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 substantiation before any recommendations can be offered to growers, he said.
Hazelnut farmers also discussed various methods of discouraging animals from entering their orchards, as they can create food safety concerns and reduce yields by eating foliage or nuts.
Deer fencing is highly effective but expensive, though costs will depend on how much labor a grower can do himself, said Tim Aman, a field representative for the Hazelnut Growers of Oregon cooperative.
A repellent called Plantskydd also works, but farmers must reapply the substance after rain washes it off leaves, he said.
Rather than treating an entire orchard, growers can try spraying several rows of trees along the perimeter to discourage deer from venturing farther inside, Aman said.
A farmer at the meeting said cougar and coyote urine can also deter deer as long as you apply it in areas that the animals are known travel.
For squirrels, which can consume large quantities of nuts, farmers recommended shooting them at sunrise, when they're most active.
Some farmers said placing Conibear traps near burrows is effective, while others recommended using bait treated with an anti-coagulant rodenticide, like Ramik Brown.
Farmers should look for signs of animal presence and document their efforts to deter them from lingering in orchards, said George Kaufman, who specializes in food safety at the Agricare farm management company.
Recording a farm’s food safety measures is generally encouraged if growers want to be certified for “good agricultural practices” by third-party auditors, which is increasingly demanded by food companies, he said.
“If things aren't documented, it didn't happen,” Kaufman said.
It’s better to maintain a food safety program at all times, rather than springing into action when expecting a visit from an auditor, he said.
Inspectors from the U.S. Food and Drug Administration now have the authority to come onto farms to review food safety practices unannounced, he said.
“This is something that is definitely coming and will become a part of the culture of farming,” Kaufman said.