Diseases of various Plants
Transcript of Diseases of various Plants
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PLANT DISEASE
OrPlants Do Get Sick
John F. Baniecki, Ph.D.
Extension Specialist and Professor
West Virginia University
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WHAT IS A PLANT DISEASE?
A plant disease may be defined asany disturbance that prevents the
normal development of a plant and
reduces its economic or aestheticvalue.
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ASSOCIATED WITH A DISEASE ARE:
SYMPTOMS
SIGNS
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A
SYMPTOM
The visible response of a plant to acausal agent over time.
May be caused by:living agents (Biotic)
non-living agents (Abiotic)
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PLANT DISEASE SYMPTOMS
Produced by non-living agents(Abiotic)
Environmental
Chemical
Nutritional
Cultural
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PLANT DISEASE SYMPTOMS
EnvironmentalCold
Heat or DroughtLightning
Wetness
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PLANT DISEASE SYMPTOMS
Environmental
Cold------------Brrrrrrrrrr!
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PLANT DISEASE SYMPTOMSEnvironmental
Heat or Drought
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PLANT DISEASE SYMPTOMS
Environmental
Lightning Damage
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PLANT DISEASE SYMPTOMS
Environmental
Wetness Results: Root Rot
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PLANT DISEASE SYMPTOMS
Chemical
Salt Fertilizer Pesticide
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PLANT DISEASE SYMPTOMS
Nutritional
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PLANT DISEASE SYMPTOMS
CulturalTree Girdling
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PLANT DISEASE SYMPTOMS
CulturalOverwatering
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PLANT DISEASE SYMPTOMS
Produced by Living Agents (Biotic)
Fungi
BacteriaViruses, Viroids, Mycoplasmas
SpiroplasmsNematodes
Parasitic Vascular Plants
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PLANT DISEASE SYMPTOMS
Fungi
Lower forms of plant life
Microscopic thread-like growthLack chlorophyll
Attack higher forms of plant lifeSpread by wind, rain, insects
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PLANT DISEASE SYMPTOMS
Fungi
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PLANT DISEASE SYMPTOMS
Fungi cause:
Leaf spots or BlotchesBlight
Cankers
Root rot
Wilt and/or reduced growth, death
Trunk rot
Abnormal growth or galls
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PLANT DISEASE SYMPTOMS
BacteriaSingle celled organisms
Enter the plant through naturalopenings or plant injuries
Spread by wind, rain, insects
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PLANT DISEASE SYMPTOMS
Bacteria Streaming from a plant
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PLANT DISEASE SYMPTOMS
Bacteria cause:
Leaf spots or BlotchesBlight
Cankers
Root rot
Wilt and/or reduced growth, death
Abnormal growth or galls
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PLANT DISEASE SYMPTOMS
VirusesSubmicroscopic, replicate inside
living cells
Composed of a piece of genetic
material (either RNA or DNA)
surrounded by a protein coatTakes over the plant cell metabolism
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PLANT DISEASE SYMPTOMS
VirusesGain entry to cells through a wound or
during insect feeding
Spread by man and insects
Occurs in weeds and other plants
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PLANT DISEASE SYMPTOMS
VirusesCan be maintained in a population of
plants or
transferred from plant to plant by:
vegetative propagation
grafting
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PLANT DISEASE SYMPTOMS
VirusesCan also be maintained or transferred by:
dodder, a parasitic plant
mechanically in sap on hands, tools,
ropes, etc.
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PLANT DISEASE SYMPTOMS
Viruses
Can also be maintained or transferred
by:
feeding by nematodes, mites, aphids,
leaf hoppers, thrips, and whiteflies
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PLANT DISEASE SYMPTOMS
Viruses
Can also be maintained:
on or inside seeds
in pollen
in certain root-infecting fungi
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PLANT DISEASE SYMPTOMS
Viruses Tobacco Mosaic Virus
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PLANT DISEASE SYMPTOMS
Viruses cause:Dead areas on leaves
Abnormal growthReduced growth, death
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PLANT DISEASE SYMPTOMS
Viroids
Piece of genetic material
Has no protein coatDivert plant metabolism to
produce more viroids
Spread by vegetative
propagation
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PLANT DISEASE SYMPTOMS
Potato spindle tuber viroid
Short, upright, stunted growth
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PLANT DISEASE SYMPTOMS
Mycoplasmas, Spiroplasms, andPhytoplasms
Similar to bacteriaHave no cell wall
Found in the infected plant water-
and food- conducting vesselsLeaf hoppers transmit mycoplasmas
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PLANT DISEASE SYMPTOMS Mycoplasmas, Spiroplasms, and
Phytoplasms
cause:
Growth abnormalitiesYellowing
Short internodes
Distortion of leaf and flower tissue
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PLANT DISEASE SYMPTOMS
Stubborn disease of citrusSpiroplasma
Uneven fruit size, reduction
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Carrot aster yellows phytoplasm
Yellowing of foliage, hairy rootsand internal root necrosis
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PLANT DISEASE SYMPTOMS
NematodesMicroscopic worms
Found in the soilOccurs in weeds and other plants
Spread by man
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Nematodes
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Nematodes cause:Abnormal growth or galls
Reduced growth, death
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PLANT DISEASE SYMPTOMS
Parasitic vascular plantsDodder, mistletoe, witchweed,Indian pipes, beech drops
Gain nutrients by parasitizing seed-
bearing plants
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PLANT DISEASE SYMPTOMS
Parasitic vascular plantsDodder
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Parasitic vascular plantsMistletoe
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Parasitic vascular plantsWitchweed
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PLANT DISEASE SYMPTOMS
Parasitic vascular plantsIndian pipes
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Parasitic vascular plantsBeech drops
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PLANT DISEASE SYMPTOMS
Wilts
Rots
Root Rot Blights
Leaf Spots or Blotches
Cankers Growth or Galls
Leaf Abnormality
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Plant Disease Symptoms
Wilt
Vascular system affected
Tomato Rhododendron
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Plant Disease SymptomsRots
Internally affecting plants
May be wet or dry rot
Examples: Fruits, Vegetables,
Trees
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PLANT DISEASE SYMPTOMSRoot Rot
Affects the fine feeder rootsDisease agent enters the crown
With above ground symptoms
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Plant Disease Symptoms
BlightsGeneral death of a plant part or plant
Fire blight Late blight
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Leaf Spots or Blotches
Dogwood Tomato Dogwood
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Cankers
Sunken areas in wood
Fungal structures associatedDeath of plant parts
Rose Spruce
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PLANT DISEASE SYMPTOMS
Growth or Galls
Cell enlargement and division
Bacteria, Fungi, Virus, Nematodes
Euonymous Forsythia Tomato
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PLANT DISEASE SYMPTOMS
Leaf Abnormality
Oak Rose
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A DISEASE SIGN
Structures produced by the causalagent of that disease that are more
specific than symptoms and are
more useful in the accuratediagnosis of a disease
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PLANT DISEASE MANAGEMENT
The incitant or pathogen alone
does not
bring about the disease.
Four factors are needed.
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FOUR FACTORS NEEDED
FOR A DISEASE TO OCCUR Host or susceptible plant
Environment Pathogen or disease causing agent
Time for the disease to occur
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Plant Disease Management
Based on the Disease TriangleSeed selection
Plant selection/resistance
Planting/fertilization/weed careSanitation (removal,pruning, clean-up)
Rotation
Pesticides