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 Environmental Microbiology.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.