KEEPING PLANTS
HEALTHY
Unit E: MANAGING PESTS IN
PLANTS
FIVE MAJOR CATEGORIES OF
PESTS
PEST: Anything that causes plants
injury or damages them
INSECTS
NEMATODES
DISEASES
WEEDS
RODENTS
CHARACTERISTICS OF
INSECTS
Insects have three pairs or 6 legs.
Insects body is divided into three
sections: head, thorax and abdomen.
FIVE TYPES OF MOUTH PARTS
CHEWING : Bite off, chew and grind
parts of plants; examples include
grasshoppers, beetles and armyworms.
PIERCING-SUCKING : Suck sap from
a plant; examples include aphids,
chinch bugs, thrips, squash bugs and
leafhoppers.
Rasping-sucking – rasps or breaks
surface and sucks the sap EX: thrips
Siphoning – a coiled tube they dip into
liquid food (nectar)
Sponging – have 2
spong-like structures
that collect liquid
food and move it
into the food canal
Ex: housefly
METAMORPHOSIS
FOUR STAGES
1. EGG
2. LARVA – worms or caterpillars
3. PUPA
4. ADULT – flies, beetles, etc.
Examples of insects with complete
metamorphosis include moths and
butterflies, beetles and boll weevils.
INCOMPLETE
METAMORPHOSIS
1. EGG
2. NYMPH
3. ADULT
EXAMPLE IS A GRASSHOPPER
Insects must be killed
when that are actively
feeding or moving on
the plant.
WAYS INSECTS ARE
BENEFICIAL
IMPROVE THE SOIL - Allow air to
enter the soil or bury decaying
parts of plants: ants, wild bees and
beetles.
HELP POLLINATE PLANTS Spread pollen from plant to plant:
bees, butterflies, wasps and
beetles.
DESTROY
INSECTS - Attack
and destroy
harmful insects:
lady beetles,
dragon flies, wasps
and ants.
Damage to plants by pests
Insects – damage depends on types of
mouthparts
Chewing - parts of leaves eaten away
Beetles – eat leaves, stems, flowers and fruit
Cutworms – usually attach stems
Caterpillars – larva of moths; eat young leaves
and stem; make leaves curl
Grasshoppers – eat all parts of the plant
Damage from Sucking insects
Aphids – pierce and suck juices, called
plant lice. Causes stunted growth and
yellow spotted leaves. Sticky substance
and black mold will appear on leaves,
followed by ants eating the sticky stuff.
Sucking
Mealy bugs –
Pierce and suck from underside of
leaves and in the leaf axils
causing yellow appearance
Sucking
Scale – appear as black or brown raised lumps
attached to stems and underside of leaves
causing yellow leaves and stunted growth
Sucking
Thrips
Chew and then suck causing plant tissue to
become speckled or whitened, leaf tip to
wither or curl up or die
Whiteflies
Feed on underside of leaves causing
yellowing. They will look like flying little
white specks when plants are shaken or
moved.
Plant Diseases
Disease – a plant disorder caused
by an infectious pathogen or agent
3 things needed for disease
Host plant
Disease causing organism or
pathogen
Favorable environment for disease
MAJOR TYPES OF PLANT
DISEASES
ENVIRONMENTAL
1. Nutrient deficiencies
2. Damage to plant parts
3. Chemical injuries
4. Pollution injuries
5. Weather
6. Naturally-occurring genetic
abnormalities
PARASITIC
1. Fungi
2. Bacteria
3. Viruses
4. Parasitic plants –
like mistletoe,
lichens attach
themselves to a
host plant and suck
food & life from it
Plant diseases must be
identified before they can be
treated
Warmth and moist environment
of greenhouses make plant
diseases worse.
Blight
Plants quickly turn brown or black as if
they have been burned
Canker
Causes open wounds on wood plant
stems
Damping Off
Damping off is a
fungal diseases that
causes young plants
and seedlings to rot
off at soil level.
