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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Arborvitae
> Patchy yellow to brown discoloration

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Arborvitae > Foliage > Patchy yellow to brown discoloration

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  • Image: Eastern Tent Caterpillar 1
  • Image: Eastern Tent Caterpillar 2
  • Image: Eastern Tent Caterpillar 3

Spruce spider mite
Oligonychus ununguis

  • Needles are mottled yellowish to reddish brown
  • Silk can be found between needles
  • Most common during spring and fall
  • Common on arborvitae, spruce and juniper
  • Mites are dark green to brown; very small, 1/50 inch long
  • More information on Spruce spider mite...
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  • Image: Fall Webworm 1
  • Image: Fall Webworm 2
  • Image: Fall Webworm 3

Fletcher scale
Parthenolecanium fletcheri

  • Small to moderate levels of feeding usually do not result in any visible symptoms
  • Heavily infested foliage turns yellow, becomes thin as needles drop prematurely
  • Large amounts of honeydew are produced, often resulting in the presence of sooty mold on branches, twigs and needles
  • Common on arborvitae, juniper and yew
  • Small, ¼ inch long, round, brown scales at bases of needles
  • More information on Fletcher scale...
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  • Image: Eastern Tent Caterpillar 1
  • Image: Eastern Tent Caterpillar 2
  • Image: Eastern Tent Caterpillar 3

Leaf blight
Didymascella thujina

  • Random sections of the foliage turn tan to reddish brown
  • Small black spots appear within discolored sections of the foliage in late summer-early fall
  • In severe cases lower branches may appear scorched
  • Most severe on lower branches
  • Most severe on densely planted trees or on trees where foliate remains wet or very humid
  • More information on Leaf blight...
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  • Image: Fall Webworm 1
  • Image: Fall Webworm 2
  • Image: Fall Webworm 3

Pestalotiopsis blight
Pestalotiopsis funerea

  • Foliage on tips of branches turns first yellow then dark brown
  • Small twigs may be killed
  • Black pinpoint sized spore producing structures on infected twigs and foliage
  • Common on plants stressed by winter injury, drought or other factors
  • Often most severe on lower branches of the tree
  • More information on Pestalotiopsis twig blight...

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