If you believe your plants have been damaged by herbicide drift, it is critical to document your observations immediately, carefully, thoroughly, and repeatedly. Growers affected by drift damage have important decisions to make on how they will respond, but all of these options hinge on documenting damage and related observations.
- Note the date and time of application, the name or a description of the applicator if possible, crops or conditions of the sprayed field (soybeans, fallow ground, etc.), along with any equipment you observed.
- Use photos, videos, and notes to document a possible infraction (spraying during high winds or after a state cut-off date, for instance).
- Document weather conditions for the spray event and the 3-5 days following application. (If the spray event was not observed, document weather for the week before drift damage was noticed).
Plant tissue damage caused by a drift event can be alarming. Remember that foliar damage does not always result in reduced yield or permanent damage, but you will not get a second chance to collect photos and data. Play it safe and document any damage (or questionable spraying events) as soon as you see it. Symptoms of 2,4-D and dicamba injury may appear within a few hours after contact with drift or within a few days. Severity and timing of injury depends on the concentration of drifted product, the transpiration rate of affected plants, and the relative sensitivity of the non-target crop.
- When documenting damage, include the date and the growth stage of affected plants. Use drawings, video, and photographs to record what you see.
- Record the development and progress of symptoms over time.
- Indicate the locations of observed symptoms using a reliable to-scale map of your farm and surrounding area. (If you don’t already have a map you can use a satellite service such Google Earth to create one.)
- Note field elevation. Runoff from a treated adjacent field can be a cause of damage, and drift influenced by temperature inversions tends to settle in low spots.
- Collect plant or soil samples and photos quickly. Initial tissue damage may become less evident as new growth replaces it and herbicide residues can break down or wash away.
- Err on the side of collecting too much detail and data. Photos, notes, and samples are easy enough to delete if not needed. Below are some additional tips.
Photographs and Video.
- Add time and date stamps on any photos or videos.
- Use GPS stamping if you have it (available on most smart phones). If not, include landscape features (hills, silos, windbreaks, buildings) to help establish location.
- A coin or similar consistently sized item can provide scale if needed. Video showing the movement of a piece of paper or grass blades can document wind direction and speed.
- Video with commentary can be an easy way to capture visuals and notes together.
- Photograph the whole plant and successive close-ups of damaged areas. (See photos)
- Use landscape shots to show the extent of damage across the field.
- Photograph the various severities of damage, including healthy plants in the same growth stage. Note the location for each.
- Photograph non-crop plants that show suspected damage. If you observe a clear path of damage, use photographs or video to document this.
- If you have access, a drone can effectively photograph patterns of damage and symptoms that might be missed from the ground level.
Rule out alternative explanations. Sample collection and other documentation is time sensitive but also time consuming. Enlist help from a resource guide and/or crop expert as soon as possible to rule out alternative causes of suspected drift injury.
- Examine the plants for insects as well as their casings or feeding marks. Some insect damage may resemble dicamba and 2,4-D damage (e.g., aphids may cause leaf curling, leaf hoppers may cause leaf burn.)
- Soybean mosaic virus can cause leaf cupping and bumpy leaf surfaces.
- Some fungicides and fertilizers, such as foliar urea, can cause leaf burn.
- Fertility deficiencies or water stress may cause chlorosis.
- If the damage happens early in the season, check weather records to rule out a frost event. Frost might damage exposed or developing leaves and buds. In this case, damage may be concentrated in low areas of your field.
- Could herbicide damage have come from your own operation? Many lawncare products contain 2,4-D, and other herbicide products may cause similar symptoms.
Crop consultants, extension specialists, experienced farmers, or other knowledgeable individuals may be able to help you rule out alternative explanations and provide advice such as steps to take and additional resources. Don’t wait too long to ask for their assistance.
Be aware that herbicide disputes can create awkward situations for local farm service agencies (county extension, Farm Bureau, Soil and Water Conservation Districts, etc.). However, farm service providers, other growers, crop insurance companies, and grower associations may be able to put you in touch with appropriate legal and expert assistance.
Plant Tissue Samples. If you are filing a state complaint or insurance claim, their respresentatives will want to collect samples, but you should also collect your own samples. Familiarize yourself with private labs and their specific requirements for sample collection, storage, and documentation. Involving a certified crop advisor, extension employee, or other impartial third party will avoid claims of biased sampling or procedural error.
If you do not have specific directions from your testing lab, follow these guidelines and collect samples as quickly as possible.
- Collect more than you think you will need. If the size of the field allows, collect several gallon-sized bags of plant tissue. Collect a mix of older and newer leaves, as well as stem and roots if possible.
- Use laboratory gloves to take samples, if available, starting with a fresh pair for each new area to provide cross-contamination.
- If there is a clear progression of damage in your field, sample from these areas separately. Include a sample of healthy undamaged plant tissue, using the same collection and labeling techniques for all.
