What does Hester imagine she may see beneath/behind the footsteps of Chillingworth? Why is this significant?

Hester imagines that Chillingworth's footsteps blight the grass beneath them. This is significant because it illustrates the danger and evil intent she sees within him.

Hester gazed after him a little while, looking with a half fantastic curiosity to see whether the tender grass of early spring would not be blighted beneath him and show the wavering track of his footsteps, sere and brown, across its cheerful verdure.