Extension Plant Pathology Laboratory
Department of Plant Sciences
PO Box 3354 (16th and Gibbon)
University of Wyoming
Laramie, WY 82071-3354
Diagnoses are provided for diseases caused by infectious microorganisms as well as problems caused by our harsh environment. Methods for managing the disease are provided.
If possible, ask your county extension educator to examine the sample first. Your extension educator is often able to diagnose many local pest problems quickly or may notice key features at the site which facilitate diagnosis. If you need to submit a sample, package the sample properly (see below) and complete the sample identification form.
Follow the directions below.
We need information on the name of the plant, the symptoms observed, the cropping or gardening history of the site, irrigation practice, fertilizer and pesticide usage, soil texture, distribution of the problem in the field or yard, degree of soil compaction and so forth. Photographs are very helpful in diagnosis especially for turf and tree problems. Freehand sketches of landscape plantings showing relationships to sidewalks, watering and drainage, the house, and so forth, also reveal possible causes of the disease. Include as much information as possible because this will increase the chances of a rapid and precise diagnosis. Include the EPPL Sample form, available here and at your county extension office along with the sample.
Plant samples should be generous—don’t be afraid to collect a large sample. Include a variety of symptoms, ranging from healthy to severely diseased. Use plastic bags punched with pencil-sized holes to keep the sample moist (not wet), and do not add water. This can deteriorate a sample very quickly.
Small plants should be dug (not pulled) from the soil. Carefully shake the excess soil off the roots, and enclose the roots in a plastic bag that is firmly closed around the lower part of the stem. The roots will remain fresh if the bag is filled with moist (not waterlogged) wood shavings or a similar material to prevent drying. A second plastic bag punched with holes can be placed loosely over the foliage to reduce drying. Place the plant in a sturdy container for shipment and pack it securely with newspaper.
Samples of leaves can be collected by removing a segment of stem that includes the terminal end of the stem. This stem segment with attached leaves should be placed between two sheets of waxed paper. The sample can be held flat by sandwiching it between two sheets of cardboard or stiff paper. This may be enclosed in a plastic bag and mailed in a large envelope or a cardboard box.
Large pieces of stems with cankers (stem lesions) can be wrapped in waxed paper or newspaper, place into a plastic bag and packed securely in a cardboard box. the same procedure can be used for woody root segments that show symptoms of disease.
If a trunk with a canker is too large to remove, carefully look for fungal structures on the canker. These will be very small colored or dark projections over the surface of the diseased area. Sterilize a knife using a disinfectant such as Lysol spray or by soaking it for at least three minutes in a 1:9 mixture of household bleach in water, and remove a small (1-2 inches) section of this area. Cut deep enough to remove the surface of the canker but no deeper. Wrap the sample in a paper towel, waxed paper, or newspaper, and pack it in a suitable container.
Turf samples should be 4-6 inches square and at least 3 inches deep. Collect samples from areas of the lawn that are showing symptoms but that are not completely dead. If there is a clear border between healthy and diseased turf, then the sample should be taken from this border area. Place the sample in a plastic bag and pack it securely with newspaper in a sturdy container.
Select samples in the early stage of decay. Wrap the samples in dry paper towels or newspaper and enclose them in waxed paper, aluminum foil, or a plastic bag punched with holes. Include leaf and stem samples if possible. Pack securely in a sturdy box.
Plant parts that suddenly wilt may be infected with a vascular wilt pathogen. If possible, send the entire plant as described above. If the entire plant is too large to send, several stem or branch sections from a recently wilted plant should be removed and prepared as described above for stem sections. Also, send a sample of the leaves as described above.
Please mail samples early in the week and no later than Wednesday afternoon to avoid spoilage over the weekend.
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