WSU Extension


Crown gall 
European canker (Nectria canker) 
Fire blight 
Pacific Coast pear rust 
Pear trellis rust 
Powdery mildew 
Pseudomonas blossom blast and dieback 
Stony pit 
Virus diseases 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Codling moth 
Cutworms and armyworms 
Pear psylla 
Pear slug (pear sawfly) 
Pearleaf blister mite 
San Jose scale 
Spider mites 

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Caption: Pear rust
Photo by: R.S. Byther
Pear : Pacific Coast pear rust
(revision date: 5/20/2014)

Pacific Coast pear rust is a fungal disease affecting pears, hawthorn, apple, crabapple, serviceberry, quince, and mountain ash. The alternate host is the incense cedar (Calocedrus decurrens), which develops witches' brooms. Infected fruits of pear are deformed and drop prematurely. On the surface of the fruit, yellowish spots with cup-shaped pustules develop. Leaves and green shoots may also be infected. Symptoms are most obvious after flowering and before July. For more information on pear rust diseases see Pear: Pear trellis rust.
Management Options

Non-Chemical Management
  • Avoid susceptible varieties such as 'Winter Nelis' and European and Oriental cultivars.
  • Collect and destroy fallen fruit beneath trees.
  • Plant resistant varieties such as 'Bartlett'.
  • Prune out and destroy rust-infected tissues in pears and alternate hosts.
  • Remove alternate hosts in the vicinity of pear trees, when practical.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Pear rust
Photo by: R.S. Byther
Caption: Pear rust
Photo by: R.S. Byther
Caption: Pear rust fruiting bodies
Photo by: C.R. Foss