How to Submit a Sample

Submitting a sample

Samples can be dropped off or mailed to ISU Plant & Insect Diagnostic Clinic. All samples must be accompanied by a sample submission form. We suggest to avoid mailing samples on Thursdays or Fridays to prevent packages from sitting in the mail over the weekend, which can impact sample quality. Photos accompanying plant samples are encouraged and can be sent to pidc@iastate.edu

Dropping off a sample? Deliver the sample to the ISU Plant & Insect Diagnostic Clinic between 8 a.m. and 4 p.m. Monday through Friday.

REMINDER: We do not do herbicide residue testing or soil/plant nutrient analyses. 

Mail or deliver samples to: 

ISU Plant & Insect Diagnostic Clinic
2445 ATRB
2213 Pammel Dr. 
Ames, IA 50011

Tips for sample packaging and submission (plant tissue)

How to take photos of plant problems

Select your sample type: 

  1. Pine/spruce, evergreens
  2. Small fruits and fruit trees
  3. Deciduous trees and shrubs
    1. Leaf spots
    2. Canker problems
    3. Root rot problems
    4. Vascular wilts (including oak wilt, verticillium)
  4. Annual (herbaceous) plants, including vegetables
  5. Field crops
  6. Turfgrass/lawn 
  7. Insect/arthropod identification
  8. Soybean cyst nematode
  9. Corn nematodes 

Pine/spruce, evergreens

Needle/twig problems:

Pine wilt

  • Testing for pine wilt nematode requires branches that are at least 2-3 inches across (in diameter) and at least 12 inches long. 
  • We cannot test for pine wilt with small branches or needles. 
  • Branches should be selected from segments of the tree exhibiting early symptoms of pine wilt (i.e., yellowing needles).
  • If the tree has already been cut down, we can also accept wedges from the lower trunk for analysis. 
  • Tips for sample packaging and submission

Small fruits and fruit trees

  • Select plant tissue with symptoms that are starting, developing, and developed. 
  • Avoid sending samples with advanced symptoms or completely dead/wilted tissue. 
  • Avoid sending detached leaves as they dry out very quickly.
  • Wrap specimens (twigs with leaves attached, branches, and/or fruit) in clean, absorbent material (such as paper towels) to absorb moisture. 
  • Do not add moisture. 
  • Print and fill out a sample submission form completely, noting any cankers or cracks in twigs, branches, or the trunk, or gummy material oozing from them.
  • For wilts, root rots, and cankers, see: Vascular wilts, Root rot problems, or Canker Problems 
  • Tips for sample packaging and submission

Deciduous trees and shrubs

Trees and shrubs can have various types of plant health problems. Determine whether your plant has leaf spots, canker problems, root rot problems, or vascular wilts and follow the respective guides below.            

Leaf spots

  • Collect several twigs with leaves attached.
  • Pack the twigs in clean, absorbent material (such as paper towels or newspapers) to absorb moisture, and place in a plastic bag. 
  • Tips for sample packaging and submission

Canker problems

Root rot problems (shrubs)

  • Some diseases affecting leaves might actually be caused by pathogens located in the roots and crown
  • Contact us with photos (pidc@iastate.edu) so we can discuss whether the symptoms you’re seeing warrant sending a sample of the root ball and crown.
  • For root rots and crown disease confirmation, digging up the root ball with some stems (crown) provides the best tissue to recover a suspected pathogen.
  • Leave soil in tact with the roots/crown for mailing or drop off.
  • Tips for sample packaging and submission

Vascular wilts (including oak wilt, verticillium)

  • Observed wilting symptoms? (plants losing leaves from the top of the canopy or one side of the crown, leaves turning yellow and dropping prematurely). Follow tips below.
  • Gather samples from branches that are partially wilted, with symptomatic leaves starting at the branch tip progressing towards the trunk. 
  • Avoid branches that are completely wilted, dry, or dead. These are not ideal for diagnostics. 
  • Select at least three samples from the branches identified with the symptoms above. 
  • Branches should be at least 1 inch in diameter and be cut to 6-8 inches long. 
  • Cut branch samples should be bagged and refrigerated (not frozen) until delivered to the ISU Plant & Insect Diagnostic Clinic.
  • If mailing, samples should be packaged with cold packs in an insulated container and shipped overnight Monday through Thursday. 
  • Sampling for oak wilt? Check out our oak wilt sampling checklist
  • Follow the general tips for sample packaging and submission.

