No brewery or beer importer shall increase the prices charged any wholesale beer licensee for beer except by written notice to the wholesaler signed by an authorized officer or agent of the brewery or beer importer, which notice shall contain the amount and effective date of the increase. A copy of the notice shall be sent to the Board and shall be treated as confidential information, except in relation to enforcement proceedings for violation of this section. No increase shall take effect prior to thirty calendar days following the date on which the notice is postmarked. The Board may authorize such price increases to take effect with less than the aforesaid thirty-calendar-day notice if a brewery or beer importer so requests and demonstrates good cause therefor.