WSU Extension

Hortsense

Pine : Western gall rust
(revision date: 4/23/2014)


Biology
Western gall rust affects primarily two- and three-needle pines, including shore, lodgepole, mugo, Scotch, Austrian, and ponderosa pines. This fungal disease causes small to large round or pear-shaped galls on infected twigs, branches, or trunks. The galls persist and enlarge each year. Branch tips beyond the galls become stunted and bushy and may die. In the spring, two-year-old and older galls are covered with orange or yellow-orange spores, which cause new infections on young shoots of susceptible trees. Large galls can weaken the trunk or major limbs, making them highly susceptible to breakage.
Management Options

Non-Chemical Management
  • Prune out and destroy galls from infected trees.
  • If the gall occurs on the trunk, it may be possible to prune the tree back and train a new leader to replace the diseased portion. However, it may be necessary to remove the tree for safety's sake.
  • Remove infected trees from pine stands.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

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Caption: Western gall rust
Photo by: R.S. Byther
Caption: Western gall rust
Photo by: R.S. Byther