West Lafayette, Ind., Jun. 17 - Vegetable and fruit crops partly or completely submerged in floodwater or that might have come in contact with the water could be contaminated with microorganisms and should not be sold or consumed as fresh produce, said Purdue University Extension specialists.
Inedible flowers and other floriculture crops with flood residue should be cleaned and disinfected before they are sold, the experts said.
Depending on the growth stage of vegetable crops, producers are prohibited by the U.S. Food and Drug Administration from marketing those crops, said Elizabeth Maynard, Extension vegetable crops specialist. In any case, there is a high health risk from consuming produce submerged in or splashed with floodwater, she said.
"For edible crops, there is the risk that the crops have been contaminated with pathogens or chemicals," Maynard said. "These crops should not be harvested for sale as fresh produce. This may come as very unwelcome and unexpected news for producers."
Indiana produced about $136 million worth of vegetables and fruits in 2006 and ranked among the top 10 states in the production of tomatoes for processing, cantaloupes, watermelons, snap beans for processing, cucumbers for pickles, and blueberries in 2007, according to the Purdue-based Indiana Agricultural Statistics Service (IASS). The production value of Indiana's vegetable and fruit crops was more than $111.5 million in 2006, the IASS reported.
Producers won't be able to salvage flood-damaged vegetables and fruits for fresh consumption because if crops have experienced surface contamination it is possible microorganisms have moved into plant tissues, Maynard said.
"There are no sprays that would be appropriate for either the soil or the crop to reduce the risk of contamination," she said. "Any sanitizer would become ineffective based on the level of organic material present in the soil. Washing does not eliminate pathogens, so we're recommending producers focus on reducing the risk by discarding affected crops or incorporating the crops into the soil."
The risk level for suspected flood-tainted fresh produce crops varies according to the crop development phase, Maynard said. Maynard and colleague Shari Plimpton of the Center for Innovative Food Technology, a division of EISC Inc., described those phases and risks as follows:
* Edible portion of vegetables or fruit present - very high risk. The crop is considered adulterated by the FDA and cannot be sold for consumption.
* Crop has emerged but edible portion is not present - high risk. The potential presence of microorganisms in the plant, as well as in the soil, could result in indirect contamination of the crop after floodwaters recede.
* Crop has been planted but has not emerged - high risk, for the same reasons as emerged crops.
* Crop has not been planted - moderate risk. Soil contamination could be as high as if it had been treated with noncomposted manure. To reduce risk, planting should not be done for at least 120 days after floodwaters recede.
Fruit growers should not assume their crops are safe from contamination even if the fruit grows on trees, said Peter Hirst, Purdue Extension commercial tree fruit specialist.
"It might be safer not to sell or eat any fruit from flooded orchards, whether or not the fruit has been in contact with floodwaters," Hirst said.
For flowers and ornamental plants that have been in floodwater, growers can use horticulture-approved wetting agents or surfactants at low rates to help remove residue, said Roberto Lopez, Purdue Extension commercial floriculture specialist.
"This may take off some, but not all, of the residue," Lopez said. "Plants should be treated on a plant-by-plant basis and tested for phytotoxicity. It is important to remember that no studies have been conducted to see if wetting agents or surfactants are effective for this purpose."
An alternative cleaning method involves using insecticidal soaps that are labeled for use on plants, said Janna Beckerman, Purdue Extension plant pathologist.
"Treat plants with the soap and then allow them to sit for a few minutes to dissolve the residue," Beckerman said. "Then rinse with water from a separate sprayer. Because it is labor intensive, this method might only be feasible for high-value plants."
Indiana greenhouse growers produced more than $60 million worth of plants in 2005.