Principles%20of%20Plant%20Disease%20Diagnosis

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Principles of Plant Disease Diagnosis

• Chuan Hong
• Virginia Tech

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Outline

• Significance of disease diagnoses
• Do-it-yourself requirements
• Basic procedures
• Basic tools
• Where to get help

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Starving Irish people emigrating to N. America
following potato famine caused by
Phytophthora infestans in 1840s
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Stand of young, pole-sized chestnut trees
devastated by Cryphonectria parasitica in West
Virginia during the chestnut blight epidemic of
1904-1944
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Bacillus anthracis
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Outline

• Significance of disease diagnoses
• Do-it-yourself requirements
• Basic procedures
• Basic tools
• Where to get help

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Do-it-yourself Requirements

• Types of plant diseases
• Significance of individual diseases
• Your goal of disease diagnosis

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Type of Plant Diseases I

• Blights
• Leaf spots
• Mildews
• Root rots
• Rusts
• Wilts

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Wilt
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Type of Plant Diseases II

• Infectious diseases
• Non-infectious diseases

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Type of Plant Diseases III

• Non-infectious diseases
• Weather related (frost, hail,)
• Chemical injuries (fertilizers, herbicides,
  fungicides, )
• Water related (to wet or dry)
• Excess or deficiency of micronutrients
• ..

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Type of Plant Diseases IV

• Infectious diseases
• Bacterial diseases (1600/100)
• Fungal diseases (1.5 m/10 000)
• Nematode diseases
• Virus diseases

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Morphology and Multiplication of Some of Groups
of Plant Pathogens
Fungi Bacteria Mollicutes Parasitic higher
plants Viruses Nematodes
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The Shapes and Sizes of Certain Plant Pathogens
in Relation to a Plant Cell
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Scheme of Disease Diagnosis
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Do-it-yourself Requirements

• Types of plant diseases
• Significance of individual diseases
• Your goal of disease diagnosis

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Source Plant Disease Clinic Annual Report
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Source Plant Disease Clinic Annual Report
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Source Plant Disease Clinic Annual Report
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Do-it-yourself Requirements

• Types of plant diseases
• Significance of individual diseases
• Your goal of disease diagnosis

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Objective of Disease Diagnosis

• Become a plant pathologist ?
• Become a practitioner
• Help making recommendations on disease control in
  home gardens, specifically on fungicide/biocide
  selection

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Limited Biocide Options

• Ferti-lome
• Halt systemic
• Monterey
• Aliette
• Ortho
• Daconil