No person shall apply, within the affected area as set forth in section 321.3, any sprays of 2,4-D, 2,4-5-T or MCP in any chemical form whatever at a rate of application less than 15 gallons per acre nor at a nozzle pressure exceeding 40 pounds per square inch nor within 100 feet of any grape vineyard located, in whole or in part, within the affected area.