b'can be detected with photographs of the affected area from multiple viewpoints on the ground and from overhead. See Documentation for Suspected Herbicide Drift Damage, NDSU Extension article WC751 for more details on documenta-tion.Recordhowsymptomsvaryin severitythroughouttheareaorfield. Additionally,documentnon-affected plants as a comparison. Good documen-tation of injury will help identify poten-tialcauses,detectpatterns,anddocu-ment the field area that was originally affectedwhensymptomsbecomeless apparent.Theserecordsareessential whencontactingpartiesinvolved,Figure 1. Sampling bags labelled in field for leaf and tuber samples.insurancecompanies,andthestatemultiple tests. Record GPS location ofple tissue that is showing the greatest department of agriculture. samples to be able to return to the sam- damagetoensurethatthesuspected ple location if needed for yield checks orchemicalcausingtheinjuryisfound. Chain Of Custodymore sampling. For example, if the injury is expressed in Documenting the chain of custody canupper leaves, sample the most injured beimportant,especiallyiflitigationGood sampling starts with clean glovesleaves. Select 5 to 10 plants randomly in couldoccurbecauseoftheherbicideand an unused bag. This will ensure thata grid, zigzag, or X pattern and pick injury. Chain of custody is the chrono- residuesdonotcross-contaminate.off the most injured looking plant tis-logical order of each entity or individualResiduesonbarehandsoronsue. Place all plant material in one bag thattakespossessionofthesample.unchangedglovescaneasilycontami- (sample1).Collectonetotwotubers Some laboratories have a chain of cus- natesubsequentsamples.Remember,from each plant sampled from and put tody documentation template that cantesting procedures can find parts per bil- in another bag (sample 2). If tubers are beutilized.Athirdpartycanalsobelion or parts per trillion. A part per bil- small, collect more to ensure a sample used to verify where and when sampleslion is equivalent to a pinch of salt insize adequate for the laboratory analy-were taken as well as who received the250,000 tons of potato chips (or a pinchsis.Additionally,sampleafewplants samples at each point. of salt in 31 million - 1 oz bags of chips).(sample 3) and tubers (sample 4) from Even the slightest residue could cause athe non-affected areas as a comparison Samplingfalse-positive result. Use disposable latexto ensure the injury symptoms are only Time is of essence because plants workglovesandapaperbagorventilatedin the identified area.rapidlytoremoveherbicides.Iftooplasticbag.Ifaplasticbagisused, much time elapses, symptoms may stillrememberthatpotatoesneedtoGentlywashtuberswithcleanwater be apparent, but herbicides may not bebreathe. If a plastic bag is sealed withoutand air dry or use a clean, soft brush to found as they are broken down into sec- holes,itcanallowthesampletoremove the soil from the tuber. This is a ondarycompounds.Asamplesizeofdegrade, become soupy, and not testablegood time to take pictures of any tuber one pound of material is typically suffi- when it arrives at the laboratoryinjury. If your bag is dirty from the field, cient.Checkwiththelaboratoryforplace samples in a new bag and relabel sample size required for a given test orWhen sampling the injured area, sam- the bag. This will ensure that soil on the 20 POTATO GROWER MARCH 2022'