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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Spruce > Sap on trunk or branches

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Spruce > Trunk or branches > Sap on trunk or branches

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  • Image: Cytospora canker 1
  • Image: Cytospora canker 2
  • Image: Cytospora canker 3

Cytospora canker
Leucostoma kunzei

  • Needles on one or more branches turn completely brown or purplish brown then fall off
  • Scattered dead branches occur throughout the tree, often starting on the lower branches and then spreading upward
  • Clear to white resin encrusted cankers on infected branches
  • Common on Colorado blue spruce, or very stressed spruces
  • More information on Cytospora canker...
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  • Image: Pitch mass borer 1
  • Image: Pitch mass borer 2

Pitch mass borer
Synanthedon pini

  • Pitch masses with frass (sawdust mixed with droppings) on trunk
  • Larger trees preferred, medium trees can also be attacked
  • Needles can yellow
  • Caterpillar has a light brown or yellowish-brown head and cream to greenish-yellow body
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  • Image: Spruce beetle 1
  • Image: Spruce beetle 2
  • Image: Spruce beetle 3

Spruce beetle
Dendroctonus rufipennis

  • Found in stands white spruce in northern Minnesota, particularly along the North Shore
  • Prefers larger trees, 12 inch diameter trees or larger
  • Needles discolor yellowish green to reddish brown
  • Reddish brown sawdust around exit holes and on the bark and on the ground
  • Pitch tubes develop around exit holes
  • Trees eventually die
  • Adult beetles are 1/4 inch long and black to reddish-brown; larvae are small, white legless grubs

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