The following guidelines are based on the latest research based information from the produce industry as well as FDA’s guidance on food affected by hurricanes, flooding and power outages.

There are many environmental concerns following a flooding event. For produce growers, there are impacts to existing crops, potential water and soil contamination, and questions on how to remediate fields for future crops. Counties in WNC that were directly impacted with unprecedented flooding from Hurricane Helene, should approach any flooded waterways or fields with caution, as there is a high likelihood that flood waters were contaminated with microbial, chemical and physical contaminants.

Potential Contaminants

Microbial contamination can result from the disturbance of stream sediment that often contains accumulated pathogens, failing septic systems, mortalities, runoff from livestock operations or domesticated animals, and other forms of human waste.

Chemical contamination can occur from petroleum products, gas, pesticides, chemical spills and other undesirable chemicals or heavy metals that entered the water supply during flooding.

Physical contamination can include trees and vegetative debris, building materials, structures, vehicles and other large items.

Assessing Flood Impacts on Produce Fields

If your farm experienced flooding, you should conduct a field assessment to gauge the areas that have been affected. Our Extension team can assist you with the assessments to identify what resources are available, and what practices will need to be followed to address microbial or chemical contamination. It is important to determine what areas may have been flooded, and what areas experienced pooling of rainwater.

Flooding vs. Pooling

Flooding is when water outside of the control of the farm, and from unknown sources, accumulates in or around the areas where produce is grown. Floodwaters can be contaminated, which further contaminates the produce grown in the field. All produce that came in contact with flood waters is considered adulterated and must not be sold or given away for human consumption.

Pooling is when water accumulated around the crop that came only from rain or irrigation water. This water is considered safe and won’t contaminate the crop. If your farm was only affected by pooling from the excessive rainfall and not from outside sources of water from rivers, streams, or springs then that rainwater itself would have not brought contamination to your field. If you resume activities such as harvesting, packing and washing produce, it is important to make sure that the water you are using is not a possible source of contamination.

To better understand how these definitions affect fresh produce watch this video from the CA Leafy Greens Marketing Association (LGMA). Spanish version

There are 3 types of flooding:

1. Crops that have been in direct contact with flood water
2. Crops that have been in proximity to the flooded area but have not had direct contact with flood water
3. A field that was partially or completely flooded before a crop is planted

Any crop that has been in direct contact with flood waters is considered to be adulterated and should not be harvested, as it is unfit for human consumption. Neither is it recommended to harvest flooded crops for use as seed crops, since certain pathogens can persist in plant parts that were not directly touched by floodwaters.

Due to the possibility of lateral movement of water below the soil surface, a buffer of at least 30-feet should be identified between the flooded areas of the field and crops that were not impacted by the flood event. Assess your fields carefully, as simply walking from a flooded area of your fields to unaffected areas can transmit potential contaminants. Clean and sanitize any equipment that has been in contact with flooded soil. Based on FDA guidance, it is advised to wait a minimum of 30 – 60 days before replanting a flooded area with consumable crops.

Used with permission from the California Leafy Green Marketing Agreement (LGMA)

Remediation with Cover Crops

Planting cover crops on flooded soils is one measure of soil remediation, and will help stabilize bare soils during the fall and winter seasons. As we approach the end of our growing season, cool season cover crops are recommended.

Winter rye, winter wheat, daikon radishes, rapeseed, and other brassicas, oats, alfalfa, Austrian winter peas and hairy vetch are potential options. Though we are past our typically recommended sowing window, many of these crops can still germinate at cool temperatures, though expect the growth rate to be slower. These crops will help keep soil in place, slowly build back organic matter, and should not be consumed, but rather removed or incorporated into the soil in the spring. Specific guidance on how to terminate the cover crop prior to planting next season’s produce crops will be dependent on soil test results.

The N.C. Cooperative Extension, Buncombe County Center is sourcing a limited amount of cool season cover crop seed which will be available for farmers with flood damaged fields. Contact one of our Extension agents if you are in need of these cover crop donations.