In November, Californians will vote on Proposition 37, a requirement to label genetically engineered foods, a prospect the pesticide and processed food industries are not happy about. According to an analysis of campaign finance reports by Right To Know, an advocacy group promoting the ballot initiative, chemical and processed food companies recently contributed nearly $10 million to “No on 37,” which describes itself as “a coalition of family farmers, grocers, small businesses, and food producers” against food labeling.

Funding from pesticide and seed companies now tops $7 million, with the biggest contributions from Dupont Pioneer, Bayer Crop science and BASF Plant Science. Genetically engineered crops are designed to be resistant to toxic pesticides and herbicides patented by these companies. But the resistant seeds have spurred the growth of “super weeds,” which require even more herbicide. In 2008, GE crop acres required over 26 percent more pounds of herbicides per acre than acres planted to conventional varieties. It’s not just the weeds that are mutating — “super insects” are also starting to become a serious problem. Chemical companies profit enormously from this GE arms race, which gives farmers little choice but to buy bigger, more poisonous batches of pesticides and new strains of seeds engineered to withstand them.

Besides the chemical industry, companies including Coca-Cola, PepsiCo, Nestle USA, General Mills and ConAgra are pouring money into defeating the labeling requirement. If California passes the measure, these companies’ profits could suffer from a warning label driving consumers away. Proposition 37 could also take the GMO-labeling movement national, which has so far stalled in 20 states in spite of support from 91 percent of Americans. The Food and Drug Administration has said labels are unnecessary because GE foods have not been shown to be harmful. Many other countries, including Japan, Australia, China and the European Union, already require labels on GE food.