(UPDATED 2:37 p.m.) A new study from researchers at the University of California-Berkeley casts doubt on the practice of removing non-crop vegetation as a way to reduce field contamination of fresh produce by pathogens spread by animals.
The study, published by the journal Proceedings of the National Academy of Sciences, is available online.
Scott Horsfall, CEO of the California Leafy Green Marketing Agreement, said although the study has limitations — the data came from only company — it could help growers.
“We are always in favor of research that helps us better understand the risk of contamination, and if there is useful information here we want to make the most of it,” he said Aug. 11.
While the Leafy Greens Marketing Agreement requires buffer zones as a good agricultural practice, he said it does not require farmers to remove vegetation from those buffers.
“The LGMA encourages growers to engage in co-management practices, and this study adds important new information for consideration,” Horsfall said.
The practice of removing non-crop vegetation was implemented in response to a 2006 outbreak of E. coli in packaged spinach that killed three and sickened hundreds, according to a news release about the study.
The release said the E. coli strain in the 2006 outbreak was found around the farm and in the feces of cattle and wild pigs close to the farm, but the particular cause of the outbreak was never officially determined.
“Wildlife took much of the blame for that outbreak, even though rates of E. coli in wildlife are generally very low,” study lead author Daniel Karp, a NatureNet postdoctoral research fellow in UC-Berkeley’s Department of Environmental Science, Policy and Management and The Nature Conservancy, said in the release. “Now, growers are pressured by buyers to implement practices meant to discourage wildlife from approaching fields of produce. This includes clearing bushes, plants and trees that might serve as habitat or food sources for wild animals. Our study found that this practice has not led to the reductions in E. coli and Salmonella that people were hoping for.”
The study found that diverse habitats around fresh produce fields can boost bee populations and help the yields of pollinated crops, according to the release.
“There have also been studies that suggest that a landscape with diverse plant life can filter out agrichemical runoff and even bacteria,” study senior author Claire Kremen, a UC-Berkeley professor of environmental science, policy and management, said in the release. “Changing this dynamic shouldn’t be taken lightly.”