The Grapes of Death
Les Raisins de la mort (original)
A young woman discovers that the pesticide being sprayed on vineyards is turning people into murderous lunatics.
Starring Marie-Georges Pascal, Félix Marten, Serge Marquand, Mirella Rancelot, Patrice Valota, Patricia Cartier, Michel Herval, Paul Bisciglia, Brigitte Lahaie, Olivier Rollin
Watch "The Grapes of Death" on Amazon released in 1978. It's a horror and drama movie, and has a rating of 6.1 out of 10 from Imdb which is usually fine for this kind of movie, and is currently only available for purchase or rent.