Download Summary of Diseases and Insects

Integrated Pest Management
Methods
• People who practice IPM (integrated pest
management) understand that eradicating insect
pests and diseases of plants is usually unrealistic.
• IPM primarily consists of methods used to prevent
plant problems from occurring in the first place.
Pest Management Methods
• To practice IPM in the landscape, choose plants that
are well suited to the site.
• Plant them properly and keep the plants healthy by
carefully watering, fertilizing, and pruning them.
Classification of Pesticides
• Pesticides
• A substance or mixture of substances used to control undesirable plants
and animals
• Insecticides
• Pesticides used to control unwanted insects
• Fungicides
• Designed to control fungal pathogens
Insect Development
or Metamorphosis
• Two forms of development
(change)
1. Simple/ Partial/ Primitive
2. Complete/ Advanced
Simple metamorphosis
Egg- nymph- adult
All life stages look similar, behave similar
Whole family can live and feed together
Simple(gradual) Metamorphosis
Complete Metamorphosis
•Egg -Larvae-Pupae-Adult
•
•
•
•
Larvae not look like adult- are wormlike
Can live in different environment
Eat different food
Larvae usually the main pest
Larva and
Pupae Stage
Adult
Male & Female
Insect Development
• Cold blooded- development
influenced by temperature
• Most insects inactive below 50 0 F;
• Breed, eat, develop faster the
warmer it is up to 95 0 F.
Insect mouthparts-two types
• Chewing
mouthparts
damage
• Sucking
mouthparts
damage
The Disease Triangle
All factors present disease can result
Methods of control can modify the triangle
Susceptible Host
Host
No
Disease
No
Disease
No
Disease
Disease
No
Disease
Pathogen
No
Disease
No
Disease
Environment
Causes of Plant Diseases
Biotic factors (biological in origin)
Fungi
Bacteria
Viruses
Nematodes
Phytoplasmas
Abiotic factors (non-biological)
Weather
Environmental pollutants
Plant Diseases: Fungi
• Largest pathogen group
• Over 200,000 known species of fungi
• More than 8,000 cause plant diseases
• Reproduce by asexual and sexual means
• Spores are like seeds
Signs of Fungal Diseases
• Powdery Mildew
• White coating on plant
• sprinkled with powdered sugar
Signs of Fungal Diseases
• Rust
Black Spot of Elm,
Gnomonia ulmea
• Lesions
• Angular appearance
• Fungal lesions more
irregular shape
Blights
Alternaria leaf blight caused by
Alternaria solani (left) and
Septoria leaf blight caused by
Septoria lycopersici (right)
• Cankers
• Lesions on stems,
branches or trunks
• Sunken and discolored
• Outer bark fallen away
• Rots
• Destruction and disintegration of a large
portion of the plant
• Affected areas are discolored and soft
• Crown rots
• Root rots
Southern blight
Sclerotium rolfsii
• Wilts
• Indicate plant is not getting water
• Plants have a droopy appearance
• Root rots
• Root system decayed, no longer
absorb water
Cineraria with root rot
Pythium
• Wilts
• Vascular wilt invades the xylem (water conducting tissue)
• Vascular discoloration or browning
• Xylem changes from whitish color to brown, green or gray color
Verticillium
Bacterial Wilt
of Cucumber
carried by
Cucumber Beetle
Plant Diseases: Bacteria
• Second most important group of plant pathogens
•
•
•
•
•
•
Spots
Lesions
Blight
Rots
Vascular wilts
Galls
Galls
Bacterial infections can cause
galls to form
Bacterium induces gall
formation by injecting it’s
own DNA into a plant cell
Crown gall
Plant Diseases: Viruses
• Reproduce by taking over host reproductive machinery
• Often associated with insect vectors
• Reproduction can take place in vector
• Can be transmitted mechanically
• Grower handling issues
• Plants rubbing together
Symptoms of
Viral Diseases
• Mosaic
• Mottling
• Leaf and Fruit Distortions
• Ringspot
• Mosaic
• Classic symptom
• Blotchy light and dark green coloring on leaves
• Poinsettia mosaic virus
• Rose Mosaic Virus
• Interesting lines and patterns
• Mottle
• Blotchy coloring occurs on flowers of other colored flower parts
Economic Importance
• Some cases of viral
infections can be
highly desirable
• Tulips
• Leaf and Fruit Distortions
• Leaves are narrow or “strappy”, thicker then normal
• Leaves are curled and twisted
• Fruit has warts (yellow raised bumps)
Zucchini
• Ringspot
• Concentric ring patterns on fruit or leaves
• Papaya ringspot
Plant Diseases: Phytoplasmas
• Odd bacteria like organisms
• Much smaller than bacteria, need an electron microscope
• Transmitted by insects usually leafhoppers
• Leafhoppers are phloem feeders
Symptoms of
Phytoplasma Diseases
• Virescence
• Brooming
• Fasciation
• Twisting and Distortion
• Virescense
• Normally colored plant parts are green
• Brooming
• Plant parts become overly branched and bushy
• Brooming - Ash Yellows
• Fasciation
• Flattening of plant parts
Maple branch
• Twisting, Distortion and Virescence
• Cosmos with Aster Yellows
Plant Diseases: Nematodes
• Parasitic worms
• Very complex compared to other pathogens
• Usually seen only with a light microscope
• Reproduce by eggs
• Nematodes
• Identified by extracting from soil or infected
• Non-pathogenic vs. pathogenic nematodes
• Pathogenic have a stylet
plant material
• Modified tooth that punctures and feeds on plant tissue
• Gall formation by nematodes
• Nematode tunnels into the root
• It’s saliva stimulates plant root cells to divide
Plant Diseases:
Abiotic Factors
• Nutritional abnormalities
• Pesticide exposure
• Environmental pollutants
• Adverse weather conditions
Symptoms
• Abnormalities are called INJURIES
• Discolortion
• Yellowing
• Chlorosis
• Reddening
Types of
Nutrient Abnormalities
• Yellowing at margins of leaf
• lack of molybdenum
• General yellowing
• lack of nitrogen
• Leaf veins remain green and leaf blades turn yellow
• lack of iron or manganese
• Reddening of foliage
• lack of phosphorus
• Molybdenum deficiency on poinsettia
• Yellowing at margins
• Pesticide exposure
• Curling and cupping
• Geranium exposed to the herbicide 2,4-D
• Pesticide exposure
• Twisting
• Tomatoes exposed to the herbicide 2,4-D
• Pesticide exposure
• Distortion
• Rose exposed to a phenoxy-type herbicide
• Symptoms similar to viruses and phytoplasmas
• Gather information
• Pesticide exposure
• Fungicide use can cause marginal burning
• Follow the label directions
• Environmental Pollutants
• Browning of arborvitae due to dog urine
• Environmental Pollutants
• Cold injury
• Candles starting to grow and cold weather comes
• Gather information
• Environmental Pollutants
• Heat injury
• High temps can cause tissue damage
• Environmental Pollutants
• Adverse weather conditions
• Winter injury
• Air temps rise but soil temps are cold
• Plant begins growing but the roots can’t get water to the foliage
• Plant desiccates and dies
• Environmental Pollutants
• Adverse weather conditions
• Drought stress, reddening of branches
Where to go for help…
• Plant Disease Diagnostics Clinic
• http://www.plantpath.wisc.edu/pddc/index.html
• Soil and Plant Analysis Lab
• Nutritional disorders
• http://uwlab.soils.wisc.edu/
Slides in power point are copy write:
 1999 by the Board of Regents of the University of Wisconsin
System doing business as the division of Cooperative
Extension of the University of Wisconsin Extension