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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Black Walnut > Dark spots or blotches

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Black Walnut > Nuts > Dark spots or blotches

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  • Image: Husk maggots 1
  • Image: Husk maggots 2
  • Image: Husk maggots 3

Husk maggots
Rhagoletis spp.

  • Larvae (maggots) feed inside the husk during mid-summer
  • Larvae feeding causes husks to become slimy, dark and stick to the shell
  • Do not harm nutmeat but fruit becomes unappealing and difficult to handle
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  • Image: Anthracnose 1
  • Image: Anthracnose 2
  • Image: Anthracnose 3

Gnomonia leptosyla

  • Leaflets have circular brown spots surrounded by yellow tissue
  • Infected leaves turn yellow, then brown on the margins, curl and eventually fall off
  • Dark brown to black spots or blotches form on nut husks
  • Nuts drop prematurely
  • More information on Walnut Anthracnose

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