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

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Poplar > Leaves > Dots, spots or blotches on leaves

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  • Image: Venturia shoot blight 1
  • Image: Venturia shoot blight 2
  • Image: Venturia shoot blight 3

Venturia shoot blight (Scab)
Venturia spp.

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  • Image: Leaf spot and canker blights 1
  • Image: Leaf spot and canker blights 2
  • Image: Leaf spot and canker blights 3

Leaf spot and canker blights
Marssonina spp., Septoria spp., Colletotrichum

  • Irregular dark spots (angular to round) to large blotches on leaf surface
  • Severe infestations may lead to leaf yellowing full defoliation by late summer
  • Lower branches are infected first
  • Dark, sunken cankers can develop on stems of Septoria infected
  • More information on Leaf spot and canker blights
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  • Image: Poplar rust 1
  • Image: Poplar rust 2
  • Image: Poplar rust 3

Poplar rust
Melampsora medusae

  • Yellow to orange spore pustules on leaf underside, yellow spots on leaf surface
  • Powdery orange to yellow spores can be seen if lower leaf surface is rubbed with a white cloth
  • Severely infected leaves dry, shrivel and fall prematurely
  • Lower branches are first infected
  • In severe infestations, trees can loose all leaves within a few weeks
  • More information on Poplar rust
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  • Image: Whitemarked tussock moth 1
  • Image: Whitemarked tussock moth 2
  • Image: Whitemarked tussock moth 3

Whitemarked tussock moth
Orygia leucostigma

  • Young larvae windowpane feed (i.e. feed on one layer of leaf tissue between veins) giving them a lacelike
  • Older larvae consume entire leaves except the midrib and large veins
  • Caterpillars have a red-orange head with two sets of black tufts near the head; yellowish hairy body with distinct tufts of hair resembling a toothbrush on top of the body
  • Full grown larvae are 1 ¼ inches long
  • Damage by 2 generations, first from May to June and a second one from August to September
  • More information on Whitemarked tussock moth
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  • Image: Cottonwood leaf beetle 1
  • Image: Cottonwood leaf beetle 2
  • Image: Cottonwood leaf beetle 3

Cottonwood leaf beetle
Chrysomela scripta

  • Larvae windowpane feed, i.e. feed on the upper leaf surface between the veins
  • Adults eat leaf margins and create "shot-holes" in leaf tissue
  • Defoliation can occur when populations are high
  • Adults are ¼ inch long with yellow and black stripes
  • Larvae are black when young and have 2 white dots on either side
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  • Image: Aspen blotch miner 1
  • Image: Aspen blotch miner 2

Aspen blotch miner
Phyllonorycter tremuloidiella

  • Mines are whitish or opaque at first but eventually turn
  • Larvae feed between leaf surfaces create blotch-like mines
  • Common in late summer
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  • Image: Poplar lace bug 1
  • Image: Poplar lace bug 2
  • Image: Poplar lace bug 3

Poplar lace bug
Corythucha elegans

  • White or yellow speckled or pinprick discolorations on upper leaf
  • Can look bleached when infestations are more severe
  • Lace bugs are up to 1/4 inch long; light colored bodies with dark colored spots; intricate, lacy wings
  • More information on Poplar lace bug

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