From Cornell University:
To protect consumers from foodborne illness, produce farmers should wait
24 hours after a rain or irrigating their fields to harvest crops,
according to new research published in the journal Applied and
Rain or irrigation creates soil conditions that are more hospitable
to Listeria monocytogenes, which when ingested may cause the human
illness Listeriosis. Waiting to harvest crops reduces the risk of
exposure to the pathogen, which could land on fresh produce.
Cornell scientists, along with other agricultural researchers from
around the country, are conducting more food safety research in order to
set rules, standards and guidelines for the Food Safety Modernization
Act, which became law in 2011.
“We’re looking at the science that helps governmental entities, such
as the U.S. Food and Drug Administration, and private entities create
policies that keep our food supply safe,” said Daniel Weller, a doctoral
student in the field of food science and the lead author of the new
work, “Spatial and Temporal Factors Associated With an Increased
Prevalence of Listeria monocytogenes in New York State Spinach Fields.”
The other authors are Martin Wiedmann, Cornell’s Gellert Family
Professor in Food Safety, and Laura Strawn, assistant professor at
Factors such as proximity of a field location to water and other
landscape features also play important roles in the presence of
The researchers tested fields in a variety of locations
throughout New York and found that after rains or irrigation, the
chances of finding Listeria were 25 times greater. But, after the fields
dried at least 24 hours, the chances of detecting Listeria dropped
dramatically, to levels similar to baseline.
Currently, the U.S. Food and Drug Administration has proposed rules
allowing farmers to apply “wait periods” after application of irrigation
water. This would allow for “potentially dangerous microbes to die
off,” said the FDA.
Through a combination of weather data, GIS technology and data driven
information, technology allows farmers and producers to take a systems
approach managing food safety.
“Current technology tools are improving food safety and increasing consumer confidence in food products,” Wiedmann said.
The Center for Produce Safety funded this research.