Heavily shaded hazelnut orchards may discourage salmonella from lingering on the ground, but the conclusions for growers remain uncertain, according to an orchard researcher.

Ground temperatures in heavily shaded hazelnut orchards appear to fall below the temperature range in which salmonella thrives, compared to orchards with less shade cover, said Bruce Lampinen, a tree nut specialist with the University of California Cooperative Extension.

Lampinen presented his findings during a recent summer tour of the hazelnut industry in Oregon’s Willamette Valley, which was organized by the Nut Growers Society.

The results in Oregon hazelnut orchards were greatly different than in California almond and walnut orchards, where heavy shade cover seems to improve conditions for salmonella, he said.

Those crops are grown in warmer regions where heat can discourage the pathogen, so heavy shade cover in California actually “pushes” temperatures into the ideal range for salmonella, Lampinen said. In cooler Oregon, temperatures were pushed below that range.

However, the findings are based on limited data and need more s