Basic Plant Pathology for Franklin County Master Gardener Volunteers. Nancy J. Taylor Plant Pathology Department Ohio State University

Transcription

1 Basic Plant Pathology for Franklin County Master Gardener Volunteers Nancy J. Taylor Plant Pathology Department Ohio State University

2 PuP_QbD14

3

4 Mildews

5 Mildews

6 Mildews Rots

7 Mildews Rots

8 Mildews Rots Rusts

9 Mildews Rots Rusts

10 Mildews Rots Diebacks Rusts

11 Just what is a plant disease?

12 Just what is a plant disease? A Plant Disease: Causes injury to plants Increases in severity and is progressive over time May be caused by a living or non-living agent

13 Major Causes of Plant Diseases Abiotic Non-living, or caused by a nonliving agent. Noninfectious, caused by an environmental factor Biotic Living, or caused by a living agent. Also infectious, caused by an agent which can spread from one plant to another

14 Biotic causes of plant diseases: Fungi Bacteria Viruses Nematodes Phytoplasmas, virions, others

15 Biotic causes of plant diseases: Fungi Bacteria Viruses Nematodes Phytoplasmas, virions, others

16 Fungal Plant Diseases Fungus or Fungi

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42 Fungi Mostly microscopic Most are multicellular Made up of filaments Cannot produce their own food Many form complex reproductive structures Most reproduce by producing spores Nonmotile Can actively penetrate plants

43 Fungi?

44 Biotic causes of plant diseases: Fungi Bacteria Viruses Nematodes Phytoplasmas, virions, others

45 Bacterial Plant Diseases

46

47

48

49

50

51

52

53

54

55 Bacteria Single celled Each is smaller than a fungal spore Most do have cell walls Do not form complex structures Some are slightly motile using flagella (tails) Cannot actively penetrate plants

56 Bacterial Diseases?

57 Biotic causes of plant diseases: Fungi Bacteria Viruses Nematodes Phytoplasmas, virions, others

58 Viral Plant Diseases Virus or Viruses

59

60 Brunt, A.A., Crabtree, K., Dallwitz, M.J., Gibbs, A.J., Watson, L. and Zurcher, E.J. (eds.) ( 1996 onwards). `Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 20th August 1996.'

61

62

63

64

65

66

67 Viruses Too small to see with microscope Cannot reproduce outside of living cells Most consist of nucleic acid (DNA) and a protein coat Most require an opening to infect Cannot move by themselves

68 Viral Diseases?

69 Nematode Plant Diseases Nematodes

70

71

72

73

74

75

76

77 Plant Parasitic Nematodes Nonsegmented roundworms Very small, some barely visible to naked eye Can be found everywhere Most are harmless, even beneficial Reproduce by laying eggs

78 Nematode Diseases?

79 What causes infectious plant diseases? Fungi Bacteria Viruses Nematodes Others Parasitic plants Bacteria without cell walls phytoplasmas, spiroplasmas Filamentous bacteria actinomycetes Viroids Straminophiles (water molds)

80

81 Disease Cycle

82 Disease Cycle The stages of development of the pathogen and its effect on the host plant.

83 Disease Cycle

84 Disease Cycle

85 Disease Cycle Inoculation: The pathogen comes into contact with the host or host organ Penetration: The initial invasion of the host by the pathogen Initial Establishment: The pathogen begins to obtain nutrients from the host Growth and Reproduction: Spread of the pathogen within the host Dissemination: Pathogen moves or is moved to another host or host organ Overwintering/Oversummering: Survival during adverse conditions

86 Disease Cycle

87 Disease Cycle

88 Disease Cycle Cherry Leaf Spot

89

90

91

92 New York State Agricultural Experiment Station for use of this figure. Taken from Tree Fruit Crops IPM Disease Identification Sheet No. 8.

93

94

95

96

97 Plant Diseases - Symptoms and Signs

98 Symptoms of plant disease The response or responses of a plant to an irritant, in this case a plant disease. How the plant responds to a pathogen The appearance of the diseased plant.

