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