GTI Diagnostic Clinic

The GTI Diagnostic Clinic

The GTI Diagnostic Clinic

The Guelph Turfgrass Institute's Diagnostic Clinic is an invaluable resource to Canadian turfgrass managers and strives to support sound management decisions based on the principles of integrated pest management. Our team of diagnosticians will not only confirm whether the symptoms you are experiencing are biotic or abiotic in nature, they will also confirm the specific pathogen(s) present within the sample. In most cases, received samples can be processed with a response to the client within 24–48 hours, however, on rare occasions, the process may take longer if further steps, such as incubation, are required. When submitting a sample, be sure to read the form carefully and provide as much detail and background information as possible. Pictures are also welcomed. The more information you provide, the higher the likelihood of an accurate diagnosis.

Please keep in mind, the GTI Diagnostic Clinic is not a consulting agency. Our services will offer closure and confirmation on your observed symptoms as well as a list of general management/remediation recommendations for any pathogens found present in the sample. We highly suggest that you discuss results with your agronomic consultant to explore the specific steps and solutions required regarding your unique property and challenges.

The GTI Diagnostic Clinic is currently open and accepting samples

GTI Diagnostic Clinic Hours 

  • For mail-in samples:
    • Tuesday – Friday: 9am – 3pm
  • For drop-off samples (scheduled in advance):
    • Monday 9am – 10am; 12:00 – 1:30pm
    • Tuesday 9am – 3pm
    • Thursday 9am – 1pm
  • All other times are by appointment only, subject to diagnostician availability

GTI Contact Information

Phone: 519-824-4120 x 58873
Text: 519-241-2566

Important Details for Submitting Samples

  • For shipping: To ensure the prompt and secure arrival of your sample to the Diagnostic Clinic, please email us when you have shipped your sample. If possible, include the tracking number associated with the package so that we know when to expect the delivery. We recommend that the packages be labeled "PERISHABLE" so that the sample is handled with urgency by the mail service. 

  • Send Sample to:
    The GTI Diagnostic Clinic c/o Dr. Katerina S. Jordan
    E. C. Bovey Building

    University of Guelph, 50 Stone Road East
    Guelph, ON
    N1G 2W1

  • Include the GTI Turf Diagnostics Submission Form (printable .pdf)

  • Unless the sample is dropped off in-person, we do not recommend sending samples using same-day delivery on Fridays since the Diagnostic Clinic is closed on weekends. 

  • In-person consultations can be scheduled with Dr. Katerina Jordan by appointment, text Dr. Katerina Jordan (519-241-2566) in advance. NOTE: University of Guelph requires visitors to wear medical-style disposable masks when on campus. 

  • In-person drop-offs must be scheduled in advance. Please email us or text Dr. Katerina Jordan (519-241-2566) to schedule a drop-off at the following location: 

    • University of Guelph, E.C. Bovey Building, Room 4224

      50 Stone Road East, Guelph ON

A map indicating the location of the Bovey building at the NW corner of the intersection of Gordon Street and South Ring Road W



Q: Why should I use the GTI Diagnostic Clinic?

A: Although many turf managers have taken classes and sat in on presentations regarding specific disease ID and management strategies, it can be challenging to identify disease symptoms in the field with 100% accuracy. The diagnostics clinic will help to confirm the specific pathogen(s) present to ensure you are taking the most appropriate action for the problem at hand. In many cases, when clients feel they have a disease, it is often an abiotic issue - meaning there are no pathogens causing the problem and rather the issue is related to environmental stresses such as drought, heat, traffic, shade, or poor management decisions.


Q: Why are there no longer any association discounts?

A: In the past, the GTI Diagnostic Clinic received subsidies and funding from industry associations in order to help sustain operations and provide reduced costs to members of their associations. The clinic no longer receives any industry subsidies or donations and therefore we are challenged to find a price point that is reasonable to clients but economically viable for the clinic. If you are interested in supporting the clinic or wish to further understand how the GTI Diagnostic Clinic operates, please be sure to contact the GTI Communications and Outreach Coordinator by email at or by phone at 226-971-1563.


Q: Why does my report list multiple pathogens in the diagnosis?

A: In many cases, pathogens are always present in the soil. Although not all of them may be threshold levels that be the primary candidate of your symptoms or issues, those pathogens may still be playing a smaller role in the total stress the plant is under. As a result of this cumulative stress complex, some of the other pathogens will be listed so that you are made aware of their presence. This awareness will allow you to make management decisions based on a more comprehensive understanding of what is affecting your turf sward. It may also help you to remain vigilant as varying weather patterns become more conducive for one or two of the underlying pathogens present in your sample.


Q: Why did I pay $135.00 to find out that I did not have a disease?

A: In our opinion, this is money well spent. Finding out your symptoms are not disease-related can save money in labour and product applications. It can often be troubling to discover that your biggest problem is not a disease, but rather the conducive environmental conditions of the location (ie. thatch issues, lack of sunlight or airflow, etc...) or in some cases a string of poor management decisions. We receive many samples each year that confirm abiotic stress rather than the presence of pathogens. Most often this is a result of over-management (cutting too low, overwatering, improper fertility, poor cultural practices, etc...) or challenging weather conditions. Consider the results from the diagnostic clinic a helpful guide for you and your team to focus your efforts in areas that are directly related to the confirmed problem - rather than throwing darts (very expensive darts) at a dartboard and hoping that one of these will solve your problem.


Q: When should I submit a sample for a nematode extraction?

A: Although nematodes are not quite as common in our climate as they are in the Southern US, reports of nematode issues in Canada are on the rise. We recommend submitting one or two samples from your property every year in order to develop what we call a baseline. This baseline will help you to understand how populations fluctuate from year to year, as well as helping you to understand what the population thresholds are on those sites. Similar to cholesterol levels, nematode population thresholds vary from property to property due to environmental conditions and various other factors such as traffic, soil, host species, etc... The more information you continue to collect on your nematode populations, the more prepared you will be if a problem was to occur. For more information, check out our blog post on plant-parasitic nematodes in cool-season climates.


Q: I submitted a sample 10 days ago but have not been billed yet - What is the delay?

A: We process our billing on a bi-monthly basis. The most you should ever wait before being charged and receiving your receipt via email is 15–20 days from the date we receive the sample. If you wish to expedite this process, please make a note on the form and we will do our best to process your charges ASAP.