Hurricane Helene has seriously compromised the different water sources that can be used for crop management foliar applications. Due to the timing of the storm there are some crops that are yet to be harvested and farms will need to continue with their pesticide programs before the crop is harvested. Fungicides and insecticides are mixed with water and touch the edible portion of the crop. It is critical to ensure that the water used is not a source of contamination for the crop that will soon be harvested. Several studies have shown that some foodborne pathogens, especially Salmonella, will grow in some pesticide formulations once diluted to use-rates. Extension research has confirmed this on crops such as tomato and tree fruit in field environments and Salmonella actually survives better in combination with several fungicides than with the surface water alone, applied to foliar surfaces. 

Current challenges with water sources

 Municipal or city water: Boiling water advisories have been issued in many areas affected by Hurricane Helene due to concerns with contamination after municipal or private extraction treatment or contamination of the delivery systems. It is impractical to boil water that is used for spray applications. We expect these challenges to continue in the coming weeks. Even in areas where the notices are lifted, ongoing repairs to water treatment plants and wastewater systems may result in additional boiling water notices.

Groundwater (Wells): It is important to assess the condition of wells that will be used to spray crops that will soon be harvested. If a well has cracks, a loose cap, has been submerged by flood waters, or is near septic systems it is important to test the well. Air vents on wells are a direct route to the bore hole and, if submerged, may result in persistent contamination. A typical 100ml grab sample water test has been shown in recent studies to be inadequate to assess the quality of the groundwater to be extracted by a well. Minimally, it is recommended to have 1L of water tested by a qualified lab.The Health Department in Henderson County recommends that If you live near animal feeding operations, agricultural fields where pesticides are applied or industrial chemical factories, you should contact the health department for additional well water testing, especially if you smell fuel or chemicals in your water.

It is critical to inspect, purge and disinfect wells before use. For guidance on what to do before using a well after the storm, check this resource from NC State University. Chemical options to shock a well include the use of chlorine or peroxyacetic acid (PAA). SaniDate 12.0 whose active ingredient is peroxyacetic acid and hydrogen peroxide can be used to shock a well.

SaniDate 12.0 (EPA Reg. No. 70299-18) can be used to shock wells. Instructions for shocking wells using this product are listed below and can be found on page 3 on the product label. 

SHOCK TREATMENT FOR IRRIGATION WELLS
Use SaniDate 12.0 to limit survival and control bacterial growth in irrigation wells. To shock well water apply 0.56-1.13 gallons (72-145 fl. oz.) of Sanidate 12.0 per 100 cubic feet of well water to be treated; equivalent to a dilution rate of 1:1,335-1:665 (100-200 ppm of peroxyacetic acid). Surge irrigation well to circulate and allow a contact time of 48-72 hrs. If necessary, purge the well to remove any organic deposits. Pump the well until the water is clear. Test strips can be used to ensure peroxyacetic acid concentration is < 50 ppm in the water before using the water for irrigation on established plants.

Surface water (from farm ponds, creeks, rivers, reservoirs, lakes): WE DO NOT RECOMMEND, at the moment, to use surface water due to the high chance that the water is contaminated with microbial, chemical and physical contaminants especially in the counties that were directly affected with unprecedented flooding. Microbial contamination can come from scouring of water body sediments where pathogens accumulate, failing septic systems, mortalities, runoff from livestock operations or hobby farms with diverse domesticated animals  and human waste among other sources. Chemical contamination can come from petroleum products, gas, pesticides, chemical spills and other undesirable chemicals or heavy metals that entered the water supply during the storm and subsequent floods. Even if this water is treated with the products mentioned below there is no way to eliminate any chemical contaminants other than by extensive dilution with clean source water replenishment over time. .

Water Treatment for Spray Applications

One of the few products that is labeled to treat water used for pesticide spray solutions is OxiDate 5.0. This product is a broad-spectrum bactericide/fungicide. This product has a compatibility guide for mixing with different chemistries and has a pre harvest interval (PHI) = Zero (0) days. To access the full label for OxiDate 5.0 (EPA REGISTRATION NO. 70299-28) follow this link and see instructions on page 12. To access the tank mix and product compatibility guide click on this link.

 There are two similar products that are also labeled for water treatment of pesticide spray solutions. These products are OxiDate 2.0 and SaniDate 12.0. However, when we reached out to the Manufacturer of both products (BioSafe Systems), the company shared that currently there is not a compatibility guide for mixing the different chemistries present in different pesticides for OxiDate 2.0 and SaniDate 12.0. Due to this, we recommend growers use OxiDate 5.0 that way they have all the information needed based on the chemistry of the products being applied. 

 The following is extracted from the OxiDate 5.0 Label (EPA REGISTRATION NO. 70299-28) and should be followed when using this product for treatment of water used for pesticide spray solutions.

WATER TREATMENT

Treatment of Water Used for Pesticide Spray Solutions
Use OxiDate 5.0 as a bactericide/microbiocide to treat and suppress algae, bacteria and fungi in water collected from open or closed sources including but not limited to wells, ditches, canals, reservoirs, and ponds, used for pesticide spray solutions and mixtures. Add OxiDate 5.0 at a dilution rate of 1:700-1:2,500 (18.3-5.1 fl. oz. per 100 gallons of water) to water in a spray or mix tank. Mix and allow a contact time of 3-5 minutes before adding other pesticides to the spray solution.

Tank Mixing Instructions
1.Before adding other pesticides to the spray solution: Mix OxiDate 5.0 first and allow a contact time of 3-5 minutes.

