Piešťany Grape and Wine Festival in Piešťany
No independently verifiable event specifically named a 'Piestany Grape and Wine Festival' could be confirmed. Targeted Slovak Wikipedia search for a Piestany grape-harvest or wine festival (vinobranie) returned no matching results, though grape and wine harvest festivals are a common civic tradition across many Slovak towns.
Piestany is best known internationally as Slovakia's leading spa town, and its confirmed festival identity centers on Music festival Piestany, an international classical music event with a documented history under several prior names.