Annual (herbaceous) plants, including vegetables

  • Observe and document symptoms and patterns of symptoms (within a plant and across plants of the same type)
  • Document important background information, including date symptoms first appeared, cultivar, etc. 
  • Collect samples 
    • BEFORE applying pest/disease-controlling chemicals
    • From areas where symptoms are starting, developing, and developed
    • Avoid samples with advanced symptoms, completely wilted, or with dead tissue
  • For seedlings samples: 
    • Send whole plug trays, leave plugs in the tray. 
    • Individual seedlings: make sure to keep root ball and any media contained in a plastic bag or foil.
  • If potted
    • Bag and seal at the soil line, securing with a rubber band, twist tie, or zip tie. 
    • Use another bag for the aerial plant parts, but do not cut the root ball off of the above-ground plant parts. 
    • Include 3-5 plants. 
  • In the field/ground: 
    • Dig around the roots instead of pulling plants out. 
    • Shake most the soil off the roots. 
    • Bag roots and above-ground plant parts separately, securing with a rubber band, twist tie, or zip tie. 
    • Include 3-5 plants.
    • Do not cut the root ball off of the above-ground plant parts. 
  • Pack your wrapped sample tightly to prevent dislodging soil. 
  • Ship overnight, if possible, early in the week. 
  • Follow the general Tips for sample packaging and submission.

Field crops

  • Observe and document symptom distribution (within an individual plant and across a field). Take photos!
  • Collect several samples from 1. where symptoms are starting, 2. symptoms are developing, and 3. where symptoms are developed. 
  • Avoid plants with advanced symptoms or completely dead plants. 
  • Submitting whole plants- contain the roots with soil in a separate plastic bag, secured via rubber band, twist tie, or zip tie, to avoid contaminating the rest of the plant. 
  • Seedlings: send several whole plants, roots and all. See video on sampling for seedling disease.
  • Foiliar diseases: Send 6-10 leaves showing disease symptoms in varying severity. 
  • Root rots: Collect 2-3 whole plants. Dig rots out of the ground rather than pulling. Package roots within a plastic bag secured with a rubber band, zip tie, or twist tie to avoid contaminating the above-ground plant parts. Do not cut the stems from the base of the plants. Here’s a video about collecting whole plants for plant problem diagnosis.
  • Follow the general Tips for sample packaging and submission.

Turfgrass/lawn

  • Observe and document symptoms and patterns of symptoms, including photos.
  • Collect sample 
    • BEFORE applying any disease/insect-controlling chemicals
    • From the edge of the affected area
  • Include both healthy and infected plants, avoiding completely dead grass.
  • Take a sample of at least 6 inches in diameter, including the underlying soil and root system. (A cup cutter works well).
  • Two of these samples are preferred (no extra charge). 
  • Wrap the sample in a newspaper or paper towel, and wrap that in foil. 
  • Avoid using a plastic bag and adding water as it will deteriorate the sample.
  • Follow the general Tips for sample packaging and submission.

Insect/arthropod identification

  • Collect multiple (6-12) insects, if you can. 
  • Insects, spiders, etc. should be dead when shipped (you can freeze them overnight to kill them.)
  • Mail insects in a bottle, box, or padded envelope. 
  • Soft-bodied insects, such as caterpillars and aphids, can be preserved in hand sanitizer gel or rubbing alcohol. 
  • Hard insects, such as moths, butterflies, beetles, ants, spiders, mites, and ticks, do not need to be preserved, but they should be restrained inside the container so they don’t bounce around during shipment (for example, secure a moth or butterfly down with layers of dry paper towel.)
  • Mail samples in a padded mailer or box to protect against crushing. 
  • Print and fill out a sample submission form completely.
  • Send any photos to accompany the sample to pidc@iastate.edu

Human parasites: We will NOT examine skin, hair, scabs, excrement, urine, or other bodily fluids for insects or mites. Scabies and other potential human parasites must be diagnosed by a medical doctor. 

We can identify the following human parasites: ticks, lice, fleas, bird mites, and bed bugs. Small insects must be taped to a white piece of paper and circled. 

Insect/Arthropod Photo Submission Instructions

Soybean cyst nematode (SCN)

If your sample is from outside of Iowa, do not submit it without contacting us first (515-294-0581). We have strict limitations on soil movement. 

