An online series aimed at providing the tools needed to investigate threats to plant health.
Are you interested in improving your plant disease diagnostic skills? The Develop Your Diagnostic Skills (DYDS) webinar series is a unique training opportunity developed specifically for those that give advice, answer questions, and educate others on plant health and plant disease issues. Diagnosticians from Cornell University’s Plant Disease Diagnostic Clinic will provide 12-hours of comprehensive content in a 6-week course that will focus on recognition of important plant diseases and the pathogens that cause them, grouping diseases by symptom expression to discuss identification techniques and damage caused, and offering interactive learning exercises to practice and hone diagnostic skills.
Presenters: Karen Snover-Clift, Director & Molecular Diagnostician of the Plant Disease Diagnostic Clinic at Cornell University, and Sandra Jensen, Diagnostician of the Plant Disease Diagnostic Clinic at Cornell University
Dates/Times: Tuesdays, January 20, 27, February 3, 10, 17 & 24, 2026; 3-5pm EST
Fee: $300 per person; $250 for Cornell Cooperative Extension employees & volunteers. See group registration information (5 or more people) at the bottom of this page.
Participants must have access to Zoom to participate in real time. Lectures will be recorded and available to participants after live sessions.
Who Should Attend: extension educators, master gardeners, landscapers, landscape designers, arborists, foresters, IPM technicians, land managers, nursery growers and managers, horticulture professionals, and others interested in learning core plant diagnostics.
CEUs:
- DEC: Modules 1, 2, 4, 5, and 6 – 2 CEUs for each Module in Categories 1a, 2, 3a, 3c, 10, 21, 22, 23, 24, 25; Module 3: 2 CEUs in Categories 1a, 2, 3a, 10, 21, 22, 23, 25.
- ISA: 2 CEUs for each session.
- CNLP: 2 CEUs for each session.
- Attendees seeking CEUs will be required to sign-in 15 minutes before each presentation (2:45pm EST) using the Chat feature, noting full name, license number and email. Attendees must remain for the duration of the class, answer all quiz questions and sign out at the end of each session to earn credits. Attendees must send photos or scans of their ID cards by 1/16/2026 to sr369@cornell.edu
Full Course Description:
When plants look sick and die, their curators often seek answers. Determining the cause of plant health issues requires the development of key diagnostic skills such as observing site conditions and damage patterns, crafting key questions specific to the individual situation, acquiring and maintaining a knowledge base of commonly found plant diseases, keeping up-to-date on threatening or new-to-our-area plant diseases, and selecting diagnostic techniques that will identify the primary cause of the problem. When providing a diagnostic response, this skill set needs to include the ability to customize the most appropriate management options and emphasize key facts that will guide those seeking help. The Develop Your Diagnostic Skills (DYDS) webinar series will review threats to plant health using a wide variety of host plant types including ornamentals, turf, field crops, fruits, and vegetables and review common plant diseases and threats for which we need to be on the lookout.
This comprehensive webinar series will include the following modules, each featuring numerous examples to reinforce the topic and learning exercises to strengthen diagnostic skills.
Module 1: DYDS – Threats to Plant Health (Pathogens, Pests and Abiotic Issues)
The first session of the Develop Your Diagnostic Skills webinar series will cover the five (5) groups of microorganisms that cause plant disease and introduce abiotic causes of plant damage. The speaker will review plant pathogenic fungi, bacteria, nematodes, viruses and phytoplasmas; describe common characteristic symptoms and signs for each group; and provide several examples of infected plants displaying characteristics symptoms. The speakers will convey how a diagnostician uses the key characteristics to compare each pathogen group to the others and to abiotic damage. The speakers will use a wide variety of plant species to demonstrate how observing patterns of damage in a community of plants, on an individual plant and on individual plant parts and observing the progression of damage over time, can lead to the determination of either an abiotic factor or biotic organism cause. The session will conclude with reviewing key terms used in the discussion and supplying a crossword activity as a homework assignment.
Module 2: DYDS – Leaf Spots and Tatters and Blights…Oh My!
