Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Elm > Sticky substance on leaves
Elm > Leaves > Sticky substance on leaves
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Woolly Elm Aphid
Eriosoma americanum, E.lanigerium and E. rileyi
- Produces honeydew from the aphid feeding, look for sooty mold on leaf surfaces or twigs
- Severe infestation can twist and curl leaves; leaves can yellow; branches can dieback
- Colonies on wood are covered by a white waxy or cottony material
- Adults are dark colored (reddish, brown, purplish), tiny size (1/16 to 5/32 inch)
- Preferred hosts are American and slippery elm
- More information on Woolly Elm Aphid
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European elm scale
Gossyparia spuria
- Excrete honeydew so leaves and branches may be covered by sooty mold
- Yellow leaves on lower branches
- Heavy infestations cause premature leaf drop and dieback of branches
- Dark gray oval body outlined by white wax
- Found mainly on American and rock elm
- More information on European elm scale
