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Diagnose plant problems with the UMN Plant Disease Clinic

plants outdoors with one leaf that has large brown area in the middle of the leaf
Some problems are difficult to diagnose in
the field.

When growers spot issues on their vegetable or fruit plants, the cause of the problem is often not identifiable in the field. However, identifying the cause is a very important first step to resolving it.

Did you know that the University of Minnesota has a Plant Disease Clinic (PDC) that helps diagnose diseases on plants?

Every year, they receive between 2000 and 2500 samples from growers, and last year these included over 170 different plant species.
Submitting a sample for expert diagnosis at the PDC can save costs by making sure that the appropriate treatments are applied, and by identifying problems before they get too severe or expensive to manage.

Listen: Interview with Brett Arenz, Director of the UMN Plant Disease Clinic, via "What's Killing My Kale" Podcast

How does this work? 

The PDC pathologists use multiple tools to nail down the problem. Beyond visual cues, they can use microscopic analysis, tissue culture, nematode testing, virus testing, and DNA and RNA-based analyses as needed to reach the diagnosis.

Many of the more common diseases can be identified with a routine diagnosis. This includes traditional symptom analysis, microscopic examination and serological tests when applicable. For more difficult samples, the clinic may recommend additional testing techniques as appropriate. Fees differ according to the complexity of the tests performed.

Submitting a sample

The quality of the sample plays a big role in successful diagnosis. Here are several tips for submitting a sample:
  • The sample must include living tissue where the symptoms are currently appearing.
  • Include adjacent healthy tissue for comparison.
  • Pack the sample in a plastic bag, not paper, to prevent drying.
  • Mail the bagged sample in a shipping box, and include this submission form.
  • Provide as much information as possible on the submission form. 
    • Environmental factors and description of the issue help inform the diagnosis.
    • Additionally, some symptoms that look like disease may actually be caused by something else.
    • Describe the symptoms, severity and area of infection, the farm site, and current and past management practices.
  • If you suspect certain diseases based on past occurrence or conversations with other experts, it is a good idea to list those on the form in the "Problem" box.

To ship the sample: Samples should be packed in a plastic bag, then inside a box, and should include the completed form and a check for the analysis fee.

Refer to the PDC website for specific information on services, sample submission, and fees.

The PDC can be reached at

—Annie Klodd, Extension educator, fruit and vegetable production

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