Two years ago I planted two forsythia bushes that I had purchased from my local Home Depot. They have been growing slowly but this Spring one of the bushes has developed weird, coiled/curled branches (see attached). Can you tell me what's going on with it?
Alpena County Michigan
This is probably herbicide injury. Some garden herbicides can drift on the wind and injure plants. The injury could have been from this year, or from last fall. Glyphosate or 2,4-D are two examples that can cause injury, there are more. Sometimes an insect gall can cause distorted growth.
You can submit samples and pictures to MSU Plant Diagnostic lab for confirmation. Include a picture of the whole shrub, and close up of the leaves-
Here is a reference for you-
I hope this helps! Thank you.