Skip to Main navigation Skip to Left navigation Skip to Main content Skip to Footer

University of Minnesota Extension
www.extension.umn.edu
612-624-1222

Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Pine > Sunken, cracked or discolored areas

Print Icon Email Icon Share Icon

Pine > Trunk/Branches > Sunken, cracked or discolored areas along branches or trunk

1 of 3
  • White pine blister rust 1
  • White pine blister rust 2
  • White pine blister rust 3

White pine blister rust
Cronartium ribicola

  • All needles on one or several branches die and turn completely reddish-orange
  • Young cankers are elliptical, bark appears swollen and discolored yellowish orange
  • Older cankers exude large amounts of white sticky resin and have cracked bark
  • In early spring, orange-yellow blisters appear on the bark of cankers that are 2 or more years old
  • In summer, yellow-orange sticky liquid droplets form in cankers 3 years or older
  • Only white pine and other five needled pines can be infected
  • More information on White pine blister rust...
2 of 3
  • Sweetfern rust 1
  • Stalactiform 2
  • Comandra 3

Comandra, Stalactiform or Sweetfern rust
Cronartium comandrae, Cronartium coleosporioides, and Cronartium comptoniae

  • When severe, canopy is thin, has poor growth, needles yellow, turn brown and die
  • On young stems or branches, infection may appear as a swollen, elliptical area
  • Infection develops into a long, flattened, resin soaked canker on the main trunk
  • Sweetfern rust cankers frequently occur near the soil level and grow up to 6 ft. long
  • Stalactiform rust cankers grow up to 25 ft. long along the main trunk
  • Comandra rust cankers occur on the main trunk and rarely grow over 4 ft. long
  • Ridges of wound wood may be present along edges of the canker
  • Pale yellow blisters of powdery spores break through cracks in bark in spring, sticky orange drops form along canker edges in late summer to fall
  • On young stems or branches, infection may appear as a swollen, elliptical area
  • Jack and ponderosa pine most severely affected, but many 2-3 needle pines are susceptible
  • Differentiation between the 3 species is most accurate with a lab analysis
  • More information on Comandra, Stalactiform or Sweetfern rust...
3 of 3
  • Diplodia shoot blight 1
  • Diplodia shoot blight 2
  • Diplodia shoot blight 3

Diplodia shoot blight
Diplodia pinea

  • New needles are brown, short and often glued together with resin
  • Cankers are resin coated flattened areas on branches
  • Needles and branch beyond canker turn brown and dies
  • Tiny, black, pimple-like fungal structures on dead needles and pine cones
  • Infected shoots and dead branches occur throughout the tree but most commonly in lower canopy
  • Cankers and dead needles can appear rapidly after wounding from hail, drought or other stress
  • Olive to dark brown streaking in sapwood below cankers
  • Common on Austrian, red and Scots pine
  • More information on Diplodia shoot blight...

Don't see what you're looking for?

  • © Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy