Class #1 for Plant Diagnostic Master Gardener specialist training

1. Master Gardener
Plant Diagnostic
Specialist Training
Part 1: Abiotic Issues

2. What is Diagnostics?
• Process used for the identification of problems
• Tools
–Plant sciences: horticulture, soil science,
plant pathology and entomology
–Art of investigation
Photo: Toronto Public Library, Special Collections (CC BY-SA 2.0)

3. Categories of Abiotic Problems
• Weather: temperature & rain/drought
• Irrigation issues
• Soil factors
• Fertility
• Chemical Injury
• Mechanical Injury
• Unusual growths/appearance

4. Be familiar with historic weather events
Source: https://weatherspark.com/history/30206/2015/Eugene-Oregon-United-States

5. Winter Injury
PNW Disease
Management Handbook
->Pathogen Articles
->Nonpathogenic Phenomena
->Winter Injury of Landscape Plants
in the Pacific Northwest

6. Low & High Temperature Damage
• Some plants tolerate
lower/higher temps
• Acclimatization is
important
• Easily confused with
chemical damage or
root disease
• Knowing plant’s history
is important
Photo: http://www.burpee.com/images/product/prod001210/prod001210_lg.jpg

7. Moisture
extremes
• Short-term or
chronic effects
Megan Kennelly, Kansas State University

8. Chronic low moisture stress leading to scorch
Megan Kennelly, Kansas State University

9. Tip burn of needles
Jennifer Olson, Oklahoma State University

10. Excess moisture can lead to edema
www.ipm.iastate.edu https://www-s.aces.uiuc.edu/photolib/lib17//midsize/fruit_trees_-_poor_drainage.jpg
Geranium Camellia
Photo: M. Willliamson

11. Soil compaction
E.L. Butler, North Carolina State University

12. Photos: http://www.ipm.iastate.edu/ipm/icm/node/565
http://www.landscaperesource.com/images/articles/soil_compaction_001.jpg

13. Soil pH
• Some plants are very sensitive
– i.e. Blueberry & rhododendron prefer acid soil
• pH affects nutrient availability
• Need to solve the ‘real’ problem

14. Fertility
http://www.soils4teachers.org/files/images/s4t/reaction-curve.jpg

15. Nutrient Disorder Diagnosis
• Tricky to use symptoms alone
• Some problems you will see repeatedly
• Ask questions of the client:
– Fertilizer regime?
– Soil conditions?
– Watering regime?

16. Diagnosing nutrient disorders
• Symptoms
• Soil tests
• Foliar tissue analysis
• Greenhouse potted plants
– Pour through analysis
Photo: http://vegetablemdonline.ppath.cornell.edu/Images/Impt_Diseases/81_Pep_Bloss.jpg

17. Phytotoxicity-Herbicide injury
• Herbicides have different modes of action (MOA)
– can affect photosynthesis, root growth, shoot growth,
and/or other aspects of plant growth
• Contact
– Shoots/foliage
– Root contact
• Systemic
– Translocated damage (xylem and/or phloem)
Good reference: http://msue.anr.msu.edu/uploads/files/6-
23%20Nursery%20grower%20checklist%20TOM%20herbicide
%20injury.pdf

18. Symptoms of herbicide injuries
• Depends on the ‘mode of action’
• http://herbicidesymptoms.ipm.ucanr.edu/index.c
fm
• Can search by herbicide and see symptoms on
multiple species
List of home use herbicides:
• http://pnwhandbooks.org/weed/horticultural/ho
me-garden-and-landscape-management/weed-
treatments-and-available-products-home-lands

19. Clopyralid and other pesticides in compost
http://ohioline.osu.edu/aex-fact/0714.html

20. Photo: Neil Bell, OSU Extension
Effect of clopyralid carry-over in compost

21. Glyphosate injury on cucumber (left) and healthy (right)

22. Characteristic glyphosate injury to tomato

23. Grapes are especially sensitive to 2,4-D
http://www.ppdl.purdue.edu/PPDL/images/herbicide-grape1.jpg
http://www.ppdl.purdue.edu/PPDL/images/herbicide-grape3.jpg

25. Continuum of damage
https://www.youtube.com/watch?v=OXca8ksXDlI&list=PLrQLElJHkjuh65RjQZ8nWDBh0Da_MekB0&index=4

26. Insecticides & Fungicides
• Review label!
• High temperatures
don’t mix with:
– Horticulture oils & sulfur
http://vegetablemdonline.ppath.cornell.edu/Images/Tomato/Tom_Malathion/67_03.jpg
http://extension.umd.edu/sites/default/files/_images/programs/hgic/Trees_Shrubs/EnvironmentalProblems/phyto_l2.JPG

27. Unusual growths or appearance
• Chimeras
• Burls
• Fasciation

29. Chimeras
Photo Source: https://ask.extension.org/uploads/question/images/attachments/000/012/285/Chimera_016_original.JPG?1365028081

30. Fasciation

31. Handling a frustrating case
• Step back from the sample and look at the big picture
• Request more information:
– A fresh sample
– A bigger sample
– Photos
• More than one problem may be involved
• Symptoms can be affected by:
– Environment
– Plant genetics
– Physiology
– The pathogen or degree of abiotic stress
Definitive diagnosis is not always possible