Sending a Plant Sample for Analysis

Last year, the Plant Disease Clinic received over 1300 plant samples for disease diagnosis. Proper disease diagnosis relies on having a good, representative sample. If you need to send a sample to the Clinic, you can take several steps to ensure that you get the most accurate diagnosis possible:

  • For small plants, send the entire plantincluding the roots. Sometimes wilting or discoloration of the leaves is really the result of a root problem.
  • For large plants, send as much symptomatic material as possible. Send a branch cutting rather than just a few leaves.
  • Choose a sample that shows a range of symptoms, from healthy to diseased. We can't do much with a completely dead branch, but a few branches showing the progression from healthy to dead can be very useful. Choose branches or plants that are characteristic of the problem you are seeing.
  • For turf problems, collect a section of the grass (roots and all) from the edge of the affected area, so that some healthy and some diseased grass plants are included.
  • Wrap the sample in dry paper towels or newspapers and do not add water. Put the wrapped sample in a plastic bag so it doesn't dry out. Then ship it in a sturdy box so the sample doesn't get crushed.
  • Ship samples early in the week, so they don't sit over the weekend.
  • Background information is as important as the sample itself. Tell us when you noticed the problem, what symptoms you see, where the plants are growing, what has happened recently around the plants, what chemicals have been used, what pattern of symptoms you see, and what you suspect the problem may be if you have a guess. Fill out the Plant Disease identification form, PD 31.
  • Pictures, from both far away and close-up, can be very helpful, especially for turf problems.
  • There is a $10.00 charge for most samples.

Complete sample

A complete sample including properly packaged plant parts, background information, and photographs.

Having a good sample helps the Clinic to return an accurate diagnosis. More information on sampling can be found in PM 1542, Tips for providing plant and insect samples to ISU. If you have questions about collecting or sending a sample, always feel free to call the Clinic at 515-294-0581.

Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 15, 2005. The information contained within may not be the most current and accurate depending on when it is accessed.