Q.Lilac Bush and black spots
Planted a new lilac bush 5 days ago. Originally, noticed some black spots on the leaves so removed those leaves and planted the bush. 5 days later the leaves keep getting black spots. Is this a fungus or insect problem? I don’t see any insects on the leaves. Should I return the bush or is it fixable?
This could very well be both issues. A stressed plant for either an infestation or disease can be attacked with multiple issues.
The black spots, that you are spreading and the distortion in the leaves are indicators of a bacterial leaf spot and or insects.
I would absolutely send this plant back for a replacement.
Discard any plant material that has dropped from the tree to avoid contaminating any other plants in your yard.
Here are some links to help you.