Slide 1

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 2

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 3

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 4

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 5

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 6

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 7

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 8

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 9

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 10

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 11

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 12

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 13

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 14

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 15

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 16

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 17

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 18

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 19

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 20

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 21

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 22

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 23

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 24

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 25

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 26

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 27

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 28

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 29

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 30

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 31

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 32

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 33

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)


Slide 34

Plant Diseases and Insect Pests
• Disease - any kind of injurious abnormality
– Physiological (environment)
– Other living organisms (pathogens)

• Pathogen - biological agent that causes the injury
–
–
–
–
–
–

Insects
Bacteria
Fungi
Viruses
Nematodes
Miscellaneous

Plant Diseases and Insect Pests
• Parasite - an organism that derives
nourishment from another living organism
• Host - an organism that provides nourishment
to another
• Obligate parasite - organism that can only
survive on the living host
• Host range - list of several different plants that
some parasites can feed off of

Plant Diseases and Insect Pests
• Bacteria - one-celled organisms that enter
through wounds and cause rot
• Fungi - multi-celled organisms that either
are saprophytes or parasites. Ex: molds,
mildew. Cause decay of plants

Bacterial rot/wilt

Fireblight on an apple

Bacterial disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves
evaporates by evening
• Antibiotics now exist for injecting into trees but
treatment is costly and the effects temporary.
There are no antibiotic spray treatments.

Fungal rots

Fungus on foliage

Fungal disease control?
• Start with clean pots & potting media & tools
• Start with clean seed or healthy transplants
• Use drip irrigation or water in the morning so the
extra water on the surface of the leaves evaporates
by evening
• Fungicides do exist. They can be used as a liquid
drench, spray or powder.

Captan & Thiram =
synthetic fungicides

Plant Diseases and Insect Pests
• Viruses - infectious particles made-up of
nucleic acids (typically RNA in plants) with a
protein coat. In the plant cell, the protein coat
comes off and the RNA uses the plant cell to
reproduce itself. These are obligate parasites.

Virus
Tobacco Mosaic Virus

No control methods!

Plant Diseases and Insect Pests
• Nematodes - unsegmented worms that
feed on roots and create wounds for
bacteria and fungi to enter

Nematode
damage
on tomato

Nematode damage on tomato

Nematode damage on carrot

Foliar nematodes
Hosta

Zinnia

How Plants are Damaged
• Damage by:
– Direct feeding
– Secretion of toxic substances
– Secondary organism enters the wound

• Symptom - plant’s response to attack (wilt)

• Sign - structures produced by the attacking
organism (webs, tunnels, etc.)

Symptom = wilt

Webbing = sign

Spread of Insects and Disease
• Diseases and insects are spread to plants by:
–
–
–
–
–

Water
Wind
Insects
Animals (including people) Ex: TMV
Machinery

• Plants are more susceptible to disease and
insect attack when they are stressed (water
or temperature)