- South Dakota Agricultural Labs recommends using perforated paper bags to prevent molding. Secure the bags well and keep them dry.
- Label all bags with date and time, field location, and the name of the person who collected the sample. Add crop variety or growth stage if it varies on your farm.
- Plant samples should be frozen as soon after collection as possible and sent to the analytical lab on dry ice.
- Prepare at least one aggregate soil sample from an affected area. Mix together multiple samples from similarly damaged spots. Use the first 0-6” of topsoil (first 3” for an untilled field). Mix these together in a large bucket and submit a subsample of the mixture to a lab. Soil should also be frozen for storage and/or shipping.
- Track all employees who collect and handle each sample along with how and where samples are stored.
Look for, and document patterns of crop injury. Crop injury from herbicide drift usually varies across a field depending on wind speed and direction, natural and man-made wind breaks, slope and lay of the land, etc. Patterns of damage can offer clues about how and where the drift entered the off-target field.
- Does the damage affect the entire field? Is it worse on one side or in low-lying areas?
- Walk the perimeter of the field and look beyond it if possible. Can you trace the direction the damage came from? Look for damage to plants in hedgerows, landscapes, meadows, yards, or other adjacent areas. Common plants that might show damage include broadleaf weeds, wild grapes, wild or cultivated roses, maples, dogwood, and oaks. Don’t forget to look up; you may spot foliar damage in the tree line.
- Look for patterns over time as well. See what changes in the coming weeks and keep a log of observations. Does the damage get worse or better? Dicamba and 2,4-D will generally move to new growth on affected plants, but rarely to adjacent areas of the field (unless another drift event occurs).
- Follow observations through harvest if appropriate. Not all types of damage are apparent immediately. Drift damage may have an impact on fruit ripening, yield, or cold hardiness in perennials. In soybean and potatoes, herbicide damage symptoms have been noted in plants grown from seed or tubers of damaged plants. (Jones et al. 2018; Geary et al. 2019).
Track Your Investigative Process
- Keep all reports from testing or on-site visits. If an expert comes out to examine your field, make sure you get something in writing from them in case you need it later. They may or may not be able to provide these for you several months after their visit.
- In addition to reduced yields, keep records on claims and losses under applicable contracts, lost crop premiums, testing, consultant fees, and other expenses related to the incident, including time spent by employees and yourself documenting or managing the damage.
- Detailed notes of any conversations, phone calls, or correspondence related to the incident should be retained.
- Special note on phone calls: In some (but not all) states it is legal to record conversations if at least one of the participants is aware of the recording. Either way, it’s a good idea to inform the other person you are recording. In states where this is required, be sure to also record the other persons’ verbal consent to record.
This publication is a product of the North Central IPM Center working group on Herbicide-Drift Risk Management, with support from the USDA National Institute of Food and Agriculture through agreement 2018-70006-28884.
Reference to any commercial products or trade names implies no discrimination or endorsement by the North Central IPM Center or any of the contributing authors or their universities. Nor does this document constitute legal advice. Always seek legal advice from a professional who is knowledgeable in current agricultural law in your state.
Cassandra Brown, Horticulture and Crop Science, The Ohio State University
Stephen Meyers, Horticulture & Landscape Architecture, Purdue University
Mary Ann Rose, Pesticide Safety Education Program, The Ohio State University
Douglas Doohan, Horticulture and Crop Science, The Ohio State University
The following individuals reviewed part or all of this fact sheet: Bill Johnson, Purdue University; Cathy Herms, Maria Smith, Peggy Kirk Hall, The Ohio State University; Steve Smith, Red-Gold; Regina Wixon, South Dakota Agricultural Laboratories; Pat Farquhar, Sydney Ross, North Carolina Department of Agriculture; Pesticide Enforcement and Compliance Assurance Section staff, New York State Department of Environmental Conservation; Minnesota Department of Agriculture Pesticide and Fertilizer Management Division.
Behrens R, Lueschen WE (1979) Dicamba volatility. Weed Sci. 27:5, 486-493.
Bish M, Bradley K (2017) Survey of Missouri pesticide applicator practices, knowledge, and perceptions. Weed Technol. 31:2:165-177, doi:10.1017/wet.2016.27
California Pesticide Use Enforcement Compendium Vol 5 Investigation Procedures. Chapter 3 Evidence Collection https://www.cdpr.ca.gov/docs/enforce/compend/vol_5/invstprc.htm
Geary ND, Hatterman-Valenti H, Secor GA, Zollinger RK, Robinson AP (2019) Response of ‘Russet Burbank’ seed tubers containing dicamba and glyphosate. Weed Technol 33:1, 9–16. doi: 10.1017/wet.2018.91
Jones GT, Norsworthy JK, Barber T. (2018) Response of soybean offspring to a dicamba drift event the previous year. Weed Technology 33:1, 41-50.