Prior to the beginning of each marketing season, or as soon as possible thereafter, the commission shall establish assessment rates for the marketing season, as follows:

1. (a) An annual assessment on producers of not less than one hundred dollars ($100) and not more than one thousand dollars ($1,000), as determined by the commission, based on the number of tons of winegrapes marketed during the preceding marketing season.
2. (b) In addition, producers shall pay an assessment not less than one dollar ($1) and not greater than twelve dollars ($12) per ton of winegrapes marketed by producers. In the discretion of the commission, the producer assessment may be established as a percent of the gross dollar value received by producers for winegrapes rather than on a per ton basis. The assessment shall be established on a sliding scale that decreases the assessment by two dollars ($2) per ton, or the percentage equivalent if the assessment is a percent of gross dollar value, for every 500 tons of winegrapes marketed by producers in excess of 1000 tons.
3. (c) An annual assessment on vintners of not less than three hundred fifty dollars ($350) and not more than seven thousand five hundred dollars ($7,500), as determined by the commission, based on the number of tons of winegrapes processed and marketed by vintners during the preceding marketing season.
4. (d) In addition, vintners shall pay an assessment not less than one dollar ($1) and not greater than twelve dollars ($12) per ton of winegrapes processed by vintners for which an assessment has not already been paid by a producer. The assessment shall be established on a sliding scale that decreases the assessment by two dollars ($2) per ton for every 500 tons of winegrapes processed by vintners in excess of 1000 tons.
5. (e) An assessment greater than the amount provided for in this section may not be charged unless and until a greater amount is approved by a majority of the commission and by eligible producers and vintners pursuant to the referendum procedures specified in Section 78903.