Plant Disease Clinics

Several plant disease clinics in the Pacific Northwest can help diagnose plant problems. Publicly supported clinics are listed below. A listing of other laboratories (mostly private) that provide a similar service can be found at:

For best service, for the most useful returns on your efforts, and for efficient use of our time, please read and observe these instructions before submitting specimens.


  • Select material showing the symptoms you are concerned about. Send several samples showing various stages of disease, especially early symptoms. If possible, also send a healthy sample.
  • Get all parts of plants, including roots where practical. Enclose roots and soil in a plastic bag. Use another bag to enclose the rest of the plant.
  • If it is not practical to send the entire plant, include several affected portions of the plant. With stem or branch disorders, be sure the sample includes live material as well as the diseased portion. In other words, include the margin between healthy and diseased tissue.
  • If a vascular wilt such as Verticillium wilt or Dutch elm disease is suspected, send several branch sections 1 inch in diameter and about 6 inches long from branches with dying, wilted, or yellowed leaves. Do not send dead wood. Put samples in a plastic bag to prevent drying.
  • Turfgrass samples should be taken from the edges of affected areas that include dying and also apparently healthy plants. Send one or two 3-by-3-inch squares of sod containing 1 inch of attached soil. Wrap each sample in one thickness of slightly dampened toweling, then in dry newspaper. Send as much information as possible.
  • Fleshy specimens such as mushrooms, fruit, or potatoes should be as firm as possible and show early and intermediate symptom development. Wrap specimens separately in paper towels or newspaper. Do not put in plastic. Pack with sufficient padding to avoid crushing.


  • Keep plants cool and moist before shipping. Bag roots separately to keep soil from the rest of the plant, then enclose the entire plant in plastic to keep from drying out. Mail as soon as possible after collection. Mail specimens early in the week to avoid delay in the post office over weekends or holidays.
  • Pack in a sturdy container to prevent crushing in transit. Use packing material to pack the specimen firmly in the container.
  • Identify package with labels both outside and inside. Put the label and the Plant Disease Form in a waterproof plastic bag.

Addressing Packages

Oregon (from any location)
Plant Clinic, Cordley Hall Room 4120, 2701 SW Campus Way, Oregon State University, Corvallis, OR 97331-2903 (Sample forms, fee information, directions to the Clinic, and other info about the OSU Plant Clinic is available at:

Oregon (Northeast Oregon and North Central only)
Extension Plant Pathology Laboratory, 2121 S. First, OSU, Hermiston, OR 97838.

Plant Samples, Kimberly Research and Extension Center, Kimberly, ID 83341

Plant Samples, Parma Research and Extension Center, University of Idaho, Parma, ID 83660

Western Washington
WSU Puyallup Plant Clinic, 2606 W. Pioneer, Puyallup, WA 98371-4998. (Fees required.)

Eastern Washington
Plant Pest Diagnostic Clinic, Dept. of Plant Pathology, P.O. Box 646430, Pullman WA 99164-6430. (Fees required.)

British Columbia
Plant Diagnostic Laboratory, British Columbia Ministry of Agriculture, Fisheries, and Food, 1767 Angus Campbell Rd., Abbotsford, BC V3G 2M3 Canada (Fees required).


Fill out the appropriate Plant Disease Form or Plant Disease Identification Request sheets with as much information as possible. These forms are available in your county Extension offices, the labs listed above and on the web at:

This information is valuable as an aid to diagnosis. Some labs will not process samples unless a form has been filled out. Photographs or even video tapes convey a lot of information that may be useful. The more information you provide, the more accurate the diagnosis will be.

Note: neither the OSU nor the WSU clinics are allowed to accept cannabis samples due to university regulations. However, The Oregon Department of Ag Plant Health can provide disease diagnostics services for both the industrial hemp and marijuana industries. Cannabis samples for diagnosis must be submitted in person.