Enhancing Plant Disease Diagnostic Skills... …to build a stronger partnership between Specialists, Agents and Growers P. Bachi and J. Beale, Diagnosticians J. Hartman, D. Hershman, W. Nesmith, and P. Vincelli, Extension Plant Pathologists Plant Pathology Department, University of Kentucky

Diagnosis is... Hypothesis-testing

Think of each diagnosis as a research project. 1.Examine samples and gather information 2.Formulate hypothesis 3.Test hypothesis 4.Accept or reject hypothesis based on results

Examine samples and gather information to formulate hypothesis.

Test hypothesis.

Diagnostic Rule: “Do make the diagnosis fit the symptoms (evidence); Don’t make the symptoms (evidence) fit the diagnosis.”

Diagnostic Rule: “Correlation is not causation.” or “Just because it’s there now, doesn’t mean it caused the problem.”

G. Kemmitt R.E.Stall W. E. Fry

Diagnostic Rule: “Know when you know; know when you don’t know.” – Bill Nesmith know when you don’t know.” – Bill Nesmith

How can we work better as partners? Specialists and Diagnosticians - Stay focused on the science - Timely diagnosis and reporting - New initiatives for greater efficiency - Education vs. service?

How can we work better as partners? County Extension Agents - Key in Detection - “Eyes and ears” - Critical link between local community & lab/specialists - Rapport with public

Diagnostic Initiatives for 2003 and Beyond - Real-time PCR - Digital Consulting System

Polymerase Chain Reaction (PCR) The most important technique in molecular biologyThe most important technique in molecular biology Amplifies specific DNA sequence exponentially, by chain reactionAmplifies specific DNA sequence exponentially, by chain reaction

Real Time PCR Learn results of PCR test in real timeLearn results of PCR test in real time As a diagnostic technology, it is remarkably:As a diagnostic technology, it is remarkably: – Rapid – Sensitive – Specific

Smart Cycler® Real Time PCR Machine

Anticipated Diagnostic Applications in the near term Pierce’s disease of grapePierce’s disease of grape Bacterial spot of pepper and tomatoBacterial spot of pepper and tomato –Detection of pathogen species and race Bacterial speck of tomatoBacterial speck of tomato Bacterial wilt of tomato and tobaccoBacterial wilt of tomato and tobacco Bacterial canker of tomatoBacterial canker of tomato

Anticipated Diagnostic Applications in the near term (cont’d) Bacterial wilt of cucurbitsBacterial wilt of cucurbits Yellow vine decline of cucurbitsYellow vine decline of cucurbits Verticillium wilt of woody ornamentalsVerticillium wilt of woody ornamentals Spring dead spot of bermudagrassSpring dead spot of bermudagrass