Download pest_diseases

Pests and Diseases
28.00: Examine distinguishing
characteristics of pests so as to determine
best management practices.
29.00: Compare methods of control of
horticulture plant pests.
What is an insect?
• Small animals that have three
body regions and three pairs of
legs equaling six legs
• Body regions
– head
– thorax
– abdomen
Types of Insects
• The five types of mouthparts are
important in identifying and
controlling insects.
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Chewing
Piercing
Rasping
Siphoning
Sponging
Chewing Insects
• Insects tear, chew or grind food
• Examples
– grasshopper
– beetle
Piercing Insects
• Punctures plant and sucks the sap
Rasping insect
• Rasps or breaks surface and
sucks sap
• Example
– thrips
Siphoning insects
• Have a coiled tube they dip into
liquid food such as nectar and
draw it in
• Example
– butterfly
Sponging Insects
• Have two sponge-like structures
that collect liquid food and move
it into the food canal
• Example
– housefly
Life Cycles
• Complete metamorphosis has four
stages
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egg
larva-worms or caterpillars
pupa
adult-flies, beetles, etc.
Life Cycles
• Incomplete metamorphosis has
three stages
– egg
– nymph
– adult
Life Cycles
Chewing Insects
• Parts of leaves are eaten away
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beetles
cutworms
caterpillars
grasshoppers
Chewing Insects
• Beetles
– eat leaves, stems, flowers, fruit and
nuts
• Cutworms
– usually attack stems, but may eat
other plant parts
Chewing Insects
• Caterpillars
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larva of moths and butterflies
fuzzy or hairy
eat young leaves and stems
roll up in leaves making leaves curl
• Grasshoppers
– eat all parts of plants
Sucking Insects
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Aphids
Leaf bugs
Mealy bugs
Scale
Thrips
Whiteflies
Aphids
• Pierce and suck juices
• known as plant lice
• cause stunted growth and yellow
spotted leaves
• causes sticky substances and
black mold
• will attract ants
Aphids
Leaf Bugs
• Cause plants to look unhealthy
• plants will lose their normal color
and wilt
Leaf Bugs
Mealy Bugs
• Pierce and suck from underside
of leaves and in leaf axils causing
yellow appearance and sticky
secretions
Mealy bugs
Scale
• Appear as black or brown raised
lumps attached to stems and
underside of leaves causing yellow
leaves and stunted growth
Scale
Thrips
• Chew and then suck causing plant
tissue to become speckled or
whitened, leaf tip to wither, curl
up, or die
Thrips
Whiteflies
• Feed on underside of young leaves
causing yellowing
• will look like flying little white
specks when plants are shaken
Whiteflies
Mites
• Attack underside of leaves
causing gray to grayish-green
spots
• severe infestations cause
webbing
Mites
Plant Diseases
Diseases
• A disease is a plant disorder
caused by an infectious pathogen
or agent
Diseases
• There are 3 conditions necessary
for diseases in plants
– host plant
– disease causing organism or
pathogen must be present
– favorable environment for disease
organism to develop
Pathogens
• There are four groups of
pathogens
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bacteria
fungi
viruses
parasitic plants (attach to plants)
• mistletoe
• dodder
• lichens
Blight
• Causes plants to quickly turn
brown or black as if they had
been burned
Blight
Canker
• Causes open wounds on woody
plants
Canker
Damping off
• A fungal disease that causes
young plants and seedlings to rot
off at soil level
Damping Off
Gall
• Swellings or growths on plants
Leaf Spots
• Rings of different shades of
brown, green or yellow that make
spots on leaves
Mildew
• Grows on leaf surfaces--both
upper and lower--as white, gray
or purple spots
Mosaic
• Caused by viruses that make the
leaves have irregular mottled
areas with patterns ranging from
dark green to light green to
yellow to white
Mosaic
Rots
• Cause plant to decay and die
Rust
• Causes small spots on leaves that
resemble yellow, orange, brown or
red rust mainly on the underneath
side of leaves
Rust
Smut
• A black, powdery disease that
causes blisters that burst open
releasing black spores
Smut
Wilt
• A disease that blocks the uptake
of water in plant stems causing
plants to wilt
Wilt
Controlling Pests and
Diseases
Disease Control
• Preventing plant diseases is
better than treating the diseases
• Plant diseases must be identified
before they can be treated
Environment
• Warm temperatures and moist
conditions in greenhouse plant
production make most
horticulture plant diseases worse
because of environmental
conditions that support diseasecausing pathogens
Controlling Insects
• Insects can be controlled using
the following methods:
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biological
chemical
cultural
mechanical
natural
quarantine
Biological Control
• Uses natural enemies such as
birds, other insects, etc.
Chemical Control
• The use of pesticides or
insecticides
• Insects must be killed when they
are actively feeding or moving on
the plant
Chemical Control
• Contact poisons
– affect the insect’s nervous system
and must come into contact with the
insect to be effective
• Fumigants
– poisonous gases released into an
enclosed place so that insects
breathe the gases
Chemical Control
• Stomach poisons
– sprayed on the plant surfaces or are
taken into the plant through
absorption.
– The insect must suck the poison to
get it into the stomach for this
method to be effective.
– Systemic poisons are more
effective for controlling sucking
insects.
Cultural Control
• Involves sanitation, removing
insect breeding and hiding areas
and using insect resistant plant
varieties
Mechanical Control
• Uses physical control such as
insect traps, using screens over
fans and other openings, and
washing plants with soapy water.
Natural Control
• Methods include natural barriers
such as rivers, woods, mountains
and predators to control insects.
Quarantine
• Physically isolates insects from
healthy plants
IPM
• A combination of control methods
is called Integrated Pest
Management or integrated
control.