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

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Maple > Leaves > Spots or blotches on leaves

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  • Image: Anthracnose 1
  • Image: Anthracnose 2
  • Image: Anthracnose 3

Anthracnose
Discula campestris, D. umbrinella, Aureobasidium
apocryptum, Colletotrichum gloeosporioides

  • Mature leaves have irregularly shaped tan, brown or black leaf spots found along leaf veins; may be curled if severely infected
  • Young leaves turn brown to black, shriveled or curled
  • Lower, interior branches are most affected
  • Damage occurs in wet weather in early spring as leaves are expanding
  • More information on Anthracnose...
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  • Image: Tar spot 1
  • Image: Tar spot 2
  • Image: Tar spot 3

Tar spot
Rhytisma spp.

  • Tar spots may be one large black raised spot (1/4-1/2 inch wide) or many small spots clustered together, and often have a yellow halo
  • Leaf spots are initially pale green to yellow and are easily overlooked
  • In late summer a raised thick black tar-like spot develops on the leaves
  • Most common on lower branches, near the center where humidity levels are the highest
  • More information on Tar spot...
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  • Image: Phyllosticta leaf spot 1
  • Image: Phyllosticta leaf spot 2
  • Image: Phyllosticta leaf spot 3

Phyllosticta leaf spot
Phyllosticta minima

  • Well-defined, round to irregular spots on leaves with a light-colored center surrounded by a reddish or purplish halo
  • Tiny black spots may be visible in the light colored center of the spot
  • Discolored areas may eventually merge together to create larger dead areas between the leaf veins
  • More information on Phyllosticta leaf spot...
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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
  • Lower shaded leaves are most commonly affected, common on small understory trees
  • Damage is common in spring or fall
  • More information on Powdery mildew...
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  • Image: Sooty mold 1
  • Image: Sooty mold 2

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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