Phyllis A. Whitney: The Vanishing Scarecrow

The Vanishing Scarecrow by Phyllis A. Whitney was published by Signet in January 1975. Jean and her mother inherited Rainbow Island, an amusement park, from her uncle and they wanted to keep it running but someone was trying to shut them down by scaring the customers and ruining the exhibits.

This is a suitably scary cover by Allan Kass with the heroine teen  walking through a field of scarecrows and one about to grab her! It's closer to the adult gothic covers with only the heroine and the ubiquitous mansion with a glowing light inside!