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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Birch > Spots or blotches on leaves

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Birch > Leaves > Spots or blotches on leaves

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  • Image: Birch erineum or velvet gall 1

Birch erineum or velvet gall

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  • Image: Birch leafminer 1
  • Image: Birch leafminer 2
  • Image: Birch leafminer 3

Birch leafminer
Fenusa pusilla

  • Feed inside newly developing leaves forming opaque to light green kidney-shaped discolorations
  • Smaller mines may coalesce into larger mines
  • Insects and/or black frass visible inside leaves if held up to light
  • Mines eventually turn brown
  • Damaged leaves evenly distributed throughout tree
  • Larvae are yellowish white, legless, and up to ¼ inch long
  • Preferred hosts are paper birch and gray birch
  • More information on Birch leafminer
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  • Image: Sooty mold 1
  • Image: Sooty mold 2
  • Image: Sooty mold 3

Sooty mold

  • Black, brown, or gray soot-like covering on leaf surfaces, or twigs
  • Sticky, shiny secretions on leaves from sap-sucking insects (aphids, leaf hoppers, psyllids, etc.)
  • Insects or signs of insect damage (distorted, pin-prick feeding marks, etc.) may be seen on leaves above the worst affected moldy areas
  • More information on Sooty mold
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  • Image: Birch anthracnose or leaf spot 1
  • Image: Birch anthracnose or leaf spot 2
  • Image: Birch anthracnose or leaf spot 3

Birch anthracnose or leaf spot
Cryptocline betularum, Discula betulina and others

  • Leaf spots may be 1/8th to 3/8th inch brown spots to large brown blotches surrounded by yellow tissue (C. betularum)
  • Leaf spots may be 1/8th inch wide brown rings with a light center surrounded by yellow tissue (D. betulina)
  • Infected leaves fall from tree even if still partly green
  • Leaves on lower branches most affected
  • Common in years with wet rainy spring weather
  • More information on Birch anthracnose
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  • Image: Birch rust 1
  • Image: Birch rust 2
  • Image: Birch rust 3

Birch rust
Melampsoridium betulinum

  • Angular yellow leaf spots turn brown in the center with age
  • Raised yellow to orange pustules form on the lower surface of leaf spots midsummer and may release powdery orange spores
  • Severe infection can cause leaves to turn brown and fall off prematurely
  • Occurs in cool, damp weather
  • More information on Birch rust
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  • Image: Powdery mildew 1
  • Image: Powdery mildew 2
  • Image: Powdery mildew 3

Powdery mildew
Phyllactinia guttata

  • White or gray powdery mats, resembling talcum powder, occur
    in spots, blotches or coat leaves
  • Leaves may become deformed and turn yellow and die in
    severe infestations
  • Common on lower leaves or leaves that are shaded
  • Commonly seen in spring or fall
  • More information on Powdery mildew
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  • Image: Birch skeletonizer 1
  • Image: Birch skeletonizer 2
  • Image: Birch skeletonizer 3

Birch skeletonizer
Bucculatrix canadensisella

  • Feeds on underside of leaf between the veins, giving the leaf
    a lacelike appearance
  • Leaves brown in late summer and can fall prematurely
  • Caterpillars are approximately ¼" long; whitish to yellowish
    in color
  • Damage occurs when larvae are active in mid-summer
  • Preferred hosts are paper birch

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