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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Black Walnut > Leaves discolored white to yellow

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Black Walnut > Leaves > Leaves discolored white to yellow

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

Anthracnose
Gnomonia leptosyla

  • Circular brown lesions form on both sides of leaflets
  • Lesions are smaller than a pencil tip and surrounded by a yellow area
  • Infected leaves turn yellow, then brown on the margins, and eventually fall off
  • Smaller but similar spots form on nut husks, interfering with nut development and causing premature drop
  • More information on Walnut Anthracnose...
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  • Image: Walnut lacebug 1
  • Image: Walnut lacebug 2
  • Image: Walnut lacebug 3

Walnut lacebug
Corythucha juglandis

  • Feeds on undersides of leaves with needle-like mouthparts causing white or yellow speckled or pinprick discolorations on leaf surface
  • Black dots or specks (droppings) are on the underside of leaves
  • Heavy feeding can cause severe discoloration and leaf drop
  • Lace bugs are 1/8 to 1/4 inch long; light colored bodies; intricate, lacy wings
  • Damage is most noticeable in mid to late summer
  • More information on Walnut lace bug...
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  • Image: Leaf spot 1
  • Image: Leaf spot 2
  • Image: Leaf spot 3

Leaf spot
Mycosphaerella juglandis

  • Small black spots scattered across leaf
  • Dark brown veins and leaf tips are common due to many spots forming on leaf veins and leaf tips
  • As the disease progresses, leaves yellow and fall off
  • In mid-summer leaves appear yellow from a distance
  • Occurs on black walnut and butternut
  • More information on Leaf spot...

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