Herbicide drift can be a big problem – whether you are the drifter or driftee.
When you apply herbicide this year, be sure to document everything possible about the application – the date; time; and weather, not only when you start spraying, but also any changes while you are spraying.
You'll also need complete information about the herbicides applied, the equipment used and how the sprayer was set up – boom height, nozzle selection, spray pressure, etc.
If you suspect your crops have been damaged by drift, you need the same kind of basic information and a lot more.
Be sure to consider the fact that drift may not have come from adjacent field. You may have to gather information from everyone upwind who was spraying.
You also have to rule out other reasons for the symptoms you see on the plants. It's a good idea to collect samples of all the plants – crops and weeds – with symptoms.
You'll need lots of photos. Aerial photos may show you a pattern and point to the likely source. Make sure there is a date/time stamp on the photos.
You'll also have to document what happens to the plants over the growing season. Did they die? Was their growth stunted?
You'll need detailed yield records of damage and non-damaged areas to determine actual losses.
For a complete, in-depth guide to documenting spray drift see NDSU Extension publication WC-751"Documentation for Suspected Herbicide Drift Damage. It contains information on documenting injury and language from North Dakota and Minnesota law about actions that must be taken before a civil action is filed seeking reimbursement for property damage.
The publication is on the web at http://www.ag.ndsu.edu/pubs/plantsci/weeds/wc751.pdf