Clinic Overview

PDDC Brochure IconThe Plant Disease Diagnostics Clinic (PDDC) provides assistance in identifying plant diseases and provides educational information on plant diseases and their control.

Each year, the PDDC processes numerous (over 2000 in 2020) physical and digital photo samples of plants, providing diagnoses of the diseases affecting these plants.

The PDDC is part of the Plant Pathology Department in the University of Wisconsin-Madison and is housed on campus in the Russell Labs building.


The PDDC was founded by Sr. Mary Francis Heimann, OSB in 1973 to provide support for county UW-Extension agents throughout Wisconsin.  Today, the PDDC continues to provide support for the UW-Madison Division of Extension, and also provides diagnostic services directly to citizens of Wisconsin and beyond.  


Director Brian Hudelson

The Clinic is run by Brian Hudelson, Director of Diagnostic Services.

Brian is a Madison native and earned all three of his degrees here at UW-Madison.

He brings many years of experience to the table, and clients throughout the State turn to him for diagnosis and advice on plant disease topics.  A sought-after public speaker and instructor, Brian is known for his down-to-earth style, dry sense of humor, and ability to describe  complex scientific topics in relatable terms.

A dedicated teacher, Brian delights in finding innovative ways to engage learners and share his love for plant diseases.  Recent projects included:

You can learn more about Brian on the Staff page.

Visit our Talks for the General Public page to learn how to book Brian for your presentation, workshop or other outreach activity.


The Clinic’s services break down into two general areas – Diagnostic Services and Outreach/Education.

Diagnostic Services

Brian Hudelson at the Microscope

  • Identify plant diseases via physical samples and digital photos


Brian at Garden Expo

    • College for-credit courses – at least one undergraduate course in Plant Pathology per year
    • Continuing education – talks and workshops on plant diseases
    • Informational booths – ask the expert in person at events like Wisconsin Garden Expo and West Madison ARS Horticulture Day
    • Informational resources – training modules, podcasts, fact sheets
    • Radio and television – appearing as a guest on WI Public Radio, WI Public Television
    • Social media – Facebook or Twitter/X (@UWPDDC
    • Disease statistics – weekly report on plant diseases found in by Clinic (Wisconsin Disease Almanac)


  • Home gardeners
  • Master gardeners
  • Arborist/Landscape Professionals
  • Greenhouse Growers
  • Nursery Growers
  • Agricultural Crop Consultants
  • Students

Learn More

Click the links below to learn more about the Clinic.

Sample Collection and Submission

  • Learn how to collect, prepare, and submit digital photos and physical samples.

Diagnostic Services and Fees

  • Learn what services we provide, and what we charge for those services.


  • Read the bio of the Clinic’s Director, Brian Hudelson

Contact Us

  • Learn about our hours and how to reach us.
  • View directions and maps to the Clinic.


  • Read testimonials from happy PDDC customers.

Help Us Improve Our Services

  • Take our customer satisfaction survey.

Alphabetical Site Index

  • A list of all the pages on the site, in alphabetical order.  Note: the list does not include Fact Sheets and blog entries.