Biotic Disorders

1
Biotic Disorders

• Read Chapter 10
• At the end of this section students should be
  able to
• 1) List and describe the seven major types of
  disease causing organisms
• 2) Know what the most important disease causing
  agent is in North America
• 3) Understand and list the classification scheme
  for fungi, phyla, their characteristics and the
  types of diseases they cause
• 4) Understand how fungi are spread and how the
  life cycles influence which part of the fungus is
  most important

2
Biotic Disorders

• 5) Know and list the strategies for fungal
  survival in the forest
• 6) Understand the close association between fungi
  and host plant in native diseases
• 7) Describe how and why introduced diseases are
  so effective at killing trees
• 8) Describe the importance of parasitic plants in
  the western United States

3
Biotic Disorders

• Plant Pathology - Pathogens, Parasites,
  Saprophytes, Symbiosis
• Pathogen
• Parasite
• Saprophyte
• Symbiosis
• Obligate

4
Biotic Disorders

• Plant Pathology - Pathogens, Parasites,
  Saprophytes, Symbiosis
• Facultative
• Obligate parasite
• Facultative parasite
• Obligate saprophyte
• Facultative saprophytes

5

• Disease Triangle Tetrahedron

Host
Time
Pathogen
Environment
6

• Disease Square

7
Biotic Disorders

• Signs and Symptoms of Disease
• Signs
• Symptoms

8
Biotic Disorders

• Symptoms of Disease
• Necrosis
• Decay
• Cankers
• Leaf spots
• Wilts

9
Biotic Disorders

• Symptoms of Disease
• Blights
• Hypertrophy
• Atrophy
• Physiology

10
(No Transcript)
11
Kochs Postulates

• Robert Koch 1843-1910
• Proved Bacillus anthrax was responsible for
  disease in animals and humans
• Noble Prize Winner 1905

12
Kochs Postulates

• Proof of Pathogenicity
• The pathogen must be associated with the disease
  in all the symptomatic plants examined.
• The pathogen must be isolated and grown in pure
  culture on nutrient media and its characteristics
  described.
• 3) The pathogen in pure culture must be
  inoculated into healthy plants of the same
  species and produce the same symptoms in the
  diseased plants in No. 1
• 4) The pathogen must be re-isolated from
  inoculated plants and grown in pure culture again
  and its characteristics must be like those
  described in No. 2

13
Biotic Disorders

• Types of biotic agents
• Fungi

14
Fungi

• Eukaroytic organisms
• Non-chlorophyll
• Vegetative growth is through mycelium Singular
  mycelia
• Single thread Hypha, plural (Hyphae)
• Propagate via spores

15
(No Transcript)
16
(No Transcript)
17
Classification of Fungi

• Zygomycota
• Oomycota
• Ascomycota
• Basidiomycota
• Deuteromycota

18
Oomycota

• Water molds
• Sexual reproduction Oospores
• Asexual reproduction Zoospores
• Example Littleleaf disease

19
(No Transcript)
20
(No Transcript)
21
Ascomycota Cup Fungi

• Sexual reproduction Ascospores are produced in
  a sac-like structure called an Ascus (Always 8
  Ascospores / Ascus)
• Apothecia open
• Perithecia closed and flask shaped
• Cleistothecia closed and ornamented
• Hysterthecia closed and elongated
• Asexual reproduction Conidia on a conidiphore
• Synnemata (flask shaped long)
• Pycnidia (flask shaped short)
• Spordochia (cushion or padded)

22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
Basdiomycota Gilled fungi

• Sexual reproduction Basidiospores are produced
  on a club-like structure called a Basidium
• Always 4 spores/basidia
• Asexual reproduction Conidia on a conidiphore
• Synnemata (flask shaped long)
• Pycnidia (flask shaped short)
• Spordochia (cushion or padded)

32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
Deuteromycota

• Sexual reproduction No known sexual state
  Fungi Imperfecti
• Asexual reproduction Conidia on a conidiophore
• Synnemata (flask shaped long)
• Pycnidia (flask shaped short)
• Spordochia (cushion or padded)

39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
Bacteria

• Single-celled, prokaryotic organisms
• Spread via
• wind, rain,
• insects,
• humans

44
(No Transcript)
45
(No Transcript)
46
Virus

• Protein encapsulated DNA or RNA
• Usually vectored by insects
• Results in yellowing, chlorosis, wilting,
  distortion of infected plant

47
(No Transcript)
48
Phytoplasmas

• Neither bacteria or virus, naked protoplasts with
  a membrane wall
• Vectored by insects
• Results in yellowing, chlorosis, wilting,
  distortion of infected plant

49
(No Transcript)
50
Parasitic Plants

• Obligate plants that derive their nutrition from
  trees
• Leafy Mistletoe
• Dwarf Mistletoe
• Dodder

51
(No Transcript)
52
(No Transcript)
53
(No Transcript)
54
Nematodes

• Non-segmented microscopic worms
• Live in soil
• Feed on root systems
• Vector virus bacteria
• Vectored by insects
• Pinewood Nematode

55
(No Transcript)
56
Questions to answer

• 1) Why are fungi the most important disease
  causing organisms of the seven types of organisms
  that cause disease?
• 2) In western North America what two types of
  disease causing organisms are responsible for the
  majority of forest diseases
• 3) Describe the features of fungi and how they
  grow and reproduce
• 4) Describe the difference between true mistletoe
  and dwarf mistletoes.
• 5) Describe the features of bacteria and how they
  grow and reproduce.
• 6) What are viruses and viroids? Describe how
  they disperse and the typical symptoms of virus
  disease in plants.

57

• 7) What is a nematode? What special feature
  makes this organism a plant pathogen?
• 8) Describe how you would tell fungi in the
  Ascomycota, Basidiomycota, Oomycota, Zygomycota
  apart?
• 9) Where do the Deuteromycota fit in the
  classification scheme of fungi?
• 10) Define the terms Disease, Signs Symptoms.
• 11) What are the seven biological agents causing
  plant disease?
• 12)What are Kochs Postulates?
• 13) Describe the disease triangle, the disease
  square and the disease tetrahedron and how they
  can be used to predict disease.