Now they face potential competition if Proposition 19passes in California next week, legalizing marijuana for recreational purposes.

"It's no surprise...that the California Beer & Beverage Distributors have come out against Proposition 19," writes wine blogger Tom Wark, in a post titled "'Booze Dollars' vs. 'Dope Dollars'".

Wark writes that the alcoholic beverage industry isn't against legalizing pot in principle. Instead, he says, they claim Prop 19 is badly written. "I don't believe them because I know they are smart, I know they spend money to protect their financial interests and I know that beer will lose sales to dope. And so do they."

Wark believes that wine will not be as threatened by legal pot as other beverages will be.