The TPDDL can be contacted through email at plantclinic@tamu.edu or by phone (979) 321-5390.

The TPDDL is open Monday–Friday, 8:00 am – 5:00 pm, closed 12:00 pm – 1:00 pm.
Walk-in hours: Monday–Friday, 9:00 am – 4:00 pm, closed 12:00 pm – 1:00 pm.
The TPDDL is located at 1500 Research Parkway, Suite 130A, College Station, TX 77845. 

Dead plants may be overrun with saprophytes or secondary pathogens, making diagnosis difficult and leading to inaccurate results. Accurate disease identification, diagnosis, and management recommendations are dependent upon appropriate specimens and thorough background information. A good sample is taken from symptomatic material or the transition zone between healthy and declining material.

For specific tests that do not have a specified form, please use FORM D1178 – General Diagnostic Service Form and note the requested test in the Comment section.  Specific requested testing may incur additional charges. Please contact the TPDDL at plantclinic@tamu.edu if there is a need for specific testing of plant material for plant disease problems. 

The Texas Plant Disease Diagnostic Laboratory (TPDDL) is a service to the people of Texas by the Department of Plant Pathology and Microbiology at Texas A&M University in conjunction with the Texas AgriLife Extension Service.

The TPDDL can assist with any type of  plant disease problem. Field crops, trees, turfgrass, vegetables, fruits, flowers, shrubs, houseplants, or any other type of plant are welcome. Lab tests are available for the detection of most plant pathogens. We can only test soil for nematode detection. For testing of most diseases of Upper Plains field crops, please contact the THPPDDL. 

* For palm phytoplasma detection, please see the following document for sampling guidance: Sampling Guide for Palm Phytoplasma 

For nematode detection assay, see form D-827: https://plantclinic.tamu.edu/forms/d827/   

For commercial grape growers, see form D-1004: https://plantclinic.tamu.edu/forms/d1004/   

Billing Options:

• Complete a Form AG-257 to be billed after services have been completed. 
• • Department Contact: Courtney Overby
  • Email: courtney.overby@ag.tamu.edu
  • This form only needs to be completed once. If you’ve previously used AgriLife Extension services, you may already have a customer number—please include it on your TPDDL form when submitting samples.
    • Note: We cannot begin processing your sample without a customer number.

• If you are a homeowner or prefer not to provide identity information (e.g., SSN):
  • You may pre-pay by check instead of submitting Form AG-257.
  • Make checks payable to Texas AgriLife Extension Service.
  • The check must be made for the exact amount needed (e.g., $35 routine diagnostic fee, $55 routine + serological testing, etc.).
  • Use blue or black ink only.
  • Include the check and all required forms in the box with your sample.
  • You do not need to complete Form AG-257.
  • You will not be billed after your report is sent.
  • We will only perform the specific service(s) paid for—no additional confirmatory diagnostics will be conducted.

Please visit our Fees tab for more details about billing and cost: https://plantclinic.tamu.edu/fees/

Turnaround time is dependent on the specimen load received at the TPDDL. At peak time (spring through fall), routine diagnoses are usually finished in 11-21 days, depending on the test needed for the diagnosis. Specimens requiring extensive testing require more time. For example, oak wilt testing takes a minimum of 21 days. Diagnostic results are routinely emailed to the client, but results can also be mailed. 

Please get in touch with 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 the sample(s). 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. Please make sure to check your junk mailbox.  

Yes, you can view them at the links below:

• What can be sent to the clinic? 
• Packaging samples 
• Oak Wilt Sampling 
• Grass Sampling 

We also have a YouTube channel https://www.youtube.com/user/PlantDiseaseClinic

• Take a sample from the area where symptoms progress/transition and send it in with our general disease diagnosis form (D1178). 
• We care more about the plant material (leaves, stolons, runners, & roots) vs the soil or dead tissue. 
• You can take a sample when it is dry or wet but it should be placed in a Ziplock bag to ensure that the sample is not soaked or compromised by an extensive amount of moisture. 
• Our fee for Turfgrass diagnostics is $35/sample. If you want a diagnostic report for different areas of your yard, each will incur another $35 charge, and we will note whatever reference you use on the report. Please put the check and form(s) in the box along with the sample. 
• Grass Sampling video 

The accuracy of the laboratory assay is contingent upon the quality of the specimen submitted. Tissue that is too small, of the wrong type, desiccated, necrotic, or dead may contain too little viable vascular tissue or be contaminated with pathogens that will interfere with the isolation of the oak wilt fungus. Tissues selected from parts of the tree without good foliar symptoms may not be infected or sufficiently infected to produce a positive assay result. The current turnaround time for Oak Wilt is a minimum of 3 weeks due to the amount of time the fungus needs to grow on specialized media.

OAK WILT or DED (Dutch Elm Disease) sampling:  

1. Collect branches 1 inch to 2 inches in diameter showing symptomatic leaves.  
2. When possible, enclose twigs with symptomatic leaves still attached in a separate plastic bag.  
3. Place the plastic bags in a Styrofoam ice chest with ice packs—DO NOT SEND ON DRY ICE OR WITH ICE IN PLASTIC BAGS.  
4. Ship samples by overnight delivery to help ensure an accurate diagnosis.   
5. Complete the Plant Disease Diagnostic Form (D-1178). We encourage you to include recent pesticide history (last 3 weeks) and any other pertinent information.  Please put the check and form(s) in the box and the sample.   
6. Ensure the identification on the form matches the labels on the sample bags.  
7. Keep the completed form in a separate plastic bag from the specimen. Limit 1 (one) sample per form. 
8. Package all specimens securely to prevent damage during transit. Cardboard boxes usually help prevent crushing. Add packing material such as newspaper to prevent specimen damage during shipment.   
9. Ship samples to the above address by overnight delivery or mail early in the week to ensure fast delivery. Plant samples often decompose if left over the weekend in a delivery warehouse. Same-day or next-day service is recommended.   
10. Obtain one of the submission forms (D1178) from our website, complete it, and send it in with your sample.

• Oak Wilt Sampling video 

Samples can be submitted via courier, mail (preferably no more than 3-day delivery), or walk-in.
Walk-in hours: Monday–Friday, 9:00 am – 4:00 pm, closed 12:00 pm – 1:00 pm.
The TPDDL is located at 1500 Research Parkway, Suite 130A, College Station, TX 77845. 

Dead plants may be overrun with saprophytes or secondary pathogens, making diagnosis difficult and leading to inaccurate results. Accurate disease identification, diagnosis, and management recommendations are dependent upon appropriate specimens and thorough background information. A good sample is taken from symptomatic material or the transition zone between healthy and declining material.