COLUMBUS, Ohio — Consumers and farmers have the perception that greenhouse production is safer than field agriculture because it has no exposure to the outside environment. Sanja Ilic, state food safety specialist for The Ohio State University, thinks the risk is not lower – just different.

 

Ilic, her colleague Melanie Lewis Ivey, an OSU plant pathologist, and other researchers are analyzing findings from an on-site survey of 26 greenhouses they did across the United States.

The production in greenhouses is intense, with pooling water, higher humidity and higher temperatures – conditions conducive to the growth of microorganisms, Ilic said. It is important for growers to be aware that there is a food safety risk in the greenhouse environment and that they have to have a food safety plan in place.

“Most importantly, the food safety plan has to consist of a workers’ health and hygiene plan,” she said. “We have observed that in 78 percent of the greenhouses when they are harvesting their greenhouse vegetables, the greenhouse workers don’t wash their hands.”

The researchers also noticed the majority of greenhouses don’t sanitize the surfaces, direct-contact spaces such as scales and containers and indirect contact surfaces such as flooring, gutters and walls.

Also, a greenhouse crop can often be grown perpetually. Sometimes growers don’t have a cleanup period between two crops but would interplant, Ilic explained.

They pull out the old crops and keep growing the new one. There is no break between the two growing seasons, so the surfaces are not sanitized.

Ilic emphasized she is not critical of the farmers’ practices, but that the researchers rely on the farmers to tell them what problems they have and then they focus on practices. They want to come up with a scientific solution that has something to do with practices.

“We work with our greenhouse growers and farmers to come up with solutions

together,” Ilic said.

One grower Ilic worked with is Matthew Kispert, horticulturist at CropKing, Inc. in Lodi, Ohio. CropKing is a manufacturer and supplier of greenhouses and hydroponic growing equipment. The company also has a greenhouse operation.

“Hydroponic systems are unique in that; with the NFT gutter system (a system recommended for commercial growers by CropKing), the water is recirculated through for a period of two to four weeks, and then we do a water change,” Kispert explained.

If a contamination event were to happen in that water, no research has been done to see how fast it would spread.

Greenhouse growers don’t know if the contamination will die off or proliferate, he said. That could be an area of concern which would require additional types of sanitation. “One thing they’re going to look at is if the pathogens are in the water, can they travel up the plant to the harvestable portion?” Kispert added.

He is developing a food safety plan, he said. The most important thing in such a plan is cultural controls, convincing the employees it is important to maintain proper sanitation and not to cause cross-contamination.