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Birch > Leaves > Spots or blotches on leaves

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  • Image: Birch erineum or velvet gall 1
    Credit: J. Hahn, University Of Minnesota
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green arrowBirch erineum or velvet gall

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  • Image: Birch leafminer 1
    Credit: B. Kunkel, Univ. of DE, Bugwood.org
  • Image: Birch leafminer 2

    Credit: J. Hahn, University Of Minnesota

  • Image: Birch leafminer 3

    Credit: J. Albers, MN Dept. of Natural Resources, Bugwood.org

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green arrowBirch 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
    Credit: J. O'Brien, USDA Forest Service, Bugwood.org
  • Image: Sooty mold 2

    Credit: R. Koetter, University Of Minnesota

  • Image: Sooty mold 3

    Credit: W. Jacobi, Colorado State University, Bugwood.org

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green arrowSooty 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
    Credit: C. Behrendt, University Of Minnesota
  • Image: Birch anthracnose or leaf spot 2

    Credit: P. Bachi, Univ. of KY Research & Education Center, Bugwood.org

  • Image: Birch anthracnose or leaf spot 3

    Credit: P. Bachi, Univ. of KY Research & Education Center, Bugwood.org

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green arrowBirch 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
    Credit: M. Grabowski, University Of Minnesota
  • Image: Birch rust 2

    Credit: M. Grabowski, University Of Minnesota

  • Image: Birch rust 3

    Credit: M. Grabowski, University Of Minnesota

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green arrowBirch 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
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  • Image: Powdery mildew 1
    Credit: M. Grabowski, University Of Minnesota
  • Image: Powdery mildew 2

    Credit: A. Kunca, National Forest Centre - Slovakia, Bugwood.org

  • Image: Powdery mildew 3

    Credit: A. Kunca, National Forest Centre - Slovakia, Bugwood.org

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green arrowPowdery 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
    Credit: R. S. Kelley, VT Dept. of Forests, Parks and Recreation, Bugwood.org
  • Image: Birch skeletonizer 2

    Credit: R. S. Kelley, VT Dept. of Forests, Parks and Recreation, Bugwood.org

  • Image: Birch skeletonizer 3

    Credit: R. S. Kelley, VT Dept. of Forests, Parks and Recreation, Bugwood.org

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green arrowBirch 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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