When to sample: 

  • In fall after harvest and before the soil freezes.
  • In spring, before planting, after the ground has thawed and drained. 
  • During the growing season, from near stunted and/or yellow soybeans

How to sample: 

  • Collect a soil core or ¼ cup of soil from 10 to 20 different locations in an area no larger than 10 to 20 acres using a soil sampling probe, hand towel, or shovel. 
  • sampling map
    Nematode soil sampling patterns for crop fields with unique features.

    Define the sampling areas within a field by agronomic, cropping history, or other logical features (see figure) or divide the field to be sampled into evenly sized areas if conditions are similar throughout the field. 

  • Take care not to sample only from “hot spots” or areas of severely damaged plants. 
  • Collect soil from the top 8 inches directly in the root zone (if in season and soybeans being grown). 
  • Combine all the sub-samples in a bucket and mix the soil thoroughly. From the mixed soil sample, place approximately 1 to 2 cups of soil into a plastic bag or paper soil test bag. 

Shipping SCN samples: 

  • Place each soil sample in a separate, sealed plastic or paper soil sample bag. 
  • If roots are being collected, place them in a separate plastic bag. 
  • Use a permanent marker to label each bag with the grower’s name and either a field name or sample number that corresponds to the information on the front of the sample submission form. 
  • Protect the samples from temperatures above 80 degrees F. 
  • Do no be physically rough with the samples (by dropping or throwing them in a box or cooler, for example). 
  • Print and fill out the Nematode Sample Submission Form completely.
  • Deliver or send the samples for processing as quickly as possible. 
  • Avoid shipping on Thursdays and Fridays so that samples do not sit in mail trucks over the weekend. 

Corn nematodes

The PIDC provides identification and counts of the nematodes that feed on grasses (corn and turfgrass). We provide information about the nematode species, thresholds, and management information.  We can also identify nematodes on other plants, but please contact us for specific sampling instructions.

If your sample is from outside of Iowa, do not submit it without contacting us first (515-294-0581). We have strict limitation on soil movement.

How to collect samples for vermiform nematode counts: 

  • Corn: 
    • Best time to sample is between V6 and V12, but can be done up to R3. 
    • Read this for more information.
    • Collect 10 or more 12-inch-deep soil cores from the root zone of stunted plants. 
    • Do not mix, break up, or otherwise disturb the soil cores. 
    • If before V6 corn growth stage, also collect 5-10 root masses from plants; the tops can be cut off and discarded. 
    • Keep the sample out of the sun and cool prior to shipping (refrigerator)
    • Follow packaging/shipping guidelines below
  • Turf: 
    • Take soil samples with a soil probe, not a cup cutter/.
    • Take 10-20 soil cores about 4-6 inches-deep, as deep as grass roots. 
    • Keep the sample out of the sun and cool prior to shipping (refrigerator)
    • Follow packaging/shipping guidelines below.

Packaging/shipping corn and turf nematode soil samples: 

  • Place cores into a sealable plastic baggie, keeping samples from different areas separate. 
  • If the weather is hot, ship samples overnight. 
  • If roots are being collected, place in a separate plastic bag. 
  • Use a permanent marker to label each bag with county soil collected in, a field’s name or sample number that corresponds to the information in the front of the sample submission form.
  • Avoid being physically rough with the samples (i.e. do not drop or throw them.)
  • Deliver or send the samples for processing as quickly as possible and avoid sending samples on Thursdays or Fridays to prevent the samples from sitting in the mail over the weekend. 

Tips for sample packaging and submission 

  • Print and fill out a sample submission form completely.
  • Send any photos to accompany sample to pidc@iastate.edu or print and include with submission form. Photos showing tree location, whole plant appearance, close ups of twigs, trunks, and any cracks or cankers on the trunk or plant are helpful. 
    Tips for taking photos of plant problems
  • Place the sample either directly into a box or into a plastic bag and then into a box. 
  • Whole plant sample: bag the roots separately from the above-ground plant tissue to avoid soil contamination of the above-ground plant tissue. Secure with rubber band or zip ties.
  • Place bagged sample in a box for drop off or mailing.
  • Put the sample submission form in the box.
  • DO NOT add water or excess moisture to the sample.
  • Dropoff: deliver to the ISU Plant & Insect Diagnostic Clinic between 8 a.m. and 4 p.m. Monday through Friday. 
  • If mailing the sample, avoid sending the sample on a Thursday or Friday to prevent the sample from sitting in the mail over the weekend.
  • Do not send payment with your sample. You will receive a statement from Iowa State University after you receive a diagnostic report from the PIDC.