- A single sample may not be enough for accurate diagnosis. Choose multiple plant/leaf/fruit samples that demonstrate early, middle, and late stages of disease progression.
- Stem and branch specimens should be 8 to 12 inches long, and include diseased and healthy areas.
- Do include samples representative of the overall plant population in the field.
- If plants show wilting, yellowing, stunting, or general decline, collect the entire plant including root stem. Dig plant carefully from the ground—do not pull out—so that the root system remains relatively intact, and shake away excess soil. Enclose the root system in a plastic bag, and the rest of the plant sample in another plastic bag.
- Check that root samples are from affected plants, not adjacent weeds.
- For lawn and turf diseases, submit a 3 to 4 inch diameter plug containing both diseased and healthy turf tissue.
- Do not sample dead/dying tissue. If sending a stem sample, check for green tissue under the bark.
- Do not collect leaf or plant samples heavily covered with soil or dust.
- Do not collect samples from plants damaged by insects, animals, agricultural equipment, etc.
- Do not sample plants under moisture or temperature stress.
- Do not add any additional moisture to samples.
- Using a hand shovel, scrape away surface litter, and remove the top 3 to 5 inches of soil.
- Take soil close to the rhizosphere (root) zones of affected plants.
- If collecting soil from multiple sites as a composite, mix in a clean plastic bucket, and send a total of about 500 grams (1.1 pounds) of soil.
- Avoid taking samples from areas such as lime piles, fertilizer spills or bands, livestock congregation areas, poorly drained areas, dead furrows, and areas close to roads or pathways.
- Do not sample especially dry or wet soil.