Cherry plum just got checked.
This cherry plum is most likely being hit by aphids. The image shows clustered small insects along the stem/leaf junctions, and the sticky residue you noticed fits honeydew from sap-sucking pests. Aphids commonly make leaves look stressed or worsening over time even before major distortion shows up.
Reduce the aphid pressure today
Use gentle, reversible control first. The goal is to knock the aphids back before they spread further.
Also possible, but less likely
What would prove it
Recheck for active colonies
If the plant is still getting worse, inspect new growth closely. If aphids remain clustered, repeat water spray or consider a low-toxicity insecticidal soap only if needed and safe for the plant.
Turn this into a recovery case
One photo gives a diagnosis. Tracking proves whether the plant is recovering.
Don’t leave the diagnosis hanging 🌱
Save it now, then use the next photo to confirm if this was the right call.
Create account & save plant 🌱