-Chemical Management
  • Avoid overhead watering. Moisture is necessary for infection to occur.
  • Remove infected leaves on alternate host plants such as apple or hawthorn, or remove suspected alternate hosts in the vicinity of the junipers.
  • Prune and destroy galls in junipers before the fruiting period in the spring.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Juniper rust
Photo by: R.S. Byther