Plants collected from home gardens can be kept in your refrigerator. Plants collected in a remote location should be placed in a cooler with ice. DO NOT place samples on your car or truck dashboard as they can overheat and deteriorate very rapidly. Keep foliage from becoming contaminated with soil. Wash roots gently to remove soil unless the sample is to be tested for nematodes or you are submitting a potted plant.
Soil contains many microorganisms that can readily colonize dead or dying tissue.
When removing soil from roots, DO NOT scrub the roots as this can lead to the loss of root tissue that may be important in disease diagnosis. Collect other important information. The diagnosis process often involves piecing together many different clues. Background information is crucial. Pieces from the living sections of branches that are partially alive and partially dead are best.