§ 709. Punitive provision. Any person who shall wilfully resist, prevent, impede, or interfere with any member of the board or any of its agents or agencies in the performance of duties pursuant to this article, or who shall in any manner interfere with the free exercise by employees of their right to select representatives in an election directed by the board pursuant to section seven hundred and five, shall be punished by a fine of not more than five thousand dollars or by imprisonment for not more than one year, or both.