Plant Pathogens

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Plant Pathogens
A
C
B
F
D
E
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Is this disease?
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Symptoms of Plant DiseaseLesions - leaf spots

• Chlorosis
• Lesions
• Necrosis

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Symptoms of Plant DiseaseBlight

• Chlorosis
• Lesions
• Necrosis

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Symptoms of Blight Extensive and Sudden
necrosis
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Symptoms of Plant DiseasesColor Changes-
Chlorosis
Normal
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Symptoms of Plant DiseaseColor changes -
anthocyanins

• Chlorosis
• Anthocyanins
• Blockage of phloem
• High concentration of sugars
• Sugars convert to anthocyanins
• What seasonal
• phenomenon will
• result a similar
• phenotype soon??

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Mosaic and Rugosity Symptoms
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Symptoms of Plant Disease Change in shape -
Rugosity
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Symptoms of Plant Disease

• Changes in Tissue Shape and Size
• Hypertrophy
• (Overdevelopment size development)
• Gall

Gall
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Nodules (left) caused by Rhizobium vs. Galls
(right) caused by a pathogen

• Nodules - Rhizobium

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Symptoms of Plant DiseaseNecrosis

• Lesions
• Cankers
• Concave lesion

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Symptoms of Plant DiseasesDisruption of
Reproduction
Fruit spots are small, tan later turn brown and
become spotted with fungal fruiting bodies.
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Symptoms of Plant Disease Disruption of
Reproduction - Floral parts are replaced by
vegetative structures
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Symptoms of Plant DiseaseWilt

• Low soil moisture
• Physical damage
• Toxin
• Stem boring insect
• Root rot
• Stem canker
• Pathogen of vascular system

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Symptoms of Plant DiseaseWilt

• Necrosis
• Lesion
• Cankers

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Hypotrophic SymptomStunting
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Symptoms of Plant DiseaseWilt
Wilt of foliage Due to root necrosis
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Primary and Secondary Symptoms

• Wilt

• Root rot (necrosis)

Pathogen absent in leaves
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Primary and SecondarySymptoms
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Symptoms and Microscopic SignVascular system
necrosis of root and wilt of foliage
Xylem vessels
Pathogen colonizing host vascular tissues
Dead and discolored tissues resulting from
infection
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Symptoms of Plant Disease

• Changes in Tissue Shape and Size
• Hypertrophy
• (Overdevelopment size development)
• Brooms

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Signs of Plant Disease

• Sign is any microscopic or macroscopic structure
  of the causal pathogen
• Stem rust pathogen of wheat masses of spores of
  pathogen

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Signs of Plant Disease

• White mycelium on surface of pumpkin is an
  oomycete that is casuing rot of host internal
  tissues
• Macroscopic signs
• Microscopic signs

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Signs of Plant Disease

• Or is white mycelium on surface of pumpkin a
  saprophyte living on dead tissue killed by
  another organism???