NMSU: How to Collect and Send Plant Specimens for Disease Diagnosis
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Authors: Respectively, Extension Plant Pathologist and Plant Diagnostic Clinician, Department of Extension Plant Sciences, New Mexico State University.

Successful plant disease diagnosis is a team effort. Proper diagnosis begins with the submission of a good-quality specimen accompanied by accurate and complete information. It is difficult, if not impossible, to determine the cause of death from a single leaf, dried or old specimen, or (especially) a dead plant. Healthy plants from the same area are also helpful to a diagnostician. It is also important to include the margin of the disease (where healthy and diseased tissue come together) in the sample, especially with stem and branch disorders.

Guidelines for submitting specimens to the plant diagnostic clinic for diagnosis

Please read and follow these instructions before submitting specimens.

Collecting

  1. Provide as much information regarding the specimen as possible. Fill out a "Plant Specimen Submission" form.
  2. a) Identify the plant material (variety) and acreage (when applicable), and indicate the percentage of plants affected.

    b) Indicate when the symptoms first started and whether or not the symptoms are continuing to develop or spread.

    c) List all cultural practices such as irrigation frequency, rate and time of chemical application (herbicides, insecticides, fungicides, etc.), fertilizer regime, and crop rotation over the previous three years when applicable.

    d) Try to give an estimate of the weather conditions preceding and during symptom development.

    e) For home or urban plantings, indicate the type of environment in which the plant is growing (e.g., lawn, flowerbed, pot, house, greenhouse).

    f) Good-quality, in-focus photographs or digital images of the plant in its environment can be extremely helpful to the diagnostician. Digital images can be sent via e-mail to:

          ngoldber@nmsu.edu
          jfrench@nmsu.edu

    If the images correspond with a submitted sample, please be sure to note that in the email message.

  3. Select material showing the symptoms. If possible, it is best to send several samples showing various stages of the problem. Early stages of symptom development are especially important.

  4. Send samples of all plant parts, including roots whenever possible. Aboveground symptoms may be caused by root or stem diseases; thus, examining all parts can be essential for an accurate diagnosis. Dig plants (do not pull them) out of the soil. Pulling plants out of the soil will generally break off the roots, especially if they are rotten. Retain a small amount of soil around the roots. Do not wash roots. Keep the roots and soil separate from the aboveground parts of the plant by placing them in a plastic bag and sealing them off with a rubber band.

  5. When the entire plant cannot be sent, send several affected portions of the plant. Remember to include the margin of disease on stem and branch samples.

  6. If you suspect vascular wilt diseases, such as Verticillium wilt, send a sample from dying or wilted branches with yellow leaves. Remember: Do not send dead wood. Place several branch sections 1/4 to 1 inch in diameter and approximately inches in length in a plastic bag. This will prevent the sample from drying in transit.

  7. Turfgrass samples should be taken from the edge of the affected area and should include both dying and healthy plants. Again, do not send dead grass. Send several 3 inch x 3 inch squares of sod, which should include at least 2 inches of soil. Wrap the sample in a thin layer of damp (not wet) paper toweling, then wrap in dry newspaper.

  8. Fleshy specimens such as fruit, mushrooms, or other fungal fruiting bodies should be as firm as possible and show both early and intermediate symptoms. Wrap specimens separately in dry paper toweling or dry newspaper. Do not put in plastic. Pack specimens so they are not crushed during shipping.

Packing

  1. Keep plants cool and moist prior to shipping. Use an ice chest when collecting samples and then place them in the refrigerator until they can be sent.

  2. Pack in a sturdy container to prevent crushing during transit. Use newspaper to pack specimen firmly in the container. Be sure to include a completed submission form with contact information, including e-mail address if available.

  3. Mail specimens as soon as possible after collection (overnight delivery is recommended). Mail early in the week to avoid delivery delays over weekends, and be aware of holidays that also might delay delivery.

  4. Address packages to:
    Plant Diagnostic Clinic
    Extension Plant Sciences, MSC 3AE
    New Mexico State University
    P.O. Box 30003 Las Cruces, NM 88003–8003

    For Overnight, UPS or Fed Ex:
    New Mexico State University
    Plant Diagnostic Clinic
    945 College Avenue
    Skeen Hall Room N140
    Las Cruces, NM 88003–8003

The diagnosis you receive is only as good as the sample you send. In some cases, diagnoses may require the use of tests or equipment that are not available at our facility. In those cases, commercial laboratories may be recommended. While time devoted to individual samples is limited, diagnostic reports will reflect considered opinion and best judgment based on all the information available. Complete information regarding the sample that is submitted will help the diagnostician provide an accurate diagnosis. For some problems, such as insect damage, other professionals may be consulted. Specimens may be forwarded to scientists more qualified to analyze the material. Remember, proper diagnosis begins with you. Submitting good-quality specimens accompanied by complete and accurate information is the first step in identifying and solving the problem. Your satisfaction may depend on it!


To find more resources for your business, home, or family, visit the College of Agricultural, Consumer and Environmental Sciences on the World Wide Web at aces.nmsu.edu.

Contents of publications may be freely reproduced for educational purposes. All other rights reserved. For permission to use publications for other purposes, contact pubs@nmsu.edu or the authors listed on the publication.

New Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Department of Agriculture cooperating.

Revised and electronically distributed March 2009, Las Cruces, NM.