The second session of the Develop Your Diagnostic Skills webinar series will cover the plant diseases that fall into the category of leaf diseases, including leaf spots and blights. Being the largest group of plant disease types, the speakers will highlight diseases caused by all five groups of organisms: fungi, bacteria, viruses, nematodes and phytoplasmas. The speakers will review the most common and most threatening leaf diseases, link them to the plant disease causing organism(s), and highlight contrasting symptoms caused by abiotic factors. They will review the management and discuss the importance of selecting the most appropriate management strategies such as exclusion, eradication, protection, resistance, and therapy, based on site characteristics, type of host plant, and planting style. The session will conclude with a “What would you do?” exercise. Participants need to consider a scenario and answer relevant questions based on what they have learned.
Module 3: DYDS – The Wilts and the Wounded (Vascular Wilts and Cankers).
The third session of the Develop Your Diagnostic Skills webinar series will cover plant diseases in the categories of vascular wilts and cankers. The speakers will highlight diseases caused by highly significant plant disease causing organisms to include historically important diseases, such as late blight and Dutch elm disease, and more recent arrivals, such as corn stunt, plum pox, oak wilt and laurel wilt. The speakers will review key characteristics that will lead plant disease investigators to the most likely cause of the damage and highlight contrasting symptoms caused by abiotic factors. They will review management options and discuss the importance of selecting the most appropriate management strategy based on site characteristics, type of host plant, and planting style. The presentation will conclude with a review of a factsheet and an exercise to find key pieces of information that will aid in the development of key management steps for the infected plants of the scenario.
Module 4: DYDS – Rots, Galls and Diebacks with a Vengeance
The fourth session of the Develop Your Diagnostic Skills webinar series will cover the plant diseases that fall into the category of root and crown rots, galls, and diebacks on a wide variety of plant hosts caused by plant pathogens and abiotic factors. The speakers will review common but highly damaging diseases; such as Armillaria wood, root and crown rot; crown gall; nematode root galls; and an array of dieback diseases; will link key symptoms to the plant pathogens causing the damage and will highlight contrasting symptoms caused by abiotic factors. They will review the management and discuss the importance of selecting the most appropriate management strategies based on site characteristics, type of host plant, and planting style. The session will conclude with a “What would you do?” scenario exercise. Participants use their acquired diagnostic skills to answer relevant questions.
Module 5: DYDS – People and Plant Diseases: The Good, the Bad and the Helpful
The fifth session of the Develop Your Diagnostic Skills webinar series will cover how people may contribute to plant disease issues and what they can do to lower the risk of significant damage. The speakers will discuss monocultures, introducing non-native plants, using genetically uniform seed, water management, improper use of fertilizers and pesticides, and repeated planting of economically valuable crops. They will discuss how pathogens survive in the absence of a host plant, using survival structures, other plants such as weeds, and how they survive in seed, in vectors, in host debris, and in soil. Presenting this information will include highlighting useful steps that can be taken to lower the risk of plant disease occurrence and early identification of infections. The session will conclude with a “What could go wrong?” exercise where participants pick a host plant and research the possible plant diseases that could infect their chosen host.
Module 6: DYDS – Case by Case Whodunits
The sixth session of the Develop Your Diagnostic Skills webinar series will cover the diagnostic process by using examples taken from ~30 years of Plant Disease Diagnostic Clinic submissions. The speakers will review the steps of the diagnostic process, how to submit a sample, initial analysis to determine best next steps, selection of appropriate test methods, interpretation of test results, and developing the diagnostic response appropriate for the submitter. Several cases will be presented to provide opportunities to use their diagnostic skill set in various situations. Examples may include samples that are submitted at a time of year when the pathogen’s presence is difficult to find, when the appropriate plant parts are not submitted, when abiotic issues make plants more susceptible to opportunistic plant pathogens, and when numerous pathogens are present on one sample. The session will conclude with a “What would you do?” exercise. Participants will develop a diagnostic report providing key details the sample submitter needs to know to respond to their case, primarily providing management actions that will lessen reoccurrence and reduce spread.
GROUP RATE: submit 5 registrations at the regular rate ($300/person or $250/person for CCE staff/volunteers) and have access for other staff and/or volunteers to attend the webinars. To register your group contact Shari Romar at sr369@cornell.edu.
PLEASE NOTE the following:
- Attendees seeking credits must attend as an individual on a computer and cannot attend as part of a larger group setting. This is a requirement of the credit organizations.
- We are extending this group rate in good faith. If your group participates, please only include your immediate staff and/or volunteers.