Skip to Left navigation Skip to Main content Skip to Footer

University of Minnesota Extension

Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous > Japanese tree lilac > Dead twigs or stems

Print Icon Email Icon Share Icon

Japanese tree lilac > Trunk/branches > Dead twigs or stems

1 of 4
  • Image: Fire Blight 1
  • Image: Fire Blight 2
  • Image: Fire Blight 3

Lilac borer
Podosesia syringae

  • Wilted young green shoots
  • Dead and/or broken stems above larvae feeding sites
  • Sawdust-like frass accumulates around entrance holes and on ground beneath
  • Larvae are creamy white, about 1" long with light brown head
  • Adults resemble paper wasps
  • More information on Lilac borer
2 of 4
  • Image: Codling moth 1
  • Image: Codling moth 2
  • Image: Apple Scab 3

Verticillium wilt
Verticillium dahliae

  • Leaves are small and yellowed in chronic infections
  • Leaves wilt, eventually turn brown and die in severe infections
  • Leaf symptoms are often seen on only one or a few random branches in the canopy
  • Dark olive to gray streaks are often visible in the sapwood if the bark is peeled back, appearing as rings or arcs in a cross section
  • Symptoms may develop over a single season, or over several years
  • More information on Verticillium wilt
3 of 4
  • Image: Black Rot 1
  • Image: Black Rot 2
  • Image: Black Rot 3

Oystershell scale
Lepidosaphes ulmi

  • Yellow leaves with heavy infestations
  • Heavy infestations can completely cover bark
  • Twig and branch dieback can occur when branches are heavily infested
  • Light to dark brown, elongated, 1/10 to 1/8 inch long, found feeding on branches
  • Damage occurs during summer
  • More information on Oystershell Scale
4 of 4
  • Image: White Rot 1
  • Image: White Rot 2
  • Image: White Rot 3

Lilac witches' broom
Candidatus Phytoplasma fraxini

  • Leaves in the entire canopy are pale green to yellow, leaf edges may turn brown
  • Witches' brooms, a cluster of numerous small weak shoots arising from one point, occur on branch ends and clustered along the base of the tree
  • Leaves on witches' broom are small, pale green to yellow and distorted
  • Individual branches die, the tree declines and eventually dies
  • More information on Lilac witches' broom

Don't see what you're looking for?