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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous > Basswood/Linden > Dots, spots or blotches on leaves

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Basswood/Linden > Leaves > Dots, spots or blotches on leaves

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  • Image: Basswood lacebugs 1
  • Image: Basswood lacebugs 2
  • Image: Basswood lacebugs 3

Basswood lacebugs
Gargaphia tiliae

  • Needle-like mouthparts cause white or yellow speckled or pinprick discolorations that are visible on upper leaf surfaces
  • Defoliation can occur when trees are severely infested
  • Lace bugs are up to 1/5 inch long; light colored bodies; intricate, lacy wings
  • More information on Basswood lacebugs
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  • Image: Basswood leafminer 1
  • Image: Basswood leafminer 2
  • Image: Basswood leafminer 3

Basswood leafminer
Baliosus ruber

  • Larvae feed in between leaf surfaces, creating blotch-like mines
  • Mines are whitish or opaque at first but eventually turn brown
  • Damage caused by the beetle larvae
  • More information on Basswood leafminer
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  • Image: Linden leaf blotch 1
  • Image: Linden leaf blotch 2

Linden leaf blotch
Didymosphaeria petrakiana

  • Brown to blackish leaf blotches with fingerlike projections from margin
  • A yellow halo may develop around the leaf blotch or the entire leaf may yellow and fall off
  • Leaf spots appear in mid to late summer
  • Highly infected trees will lose nearly all infected leaves by early fall
  • More information on Linden leaf blotch
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  • Image: Powdery mildew 1
  • Image: Powdery mildew 2

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: 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: Euonymus scale 1

Euonymus scale
Unaspis euonymi

  • Feed by removing sap from leaves and twigs creating yellowish spots on leaves
  • Severe infestations lead to branch death and defoliation
  • Female scales are brownish, oblong shaped and found on twigs; immature males are white, linear shaped, fuzzy and found on leaves
  • More information on Euonymus scale
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  • Image: Introduced basswood thrips 1
  • Image: Introduced basswood thrips 2
  • Image: Introduced basswood thrips 3

Introduced basswood thrips
Thrips calcaratus

  • Buds are attacked resulting in bud drop or deformed, ragged appearance of new leaves in spring
  • Defoliation usually occurs when infestation is high resulting in a thin canopy
  • Typically a forest pest, usually not a landscape problem
  • American basswood is primary host
  • More information on Introduced basswood thrips

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