Residue Management Benefits a Clear Advantage

After numerous food-borne illness outbreaks in recent years, food safety has moved to top of mind for consumers. Currently, there are a number of bills in the U.S. Congress to impose more stringent rules on food safety practices and tracking. While recent outbreaks have been spread by pathogens like Salmonella and e-coli, consumers also are concerned about residues of chemicals that may be present on fresh produce.

According to Mark Ritenour, Ph.D postharvest physiology and handling with the University of Florida, there is always a movement afoot globally with changes to the maximum residue limits (MRLs) for chemicals that are allowed on food items. The U.S. and other countries set MRLs on fresh produce for various chemicals. U.S. MRLs are rarely exceeded when the label instructions for pesticides are followed. However, when MRLs set by importing countries are lower than U.S. MRLs, then use of these pesticides usually must be discontinued or modified to keep from exceeding the country’s tolerances. The European Union (EU), in particular, has drastically lowered MRLs for many important pesticides in recent years.

Attention to MRLs will only grow in importance in the coming years as countries try to harmonize residue limits and some use residues as a trade weapon to block competing nations’ fresh produce from entering its markets.

Ritenour points to an example where U.S. MRLs and the EU’s conflicted with a citrus shipment from Florida a couple of years ago. The residue limit for carbaryl for the U.S. and most major export markets is around 10 parts per million (ppm) (ranging from 7 to 15 ppm), while the EU’s limit is 0.05 ppm. The fruit was shipped to the EU six months after the carbaryl application, but still tested for 0.08 ppm for residue, which is still extremely low. This level is fine by U.S. and most export market standards, but not the EU’s.

“If U.S. produce is shipped to a country and exceeds its MRLs, it will be rejected,” says Ritenour. “That means it will be destroyed or will have to find an alternative market. Either way, it will be very costly for the grower and shipper.”

Peace Of Mind

Produce growers concerned about residue levels, especially those growing for the export market, should consider the use of Bt products for worm control. Why? Bt products are exempt from residue limits, because they are designed to very specifically target certain pests and are safe to humans.

In addition to no residue worries, Bt products should be considered as an important part of produce growers’ pest control management strategies. They provide effective worm control and make for a good chemistry rotation partner in an integrated pest management approach.