ONTARIO, Ore. — Oregon State University researchers here are looking at ways to help onion growers follow possible federal rules that would limit how much bacteria can be present in irrigation water.
The U.S. Food and Drug Administration has proposed a produce safety rule that would limit how much generic E. coli bacteria can be present in irrigation water, require farmers to test their water weekly and stop using it if it exceeds a minimum threshold.
Onion growers say the rules aren’t necessary or scientifically sound and would be costly, with no public safety benefit.
The FDA will release a revised rule before the end of the summer and onion growers are hopeful it will include substantial changes to the part of the rule dealing with allowable bacteria levels in irrigation water.
But OSU researchers are proceeding with their experiments so growers aren’t caught flat-footed if the irrigation water rule isn’t significantly altered.
“There wasn’t any sense delaying the research to wait and see what is going to come out,” OSU cropping systems extension agent Stuart Reitz said. “We want to make sure … we have the information necessary to ensure we can keep growing onions in the valley.”
Reitz and other OSU researchers are looking at three main ways growers could meet the proposed FDA standard for allowable E. coli levels in irrigation water.
One method would involve applying a copper fungicide over the top of onions and researchers are comparing bacteria levels in treated plots vs. untreated plots.
Another possible solution could involve treating ditch water with a copper sulfate compound. Bacteria counts are being measured before and after treatments.
A third possibility is injecting chlorine dioxide through drip irrigation tape to kill off bacteria. Growers already use chlorine to keep drip lines clear of algae.
Reitz said researchers are trying to determine rates that are “low enough to kill off bacteria and economically viable for growers to use.”
He said all those products are already registered for use in onions.
“In Stuart’s research, he’s dealing with products that are already registered on onions,” said Nyssa farmer Reid Saito. “To prove, or disprove, that these products work … would really help us deal with any potential new food safety rules and regulations.”
OSU researchers provided growers and industry representatives an update Aug. 26 on their continuing research on whether E. coli bacteria in irrigation water poses a threat to onions.
This is the second year of the field trials and Clint Shock, director of OSU’s Malheur County experiment station, said they’re important whether or not the FDA revises its proposed rule.
“It’s really important that we have safe produce and our growers are assured they are delivering safe products to the marketplace,” he said.
So far, Shock said, the trials have shown that E. coli contamination is not a risk in furrow- or drip-irrigated bulb onions, regardless of water quality.