Jan 11, 2016
Sanitation essential aspect of greenhouse production

Sanitation is the easiest way to prevent the spread of pathogens and insects, maintain a healthy crop and prevent foodborne illness in consumers of greenhouse vegetables, according to a Michigan State University Extension educator.

Greenhouse and Extension Educator Heidi Wollaeger outlined key elements of greenhouse sanitation practices at the recent Great Lakes Fruit, Vegetable and Farm Market EXPO, held in Grand Rapids, Michigan

“Greenhouse growers should start clean, and end clean,” she said.

Start by power washing empty greenhouses or replacing plastic covering. Using sanitizing agents between crops is a good practice. These could include ethanol, chlorine bleach, quaternary ammonium, hydrogen dioxide or chlorine dioxide.

Prevent overlap between crops susceptible to similar diseases, and do not hang ornamental hanging baskets over vegetable crops.

Remove weeds in the greenhouse, manually, Wollaeger said.

“We strongly recommend that you do not apply herbicides in the greenhouse as they can volatilize and damage crops months after application,” she said. “Marengo (OHP) is a pre-emergent herbicide labeled for greenhouse use.”

Clean irrigation equipment according to manufactures’ recommendations. Some growers fill the irrigation lines with sulfuric acid and rinse to dissolve buildup and sanitize.

“If you had an outbreak of any serious pathogen, like pythium, phytophthora, thielaviopsis or tobacco mosaic virus, during last growing season, be sure to replace all weed mats in affected areas,” she said.

Clean up leaf litter throughout the season and take out the trash: infected plant material should never be composted but instead placed in a plastic garbage bag and removed from the premises.

Wollaeger suggested the use of use footbaths, disinfectant mats and disposable plastic “booties.”

Requiring the use of lab coats, coveralls, or uniforms that should never leave the premises is wise. Also, require hairnets in packing areas.

It’s important to monitor vapor pressure deficit (VPD) and other environmental factors.

“Environments with very low VPD (aka high relative humidity) are conducive to disease,” she said.

Remove all dirt (on equipment, floors, pots, pipes) that can carry many pathogens including pythium, fusarium or phytophthora.

Wollaeger said it’s essential to implement security procedures: Monitor visitors entering and leaving the premises, follow check-in and check-out procedures for all employees and prevent workers of one area of the greenhouse from entering another area of the greenhouse.

Another aspect of enacting key greenhouse sanitation procedures is to learn about Good Agricultural Practices and Good Handling Practices.

“Know the microbial hazards in your water,” she said. “Install proper sanitation and environmental protection equipment. Encourage good worker hygiene and develop appropriate worker sick-time policies.”

Learn about proper handling/packing requirements for vegetables or herbs being grown, Wollaeger said.

Gary Pullano

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