20 Questions of Plant Diagnosis

Diagnosing plant problems is often a complex, multifaceted process that requires observation, investigation, and integration of site-specific knowledge. A structured diagnostic approach reduces guesswork and ensures more accurate conclusions. Below are 20 essential questions that every plant healthcare professional should consider when diagnosing plant issues.

1. What is the plant?

Correct plant identification is foundational. Know the species and cultivar, as this informs expectations about growth, susceptibility, and environmental needs.

2. What is normal for this plant?

Understand the typical appearance, seasonal cycles, and behaviors (e.g., leaf drop, color changes) so that abnormalities stand out clearly.

3. What are the symptoms?

Describe precisely what you see: leaf spots, wilting, chlorosis, dieback, etc. Be objective and avoid assumptions at this stage.

4. What is the distribution of symptoms on the plant?

Localized symptoms may suggest mechanical injury or pests; systemic symptoms could indicate vascular disease or root issues.

5. What is the pattern of damage in the planting?

Are multiple plants affected? Are symptoms random, uniform, or edge-biased? This helps distinguish between biotic and abiotic issues.

6. What is the history of the problem?

When were symptoms first observed? Have they progressed? This helps determine if the issue is acute, chronic, or recurring.

7. What recent changes have occurred on the site?

Construction, pesticide applications, soil disturbance, or irrigation adjustments can all stress plants or introduce problems.

8. What cultural practices are in place?

Consider mowing, pruning, irrigation, mulching, and fertilization—any of these, if misapplied, can stress or injure plants.

9. What is the soil condition?

Check pH, drainage, compaction, and organic matter. Poor soil health can limit root function and mimic disease.

10. What are the environmental conditions?

Light, temperature, wind exposure, humidity, and microclimates can significantly influence plant health and disease development.

11. Are pests present?

Look for insects, mites, or other arthropods. Determine if they are primary pests or secondary invaders on stressed tissue.

12. Are pathogens present?

Signs such as fungal fruiting bodies, bacterial ooze, or nematode cysts may be clues. Lab testing may be required for confirmation.

13. Are there signs as well as symptoms?

Signs (the actual pathogen, insect, or byproduct) help confirm the cause, while symptoms are the plant’s response.

14. Could abiotic factors be involved?

Drought, salt injury, herbicide drift, and nutrient imbalances often mimic biotic problems and are frequently overlooked.

15. Have samples been collected for testing?

If uncertain, send samples to a diagnostic lab. Follow proper protocols for collecting and submitting samples.

16. What are the weather patterns leading up to the issue?

Excessive rain, drought, or unseasonable temperature swings can trigger stress responses or disease outbreaks.

17. Are multiple problems present?

Often, more than one factor is at play—a stressed plant from poor drainage may become infested by opportunistic pests.

18. Have you consulted references or experts?

Cross-check your findings with literature, colleagues, or university extensions to validate your diagnosis.

19. What is the recommended management strategy?

Based on the diagnosis, determine whether treatment is cultural, chemical, mechanical, or a combination.

20. How will you monitor and follow up?

Diagnosis is just the beginning. Document findings, apply treatments, and reassess the plant’s response over time.

Conclusion:
The “20 Questions” approach builds a systematic framework for diagnostics. While not every question will apply in every case, collectively they guide practitioners toward a thorough, professional, and science-based diagnosis. The result is more accurate solutions and greater client confidence in your services.