Four Food Safety And Handling Considerations For Greenhouse Vegetables

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Vegetable production isn’t all that different from ornamentals production for a veteran grower. But if you’re growing vegetables to harvest and market rather than selling the plants themselves, there are some important differences. As an edible crop, there are some food safety and handling considerations you may not have thought about.
 
Before you decide to add produce as a new greenhouse crop for your operation, be sure to consider the following issues:

1. Water quality and testing. It may be necessary to make a complete water analysis when growing vegetables in the greenhouse. Testing irrigation water for pathogens and keeping water test records are good agriculture practices and an important part of on-farm food safety planning. Most laboratories will test for E. coli and other possible pathogens. For instance, a greenhouse facility using pond water or an artesian well should do a water analysis more frequently during warmer months in order to prevent problems with pathogens.

2. Temperature and storage. Most facilities growing and harvesting greenhouse produce have a separate packing area where the temperature can be closely controlled. Temperature in the packing area usually falls somewhere between the temperature measured in the greenhouse and the temperature kept in the cooler.  Those areas should be kept cleaner than the growing area.  

Tomatoes are very sensitive to mishandling and improper storage conditions. Because they can be injured by either low or high temperatures, proper postharvest handling and storage methods are essential for maintaining acceptable quality and promoting long shelf life. Tomatoes are also subject to a large number of postharvest diseases. Some of the more common are alternaria rot (Alternaria alternata), gray mold or botrytis (Botrytis cinerea), rhizopus rot (Rhizopus stolonifer) and sour rot (geotrichum candidum). Although the skin of vegetable fruit offers some protection against infection, it is easily damaged by rough handling. Pathogens can enter through a variety of openings. A temperature of 58° F to 60° F is best for slowing the ripening of mature green tomatoes and preventing existing decay.

3. Chemicals and preharvest interval. Depending on your location, some pesticides are allowed and some are not, so you need to verify the materials you plan to use with your state agriculture department.

It is also important for the grower to know and keep good records of where he has sprayed chemicals in his greenhouse. Those areas should be restricted areas. Because these are food crops, most pesticides will have a specified preharvest interval between the last application and harvest. Only when that time interval has passed is picking possible in those areas.

4. Employee training for proper handling procedures. Vegetables are soft fruits. Employees must pay special attention when picking the fruit. The fruit must be placed in boxes, not thrown. Vegetables need to be harvested at the mature stage: for example, not too red and not green with tomatoes. Ripening charts are available and useful during training of employees. Some customers may require you to cut the tail off tomato fruits. The tail can puncture other tomatoes and cause damage that leads to disease development.

A packing crew needs strong training in both handling and quality control. It is a key point for your operation. Those employees will decide what fruit is graded top-quality, secondary quality or culled as garbage. They are the ones who will help you develop a reputation for quality produce.

Régis Larouche (r.larouche@agrisys.ca) is an agronomist with Agrisys Consultants Inc. His specialties include crop protection, biological control and computerized climate control of the greenhouse environment.
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