The Texas Plant Disease Diagnostic Lab

11/29/2023 UPDATE: We apologize for the inconvenience, we will not be accepting any Oak Wilt samples from November 30, 2023-January 2nd, 2024, due to the testing incubation period. We will begin accepting Oak Wilt samples again starting January 1st, 2024. Also, the last day we will be accepting all other samples for the holiday is December 19th since we will be closed December 22nd through January 1st.

11/14/2023 UPDATE: Phone support is limited as we process an influx of samples. Please leave a voicemail or send an email to and we will get back to you as soon as possible. Thank you for your patience!

Since September 2021, we have utilized the current billing system that requires  all new clients should fill out form AG-257 (link to form here).  This should only occur once to set up a customer no. with Texas A&M AgriLife Extension Service. If you have used other AgriLife Extension services, you may have completed this prior – please include your customer no. on the TPDDL form when submitting samples.  Completion of this form Ag-257 is required for us to extend our ability to process your sample with necessary procedures for confirmatory diagnosis.

We can no longer bill customers without completion of the AG-257 form. IF a check is sent with your sample, then you will not need to fill out the AG-247 form and will not be billed after your report has been sent. We CANNOT begin any work on your submitted sample until we have a customer number in our system.

If you are a homeowner and/or do not want to provide your identity information (SSN) on the Ag-257, you can send a check in with your sample (pre-pay).  Please note, that we are only able to conduct analysis on the specific paid service that is requested and will not be able to pursue further analysis if needed for confirmatory diagnosis.

Please contact us by email IF you have received an invoice but not the report OR have not heard anything 15 business days (3 weeks) after submission of sample. We have instituted an email receipt reply notification to inform the submitter when we receive their sample and to provide a sample reference number for future inquiries related to that sample.

Homeowners are encouraged to check with their local Texas A&M AgriLife Extension Service county office for local assistance first.

Thank you for your patience and your support of the Texas Plant Disease Diagnostic Labs.


About The Texas Plant Disease Diagnostic Laboratory

Located in College Station, The Texas Plant Disease Diagnostic Laboratory is a Texas A&M AgriLife Extension Service lab managed by the Department of Plant Pathology and Microbiology at Texas A&M University.
The Texas High Plains Plant Disease Diagnostic Laboratory  is located at the Texas A&M AgriLife Research & Extension Center in Amarillo. The THPPDDL specialized in disease diagnostics of small grains and row crops.

Our Mission

To provide accurate and timely plant disease diagnostic support to AgriLife Extension & Research personnel, Texas Department of Agriculture, the agriculture/green industry and the people of Texas to protect and secure our plant resources and to promote economic competitiveness.

Our History

The idea for a plant disease diagnostic service at Texas A&M University started in 1956, when Dr. Harlan Smith, the Extension plant pathologist, used it as a way to provide support to Extension personnel and growers/farmers.  In 1982, the Texas Plant Disease Diagnostic Laboratory (TPDDL) was formally established, with the appointment of Dr. Larry Barnes as its first director. In 2002, the TPDDL was called upon to be one of many universities and state labs around the country to participate in the National Plant Diagnostic Network (NPDN) and perspective region, the Southern Plant Diagnostic Network (SPDN).  This network seeks to support a (i) secure regional network for the detection and diagnosis of plant health problems, (ii) extend and support sound public policies, implement rapid and accurate diagnoses, and response strategies, and (iii) provide leadership and training. Currently, the clinic processes approximately 3000 samples annually and supports/manages different projects under the direction of Dr. Kevin Ong and Head Diagnostician, Hannah Ayala.

If you would like to help support efforts at the Texas Plant Disease Diagnostic Labs or any of the Texas Plant Clinics, please contact us.

For assistance with plant health issues, please contact your local Texas A&M AgriLife Extension county office.  If contacting us, please email to get a quicker response. Our email contact is .  Thank you for your patience.