SAN FRANCISCO — California voters will soon decide whether to require special labels for food made from genetically modified ingredients, in a closely watched test of consumer attitudes about the merits of genetically engineered crops.

Advocates collected more than half a million signatures supporting the stronger labeling requirements, and the secretary of state this week certified the measure for the state’s November ballot.

If it passes, California would be the first state to require labeling of such a wide range of foods containing genetically modified organisms, or GMOs.

The proposal would require most processed foods by 2014 to bear a label telling shoppers that they contain ingredients derived from plants whose DNA was altered with genes from other plants, animals, viruses or bacteria.

Many backers of similar labeling legislation in more than a dozen states say the intent is to give consumers more information about what they’re eating, and foster transparency and trust in the food system.