The GMO labeling debate is heating up, with the Grocery Manufacturers Association contributing $1.75 million last Friday to help defeat Initiative 522.

The initiative, which will be on the ballot this November, would require labeling of foods with GMO ingredients.

The latest contribution more than doubled the No campaign’s war chest to $3.3 million.

The Yes campaign has $3 million in cash, $950,000 of it from Dr. Bronner’s Magic Soaps.

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Dr. Bronner’s was a major contributor to a similar GMO labeling measure that was defeated last year in California. The soap company already has contributed more to the Washington measure than it did there.

The pro-labeling campaign in California raised more than $9 million, compared to $44 million for the anti-labeling side.

In California, Monsanto contributed more than $7 million, DuPont $4.9 million, Pepsico $2.1 million and Bayer CropScience more than $2 million.

Melissa Allison: 206-464-3312 or Twitter @AllisonSeattle.