2.When used with Conventional Bactericides/Fungicides/Insecticides/Miticides: Use OxiDate 5.0 at a dilution rate of 1:2,500 to 1:1,250 (5.1-10.2 fl. oz. per 100 gallons of water, equivalent to approximately 22-44 ppm of peroxyacetic acid). This rate range can be used with pesticides with or without metal ion(s).

3.When used with Organic (Biorational/Botanical/Biological) Bactericides/Fungicides/Insecticides: Use OxiDate 5.0 at a dilution rate of 1:2,500 (5.1 fl. oz. per 100 gallons of water, equivalent to approximately 22 ppm of peroxyacetic acid). The spray tank water treatment can be used on biorational/botanical based bactericides/fungicides/ insecticides/miticides (Ex. neem oil, sulfur, plant extracts etc.), Bacillus based biofungicides (spore containing or spent fermented media), Bt based bioinsecticides, copper based bactericides/fungicides Do not use OxiDate 5.0 with Mycoinsecticides (Beauveria, Metarhizium, Isaria based) or with other biological active ingredients not listed above.

4.When used with Micro-Foliar Fertilizers: Use OxiDate 5.0 at a dilution rate of 1:2,500 (5.1 fl. oz. per 100 gallons of water, equivalent to approximately 22 ppm of peroxyacetic acid).

PERSONAL PROTECTIVE EQUIPMENT (PPE)
Handlers who may be exposed to the undiluted product through mixing, loading, application, or other tasks must wear: coveralls over long-sleeved shirts and long pants, rubber gloves, chemical resistant footwear plus socks, and protective eyewear (goggles or face shield). Handlers who may be exposed to the dilute through application or other tasks must wear: long-sleeved shirt and long pants, and shoes plus socks. Follow manufacturer’s instructions for cleaning and maintaining PPE. Discard clothing and other absorbent materials that have been drenched or heavily contaminated with this product. Do not reuse them. If there are no such instructions for washables, use detergent and hot water. Keep and wash PPE separately from other laundry. 

Notes on the use of these products

1. Both of these products mentioned in this factsheet are registered pesticides with an EPA registration number. The instructions on the label must be followed. The Label is the Law! 
2. It is critical to use the PPE listed on the label. The active ingredient in both products is highly concentrated hydrogen peroxide and peroxyacetic acid. These ingredients are concentrated acids that need to be handled with care. Do not attempt to handle and mix these products without chemical resistant gloves and eye protection. 
3. The manufacturer recommends the use of test strips to verify that the target concentration has been reached for the treatment before adding the pesticide. Follow the directions on the test strip bottle carefully. 
4. Written records of the use of these products must be kept to show that the water was treated and that the concentration was verified with the use of test strips or a titration kit. This information should be kept for compliance with FSMA’s Produce Safety Rule and food safety plan (if the farm follows one). 
5. Please note BioSafe’s products (Sanidate 15.0, Sanidate 12.0, OxiDate 5.0) cannot be used for treatment of any type of drinking water used for human consumption. Please refer to the Label for rates and applications. 

Record keeping

It is important to record all water treatment that is conducted and keep it on file. Both the Produce Safety Rule and food safety audits allow written and electronic records. Below is a sample record form you can print or use on your computer to help keep track of treatment.

Water treatment record form for spray applications

Sample form to record water treatment of spray water

*The use of test strips is recommended to verify the concentration of the product.

Product availability in Western NC

We have reached out to BioSafe Systems to discuss the need to make these products and test strips available through their different pesticide dealers in Western NC. BioSafe products are carried by Helena, Nutrien, Coastal Ag, Ag Care and Southern Ag. 

Have additional questions

If you are a grower in Western NC or the Piedmont and have questions or need further assistance, please contact your local Extension Agent or Elena Rogers – NCSU Area Specialized Agent- Food Safety- Fresh Produce at elena_rogers@ncsu.edu or call or text at (828)352-2519. 

The representative for BioSafe Systems for Western NC is Ray Austin. Ray’s contact information is email raustin@biosafesystems.com and phone (561)490-5728.

Summary

• Protecting public health and supplying fresh produce is a priority for the produce industry.
• City/municipal water can be used for pesticide sprays however if there is a boiling water notice in your area consider treating the water before proceeding. 
• If the water source for spray water is a well, have the water tested to ensure the water is of adequate sanitary quality. Test at least 1L of water. 
• At this time we strongly recommended AGAINST using SURFACE WATER as water sources for pesticide sprays.
• Water treatment with OxiDate 5.0 is a viable solution to address current concerns with water quality and prevent contamination of fresh produce that will soon be harvested.

Authors

Elena Rogers, Area Specialized Agent, Food Safety- Fresh Produce for Western NC, Department of Horticultural Sciences, NC State University

Dr. Sara Villani, Extension Specialist, Apple, Grape and Ornamental Plant Pathology, Department of Plant Pathology, NC State University

Dr. Bill Hunt, WNR Professor, Extension Specialist, Stormwater Management and green infrastructure, Department of Biological and Agricultural Engineering, NC State University

Karen Blaedow, Henderson County Extension Agent, Agriculture- Vegetable and Small Fruit, N.C. Cooperative Extension

Dr. Wayne Buhler, Professor and Extension Specialist, Pesticide Education, Department of Horticultural Sciences, NC State University 

Dr. Trevor Suslow, Professor Emeritus, Department of Plant Sciences, University of California Davis