99 Signs of plant disease The visible presence of the pathogen in or on the plant. The parts or products of the pathogen which are found in or on the plant.

100 Which diagnosis is more definitive? Symptoms? Signs?

101 Leaf spot A dead area on a leaf. May be circular, angular or irregular.

102 Apple scab

103

104

105

106 Black spot Rose

107 Early Blight- Tomato

108 Tar Spot- Maple

109 Angular Leaf Spot- Cucurbit

110 Bacterial Leaf Spot- English Ivy

111 Leaf scorch or leaf tipburn Leaf death from the edge of the leaf inward. Usually in a uniform pattern on the leaf and may be uniform throughout the plant.

112 Scorch

113 Scorch

114 Scorch

115 Scorch

116 Powdery Mildew Whitish growth on the plant surface, usually on leaves but may be on stems.

117 Powdery Mildew- Cucurbit

118 Powdery Mildew- Crabapple

119 Powdery Mildew- Sycamore

120 Powdery Mildew

121 Powdery Mildew- Lilac

122 Leaf blister Portions of the leaf are raised (distorted).

123 Peach Leaf Curl

124 Scab Rough, crusty spot or area on the surface of the plant tissue.

125 Apple Scab

126 Apple Scab

127 Apple Scab

128 Apple Scab

129 Pyracantha Scab

130 Defoliation Loss of leaves. Leaf drop.

131 Sycamore Anthracnose

132 Chlorosis/Chlorotic Yellowing of normally green tissue

133 Pin Oak Chlorosis

134 Pin Oak Chlorotic

135 Dogwood Normal

136 Wilt Drooping of plants or plant parts, usually due to lack of water in the plant

137 Verticillium Wilt Tomato

138 Bacterial Wilt Cucumber

139 Root Knot Nematode

140 Verticillium Wilt Maple

141 Verticillium Wilt Maple

142 Blight Sudden death of leaves, flowers, or stems. Usually occurs throughout a group of similar plants.

143 Botrytis Blight Geranium

144 Botrytis Blight Geranium

145 Early Blight- Tomato

146 Fire Blight Apple

147 Pustule A raised, blisterlike area resulting from the growth of a pathogen beneath the surface

148 Fungal Pustule

149 Fungal Pustule Sphaeropsis

150 Fungal Pustule Rust

151 Rust Pustule Geranium

152 Rust Pustule Geranium

153 Rust Pustules Geranium

154 Canker A dead area or lesion on a stem, may be raised or sunken.

155 Canker

156 Nectria Canker Apple

157 Nectria Canker Apple Pustules

158 Early Blight Tomato

159 Fire Blight Apple

160 Gall Swollen or overgrown tissue on a plant.

161 Crown Gall Rose

162 Black Knot Plum

163 Root Knot Nematode Tomato

164 Root rot Death of roots. Softening, discoloration and/or disintegration of roots resulting from an infectious agent

165 Root Rot Rhododendron

166 Plant Diseases Symptoms=Plant s appearance Signs=Pathogen s appearance

167

168 DISEASE TRIANGLE

169 = HOST = Susceptible Plant

170 Virus Bacterium Nematode Fungus Pathogen Parasitic plants Abiotic factors Mollicutes Flagellate Protozoa

171 Favorable Environment

172 Environment Host Pathogen

173 Environment Host No Disease Pathogen

174 Environment Host ENPHYTIC DISEASE Pathogen

175 Environment Host Pathogen EPIPHYTOTIC DISEASE

176 Environment Host Pathogen Manage the ENVIRONMENT to reduce plant disease.

177 Environment Host Pathogen Manage the PATHOGEN to reduce plant disease.

178 Environment Host Pathogen Manage the HOST to reduce plant disease.

179 Environment Host Pathogen

180 Basic Plant Pathology for Ohio s Master Gardeners Understand the difference between abiotic and biotic diseases Recognize the diversity of plant pathogens Understand the disease cycle its impact on disease development and control Understand the disease triangle its effect on disease control Recognize some common symptoms of plant disease

181 Basic Plant Pathology for Ohio s Master Gardeners This presentation contains copyrighted images and may not be reproduced