Bayer CropScience has advised wine grape growers not to use its Moon Privilege (or Luna Privilege) fungicide, pending an investigation into a possible connection between spraying of the chemical compound and reported crop damage.

Some wine grape growers are said to have reported deformed leaves and lower yields from their crops this year, and according to the Sunday newspaper Schweiz am Sonntag, some Swiss growers, who blame the fungicide, are demanding compensation from Bayer. One grower told the paper that a potential loss of 10% of the Swiss wine grape harvest looms.

In a notice on its website, Bayer pointed to “atypical symptoms” in vines where the fungicide has been deployed in 2014. “As long as the cause of this change in the grape vines remains unexplained, we recommend for precautionary reasons not to use Luna Privilege for wine growing,” Bayer said, adding that it “regrets” the situation and is doing “everything necessary” to discover the cause.

Reports said Bayer had acknowledged in a letter to growers a "high probability" of a connection between the fungicide and damage to the 2015 harvest. It also quoted a viticulturist grower in the northern Swiss canton of Aargau as saying damage could run up to a triple-digit Swiss franc sum.

Moon / Luna Privilege is used to protect grapes against Botrytis cinerea, or gray mold, Botrytis rot or gray mold-rot. The fungicide contains fluopyram, a chemical discovered in 1999 that is active against a number of plant diseases.

Agricultural scientists in Norway as well as in the US Midwest are said to have warned that there is a high potential for runoff several months after application of the product and a threat of surface water and groundwater contamination. In New Zealand, spraying has been adapted to protect bees.

In 2014, Bayer forecast sales of more than €250 million for its Luna group of products, which were launched in 2012 and are used for fruit and vegetable crops.