Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Elm > Colored patches or bumps on branches or trunk
Elm > Trunk/Branches > Colored patches/bumps on branches/trunk
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Lichens
Several species
- Colorful patches on the bark of trunk and/or branches
- Can be wrinkled, in scalloped sheets, lace-like pads, bushy tufts, paint-like spots or splashes
- Forms can be flat against the bark surface or raised in leaf-like lobes, finger-like or hairy projections
- Colors may be shades of gray, green, blue, yellow, orange, or red
- More information on Lichens
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Oystershell scale
Lepidosaphes ulmi
- Heavy infestations can completely cover bark
- Feeding can cause foliage to yellow
- 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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European elm scale
Gossyparia spuria
- Yellow leaves on lower branches
- Heavy infestations cause premature leaf drop and dieback of branches
- Excrete honeydew so leaves and branches may be covered by sooty mold
- Dark gray oval body outlined by white wax
- Found mainly on American and rock elm
- More information on European elm scale
