MSU Extension Agrifood Safety

Rodents and birds pose a significant contamination risk to produce after it is picked. Feces from rats and birds can spread E. coli and Salmonella on produce and packaging. Minimizing and controlling rodents should be a part of farms where produce is packed or stored in close proximity to the production area.

This guidance document addresses due diligence for rodent and vertebrate pest control and offers a standard operating procedure (SOP) boilerplate that can be adapted to your farm and help address rodents and other vertebrates in storage and packing areas.

There are three steps to dealing effectively with rodents and other vertebrate pests with respect to Good Agricultural Practices. These steps are determining the risk and mitigation tactics you will use, enacting the changes on the farm and documenting that you are carrying out the changes.

In assessing risk, you want to consider the areas your crop resides in from the time it is harvested until it leaves your farm. Think about storage areas and pack houses. Are these areas prone to rodents or birds getting into them? Are there roosting spots for birds over the areas you keep filled wagons prior to shipping them? What could you do to help minimize contamination by these pests?

The best way to manage vertebrate pests is to use multiple tactics to minimize the impact of them. Try to reduce the suitability of habitat around your farm by reducing rubbish piles and high grasses. Store produce in shady structures equipped with netting in the rafters to exclude bird roosting. Use bird repellants like the distress calls of birds, Avitrol* or noise cannons to deter roosting. Place a series of rodent traps around the packing area and monitor them daily to check for caught rodents. Every tactic you use should be documented in your SOP. The sample policy below can serve as a general guideline.

Rodent and Vertebrate Pest Control SOP

Presence of rodents and other vertebrate pests can cause contamination of produce with human pathogens through direct contact or presence of fecal matter. Efforts are made to keep rodents, wild and domestic animals out of packing and produce storage areas. Birds will be discouraged from entering storage areas (specify means such as, by use of plastic strips across doorways and/or netting across rafters). Potential food sources will be eliminated, aside from crop, that may attract vertebrate pests. Weeds and debris that may act as food source or habitat for vertebrate pests will be removed adjacent to the packing area and the field itself.  

An effective rodent control strategy must include trapping. For the purposes of Good Agricultural Practices, it is important to include a map of where the traps are located around the packing and storage areas in your GAP plan. In addition, you will want to keep a log of when you check these traps. Specify in the GAP Manual that this is being done. Sample language about controlling rodents can be found below.

Traps will be set and monitored regularly to assess and eliminate risk of rodent contamination. A trap placement map and completed monitoring forms are included in the GAP Manual.

When choosing traps, always opt for those traps that actually kill the rodent in the trap and avoid poison bait traps. Dying rodents can pose a food safety risk if they crawl off into a produce container to die.

Many growers number their traps for ease of monitoring. To make the traps conspicuous, they often mark the areas above the locations of the traps with a label listing that a rodent trap is there and what number it is.

Included in this episode’s show notes are copies of a generic rodent trap monitoring form. As always, SOPs and documents must be customized for the type and scale of operation. In cases where an operation does not have a pack house or produce storage area, there may be no need for a rodent and vertebrate pest control SOP.

It is helpful to remember, the auditor is looking for evidence of a system written in the GAP Manual to minimize incidence of foodborne illness, visual evidence that it is taking place and documentation that it has been taking place in the past. Writing the vertebrate control SOP is the first step. Implementing the practices on your farm is the next step. Documenting that you check the rodent traps is the final step.