University of Missouri Extension

F260, Reviewed January 2017

Plant Diagnostic Clinic: Guidelines for Collecting and Submitting Samples

Collecting plant disease samples


Plant Diagnostic Clinic
28 Mumford Hall
Columbia, MO 65211

Blossom end rotFruits or mushrooms

Select fruits with early symptoms of disease, not those in advanced stages of rot. Wipe away excess moisture, and wrap individually in a dry paper towel. Do not place in a plastic bag. Place samples in a crushproof container with packing material to prevent movement. Ship perishable items for next- or two-day delivery.

Insect damageLeaf spots

Collect 10 to 20 leaves showing all stages of the symptoms. Highly succulent leaves should be treated like other fleshy tissue samples. Place leaves between cardboard or heavy paper, or submit leaves still attached to a branch.

yellowingYellowing and general decline

Submit entire plant if possible. Wrap roots, including soil, in a plastic bag, but leave the top of the plant exposed.


Dig up two plugs at the margin between healthy and affected turf. Plugs should contain two-thirds symptomatic and one-third healthy turf. Each plug should be 4 inches by 4 inches and should include 4 to 6 inches of soil. Wrap plugs individually in aluminum foil to enclose the soil, but leave the foliage uncovered.

Tree declineTree wilt

Collect samples from symptomatic branches. Do not collect from dead branches. Branch sections should be ½ to 1 inch in diameter and about 6 inches long. Place branch samples in a plastic bag to retain moisture. Also submit leaves from the branch, pressed between cardboard or heavy paper.

Butternut cankerStem lesions, diebacks, cankers and galls

Select branches with active lesions or young galls. Cut branches or areas that include healthy as well as affected tissue. Dead branches and healthy, unaffected branches are usually not suitable for diagnosis. Call if the canker is on the trunk or a branch too large for shipping.

Collecting plant and weed ID samples

PlumWoody plants (trees, shrubs, woody vines)

Herbaceous plants (plants with green or soft-tissue stems that die back each year) or grasses

Collecting insect or arachnid samples

Packing materialFor shipment

Packaging plant samples

ShippingPackaging regular samples

Pack plant problem samples in sturdy boxes with enough packing material to prevent excessive movement. Damage during shipment can change a good sample to a poor one. Do not ship samples in an envelope.

Delays in mailing can cause deterioration of plant samples. Mail samples early in the week to avoid delaying delivery over a weekend. For highly perishable items, always consider overnight delivery. 

Regular sample packaging, right. Enclose roots and soil in a plastic bag before shipping.

Packaging regulated pest samples

Suspected pests of regulatory concern, such as thousand canker disease or soybean rust, require special handling and packaging to prevent the spread of pathogens. Place a sample inside a sealed plastic bag with a dry paper towel. Then seal the first plastic bag inside a second sealable bag.

Packaging regulated pest Place the double-bagged sample inside a sturdy box, and add packing material to reduce movement. Seal all seams of the box with packaging tape. Samples should be hand-delivered or sent by overnight delivery to the clinic. As a last step, notify the clinic that a package of regulatory concern has been shipped.

Regulated pest packaging, right. Double-bag samples of regulated pests.

Diagnosis and reporting

Diagnosis of plant damage requires examination and testing to detect disease-causing pathogens on plant material. The clinic also checks for insect pests and assesses damage that may have been caused by nonliving agents.

Weeds and insects are identified based on physical characteristics. When plant problems are caused by cultural or environmental conditions, determining the exact cause may not be possible. However, when enough information is included, the clinic can suggest possible causes for the damage identified in the diagnosis.

After a diagnosis is made, reports are returned by ­email, fax or mail.

The Plant Diagnostic Clinic cannot do the following




Fees subject to change.


The Plant Diagnostic Clinic submission forms are designed to provide the information necessary for the clinic to provide a complete, accurate and timely diagnosis or identification of samples and to provide appropriate control recommendations. Submission forms are available at your local county extension center or online at

Samples may be submitted directly to the clinic or through county extension centers. On the web, see for the the center nearest to you.

The clinic must receive a physical sample or photographs and a completed diagnostic submission form before an accurate diagnosis can be made and treatment recommendations given.

F260 Plant Diagnostic Clinic: Guidelines for Collecting and Submitting Samples | University of Missouri Extension

Order publications online at or call toll-free 800-292-0969.

University of Missouri Extension - print indicia