Spotlight: Starting the Season Clean

Empty greenhouses between crop cycles give growers an ideal opportunity to make a clean start for the coming season. Good sanitation practices now will help get crops off to a healthy start, and will encourage good sanitation behaviors throughout the season. Cleaning greenhouse walls and ceilings will increase the amount of light reaching your crop. And for growers who retail their crop in the same greenhouses where they grow, good sanitation gives customers a positive impression of the business and the quality of the plant products.

In the Greenhouse and Nursery

Sanitation begins with cleaning up crop debris and potting media from previous crops. Decaying plant tissue is a source of plant pathogens and it should be removed from the greenhouse completely. Old potting media can also harbor pathogens and weed seeds, and can be a place for insects to develop, such as thrips pupae and fungus gnat larvae. Weeds must be controlled within greenhouses and nursery overwintering houses. The weeds can serve as a reservoir for pathogens and provide harborage for insects. Weed seeds can also be spread into your crop, increasing your labor expense and decreasing profits. If you do not have concrete floors, commercial weed block fabrics are one effective method for reducing weeds in greenhouses and are easy to install in empty greenhouse. Herbicides are another method for weed control in greenhouses, but there are a limited number of herbicides that are labeled for greenhouse and overwintering house use. Find more information on which herbicides can be used in your greenhouse.

Algae are also common in greenhouses on floors, walls and cooling pads. Algae can make walkways slippery and hazardous to employees and customers, and provide food and breeding sites for shoreflies. Algae problems can be resolved sometimes by improving drainage, removing crop debris, and allowing surfaces to dry. When those actions do not resolve an algae problem, one of the sanitation products listed in Table 1 may be needed.

Clean and Sanitize

There are a variety of sanitation products available for green industry use. A list of the most common chemical groups of sanitation products is listed in Table 1. Before using these products you must physically remove all waste and debris because organic matter inactivates some of the sanitizing chemicals or they may simply inhibit the ability of the product to physically contact the surface. Read the product label carefully and be sure to use the product for the amount of time listed on the product label. Not keeping a surface or a tool wet with the sanitizing product long enough will cause the treatment to be ineffective. The treatment time needed varies from product to product and from surface to surface.

There are also many commercial cleaners that are made for greenhouses, evaporative cooling systems, greenhouse glass and plastics, and irrigation systems. These include Floralife Strip-It® Cleaner, Pace Strip-It (active ingredients sulfuric acid & ammonium bifluoride) which can be used on greenhouse structures and irrigation systems to remove whitewashes, organic sludge, oil, dirt, grease, calcium and hard water deposits. The products are for end of season clean-up use only. Other Irrigation line cleaners include Line Blaster® and Line Blaster Organic® (active ingredient Dioxidane ). Line Blaster Organic® OMNI listed. These will also help clean out irrigation line buildup. Contact your local extension educator or the author for help with understanding your option for cleaning products for specific situations.

Develop a Sanitation Protocol

As a production manager, you may be well aware of sources of plant contamination, but often your seasonal help is not. A Sanitation Protocol is a written plan that clearly communicates to all employees your expectations for keeping your business clean. A formal plan emphasizes the importance of each employee’s roles in keeping plants healthy and will encourage consistent performance of best management practices for sanitation. Ideally a sanitation protocol will be customized to address sanitation concerns of your individual business and might include detailed instructions such as:

• All employees will use a boot wash before entering propagation areas in the greenhouses. The boot wash solution will be refreshed daily.
• All employees will wash hands with soap and water before handling cuttings and plugs.
• Employees will not cull diseased plants nor groom plants during watering. Plants culling will be done as a specific task and hands will be washed following culling.
• Plant waste will be removed from the greenhouse daily. Plant waste cull buckets will not be stored in the greenhouse and will not be left in front of ventilation fans.
• Employees will not bring food or drinks into production areas.
• Samples of plants with disease will be sent to a pathology lab for diagnosis.
• Hoses ends will be secured in a position elevated from floor surfaces to avoid contamination.
• Watering wands and nozzles will be cleaned between uses and allowed to air dry. They will not be placed on floors.
• When receiving plant shipments, the new plants will be placed in a quarantine area so that they can be scouted for insects and disease before mixing them in with the existing plant stock.
• “Pet” Plants from home will not be stored in the greenhouse over winter.
• All pots, benches and floors will be sanitized between crop cycles. Tools and equipment will be sanitized following each use.

Good sanitation can help reduce insect, disease and weed problems, reduce pesticide and labor expenses and improve your company image. But good sanitation practices take time and planning to execute. So don’t wait until the day before you move your crops into your greenhouses - initiate your good sanitation practices now.

More New Year Tasks

Greenhouse and Nursery Growers: now is a perfect time to take a water sample. Well water pH and EC does change overtime. A water sample now will help you to determine if your water quality has changed in the last year and will help you determine the best fertility program for your crops this spring. It is also ideal to test your new potting substrates as well.

• Inventory the pesticides and additives that you have in your storage room.
• Make sure that all are labeled.
  
• Make sure you have a MSDS for each chemical that you have and keep them in an easy-to-find location.
  
• Make a list of old chemicals or pesticides that you will not be using and plan to have the Pennsylvania CHEMSWEEP Program take the chemicals off your hands for free. CHEMSWEEP is offered in different counties each year. In 2012 it will be offered in Armstrong, Bucks, Cambria, Centre, Chester, Clarion, Dauphin, Forest, Fulton, Indiana, Lancaster, Lebanon, Lycoming, Mifflin, Philadelphia, Susquehanna, Tioga, Venango, Wayne and Wyoming counties.
  
• Get more information on CHEMSWEEP Waste Pesticide Disposal Program. 
• Inventory your personal protective equipment (PPE). Dispose of old or damaged PPE and order new PPE for the coming season. Refer to your pesticide labels to determine which PPE you will need in 2012.
• Order new parts: Greenhouse ventilation fan belts get worn, and sprayer nozzles get worn or clogged. Repair equipment and replace worn parts now, so that you will be ready for business when the weather breaks. Remember that PPE should be worn when cleaning and repairing machinery used for pesticide applications.

Table 1

A Sample of Greenhouse Sanitizers, Disinfectants and Cleaners*. This list does not represent all products available. Actual use sites and instructions may vary according to product, always read the label to make sure that the product you are using is appropriate for your situation.

*Remember that greenhouse disinfectants are pesticides and you must follow the label as you would with all pesticides. Make certain to wear the proper PPE.

Article Contact

Ruth Benner, Penn State Extension