Galls ~
round 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 surface as
white, gray or purple
spots.
Looks like powder.
Rot ~
cause plant to decay and die.
Usually caused by excessive
moisture
Rust ~ causes small spots on
leaves that resemble yellow,
orange, brown or red rust
mainly on the underneath
side of leaves.
Smut ~
a black powdery disease that
causes blisters that burst
open releasing
black spores.
Wilt ~
diseases that block the
uptake of water in plant
stems causing plants
to wilt.
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.
Preventing plant diseases is
better than treating the
diseases.
PROBLEMS THAT WEEDS
CAUSE
Weed: Any plant growing in
an unwanted area
Keep plants from growing
Waste nutrients
Lower quality of crop
Make harvesting harder
Hiding place for insects and disease
Look bad
CONDITIONS NEEDED FOR A
PEST TO CAUSE PROBLEMS
A PEST MUST EXIST
A SUSCEPTIBLE PLANT
THE RIGHT ENVIRONMENT
WAYS THAT PESTS DAMAGE
PLANTS
Pests
Pests
Pests
Pests
Pests
Pests
chew holes in plants
attack the vascular system
attack the fruit
contaminate products
rob plants of food
damage land
Biological uses natural
Ways to control pests:
enemies such as birds, other
insects, etc.
Lady bugs – eat aphids, so they
help the gardener control a bad
insect
Chemicals using poisons: insecticides
Contact poisons affect the insect’s nervous system
and must come into contact with insect to be
effective.
Stomach poisons are sprayed on plant surfaces or
are taken into the plant through absorption. The
insect must eat or suck the poison to get it into the
stomach. Most effective for chewing insects.
SYSTEMIC POISONS - Poison is absorbed by the
plant and when insects bites or sucks its juice, it gets
poison. Systemic poisons are more effective for
controlling sucking insects like scale.
FUMIGANTS – poisonous gases released into
greenhouse and insects breath the gases
WAYS TO PREVENT PEST
PROBLEMS
Use good seed
Destroy diseased plants
Use the right fertilizer
Disinfect equipment
Use good water
Control animal movement
Use chemicals properly
Use tests to check for pests
CULTURAL PRACTICES
Cultural involves sanitation,
removing insect breeding and
hiding areas and using insect
resistant plant varieties.
ROTATING CROPS
ROGUING
TRAP CROPPING
BURNING
USING RESISTANT VARIETIES
MECHANICAL METHODS OF
PEST CONTROL
Mechanical uses physical control such
as insect traps using screens over fans
and other openings and washing plants
with soapy water.
PLOWING
MOWING
MULCHING
PESTICIDES
Chemicals used to control pest
Insecticides - controls insects
Nematocides - controls nematodes
Fungicides - controls fungi
Bactericides - used to control bacteria
Herbicides - used to control weeds
TYPES OF HERBICIDES
SELECTIVE HERBICIDES - Will only kill
certain kinds of plants.
NON-SELECTIVE HERBICIDES - Used to
kill all vegetation where they are applied.
TRANSLOCATED HERBICIDES - Absorbed
into the plant and moved all through its
parts; upset the growth process of weeds.
NON-CHEMICAL MEANS OF
CONTROLLING PESTS
BIOLOGICAL PEST CONTROL -
Using living organisms to control pests.
GENETIC METHODS - Develop crops
that are resistant to pests
IPM
INTEGRATED PEST MANAGEMENT is a
planned process for controlling pests.
Involves using a blend of pest control
techniques in a planned program
Field of crops is managed as an ecosystem
IPM has fewer adverse effects on the
environment.
SAFETY PRACTICES IN
PEST CONTROL
Use only approved pesticides
Know the pesticide
Use the pesticide with low toxicity
Use pesticides only when needed
Do not contaminate resources
Wear protective clothing
SAFETY PRACTICES IN PEST
CONTROL
Wash the skin after contact
Dispose of empty containers properly
Apply in good weather
Use the right equipment
Know the emergency measures