WEST LAFAYETTE, Ind. — 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.

For more information on general flood recovery information, visit the Purdue Disaster and Emergency Management Resources page at http://www.extension.purdue.edu/eden/disastertopics/
floodstorms/index.html .

In addition, the U.S. Department of Agriculture Risk Management Agency has partnered with Mid American Ag and Hort Services Inc. on a fresh produce food safety initiative. To learn more, call (419) 724-2930 or visit http://www.midamservices.org .

WEST LAFAYETTE, Ind. — Hoosiers should keep their umbrellas and flashlights handy because the thunderstorms that have marked spring, especially early June, likely will continue until the end of July.

Infrared satellite images of southern Indiana show widespread flooding of the White and Wabash rivers. The image on the left was taken on May 28, before the record rainfall, and the image on the right was taken on June 10. The images have a resolution of approximately 275 yards (250 meters). Purdue University’s Terrestrial Observatory captured the images from NASA’s MODIS-Aqua satellite.

La Niña’s control of the weather pattern will continue to make Indiana’s normally severe storm season more intense and generate storms more frequently than average, said Dev Niyogi, state climatologist and an assistant professor of agronomy and earth and atmospheric sciences at Purdue University. La Niña is a name given to the interaction of the atmosphere with cooler than normal sea surface temperatures in the tropical Pacific. This impacts global weather patterns.

“Whenever we are in a La Niña pattern, there is increased propensity for severe weather over Indiana during spring and summer with increased likelihood for thunderstorms and rain,” Niyogi said. “We are nearing the end of the La Niña cycle, which started last year, but the sea surface temperatures are still about one-half a degree cooler than normal.”

The cool ocean surface temperature and recent precipitation deluge tell climatologists that La Niña still has some punches to throw, he said.

La Niña could be the major reason for the weather pattern responsible for 9.85 inches of rain in Gosport in Morgan County on June 7. Edinburgh, Ind., has the rainfall record for the week of June 2-8 with 17.94 inches and also for a single day with 9.95 inches on June 8. According to the National Weather Service, precipitation of this magnitude is considered a 1-in-1,000 year event.

Although the current La Niña is coming to an end, Niyogi said that it’s likely the weather will continue to be wet all summer. But it’s difficult to predict amounts of rain or exactly where it will fall, he said.

“Rainfall is one of the most complex factors in nature,” Niyogi said. “The ground temperature, whether the ground is too wet or too dry, the altitude, the air temperature and humidity all interact to determine where precipitation will fall.”

Many of those factors came together over the southern third of the state during the first two weeks of June, he said. The effect was that a weather pattern of thunderstorms with heavy rain formed over that large area of Indiana and caused flooding. So much rain on already saturated ground, left water with nowhere to go except into homes, businesses and fields that quickly took on the appearance of new swimming pools and lakes.

“It’s difficult to say why some areas were hit with widespread heavy precipitation,” he said. “We’re still studying why some places receive heavy precipitation and others don’t. But we do know that people in Indiana should be prepared for more flooding.”

WEST LAFAYETTE, Ind. — Every toilet flush and running faucet can place an additional burden on septic systems in homes ravaged by Indiana’s floods, said a Purdue University Extension agricultural engineer.

Older septic tanks or those in poor condition might be vulnerable to flooding, which can cause wastewater to back up into the house and possibly even lead to permanent septic system damage, said Don Jones.

Jones advised homeowners with flooded septic systems to limit their water use until floodwaters recede and soils have had an opportunity to dry.

About 800,000 homes in Indiana have private sewage systems.

“A high water table – the kind you would see in a flood – can become a problem if there are cracks in the septic tank or the seals around the tank aren’t very good,” Jones said. “This is probably a bigger concern for septic systems that are at least 10 years old.”

Septic systems in Indiana use soil absorption fields to treat and disperse the wastewater that leaves the septic tank. In normal conditions, the systems remove nitrogen and pathogens from the wastewater before the pathogens reach groundwater. In flood conditions, however, saturated soils can prevent proper wastewater treatment and dispersion from taking place, resulting in sewage backups and potential groundwater contamination.

“You could even get water running back into a newer, watertight septic tank if there is not much slope in the soil field,” Jones said.

Septic tanks not equipped with effluent filters could face long-term damage to the filter field, Jones said. Many older tanks are not fitted with the filters.

“The filter is used to prevent solids from being washed out of the tank, even when the liquid level in the pump is high,” he said. “This keeps solids and scum in the tank from reaching the filter field, even when the filter cartridge is removed for cleaning.

“If no filter is present when the wastewater level in the tank is above the outlet baffle, some of the floating solids and scum can overflow into the soil absorption field as it dries out. If water from the soil field is able to back up into the tank, is stirred up and then runs out again, even more solids could end up in the soil field. This can affect the system in the near term and even shorten the life of the soil field.”

Homeowners with submerged septic tanks should have the systems inspected once floodwaters abate, Jones said. He also recommended homeowners:

• Avoid removing the septic tank lid while the tank is still under water. “In addition to flooding the system, someone could even fall into the tank,” Jones said. “It’s good to just leave it alone until the water goes away.”
• Minimize water use until soils are no longer soggy. “The soil doesn’t need any more water,” Jones said. “If you need to do laundry, go to a coin-operated laundry. Keep water use in the home to a minimum, even if the water is still flowing out of the house into the septic system.”
• Shut off power to septic system sewage pumps until floodwater goes down.
• Remove all silt and other material from the septic tank, distribution boxes and sewage pump chambers after water recedes. This requires a professional.

Above all, be patient and allow the soil a chance to dry, Jones said.

“With the water table as high as it is in some parts of southern Indiana right now, that’s going to take a few days, or even weeks,” he said.

For additional information and tips on septic systems and flooding, read Purdue Extension publication HENV-10-W, “Septic Systems in Flooded and Wet Soil Conditions,” by Jones and Purdue agronomist Brad Lee. The publication is available online at http://www.ces.purdue.edu/extmedia/HENV/HENV-10-W.pdf or by calling Purdue’s toll-free Extension hotline at 1-888-EXT-INFO (398-4636).