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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Spruce > Witches’ Broom

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Spruce > Trunk or branches > Witches’ Broom

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  • Image: Eastern spruce dwarf mistletoe 1
  • Image: Eastern spruce dwarf mistletoe 2
  • Image: Eastern spruce dwarf mistletoe 3

Eastern spruce dwarf mistletoe
Arceuthobium pusillum

  • Witches’ brooms, a clump of small weak branches arising from one point on a larger branch, form in infected trees
  • Needles within the witches’ broom remain green, needles on the rest of the tree yellow and fall off, typically from the top of the tree down
  • Short (1/2 to 1 inch) brown to orange dwarf mistletoe stalks can be seen during the growing season but fall off after seed dispersal in August or September; this occurs only after 4 to 5 years of infection
  • Most common on black spruce in northern Minnesota; white spruce are also very susceptible
  • More information on Eastern spruce dwarf mistletoe...
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  • Image: Spruce needle rust 1
  • Image: Spruce needle rust 2
  • Image: Spruce needle rust 3

Spruce needle rust
Chrysomyxa spp.

  • Needles at the tips of the branches (current year needles) turn yellow
  • Pale orange to white tube like projections appear on infected needles in July or August and release powdery orange spores
  • Severely infected trees may have a tan to pinkish cast
  • Infected needles fall off in September
  • Some species of rust can cause witches’ brooms, a clump of small weak branches arising from one point on a large branch
  • More information on Spruce needle rust...

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