The research had expert wine drinkers compare the taste of organic versus non-organic wines grown in adjacent vineyards. Sixteen pairs of wines were sampled.
The wines were individually tested for the presence of 250 different pesticides.
The average (mean) was 293 ppb, which included the most widely used ones: 1. glyphosate based herbicides and 2. synthetic fungicides.
Tasters preferred the taste of non-pesticided wines 77% of the time, compared to wines raised with pesticides.
In addition, tasters were asked to evaluate the taste of individual pesticides diluted in water at the level of concentration that the substances were found in wine, so that the taste of the chemicals could be analyzed individually. Tasters reported the following tastesassociated with the different chemicals listed below:
In California, the most commonly used pesticides from this list are glyphosate (and Roundup) and boscalid, a bird and bee toxin commonly used as a fungicide. (Imidacloprid, the neonicotinoid that is commonly used on vineyards in California - and is a bird and bee toxin - does not show up on the study list as it is prohibited in the EU.)
Use these links to read a summary news article and the whole study.
If California were to repeat such a study, it might reflect the use of these top two pesticides for wines from the following regions, where glyphosate and boscalid are commonly used on wine grapes.