Pests & Diseases

Insects - Anatomy

•Insects▫Small animals that have three body regions

and three pairs or six legs.▫The three body regions are….

Head Thorax Abdomen

Parts of the Insect

Life Cycle of Insects

•Complete metamorphosis▫Egg▫Larva

Worm Caterpillar

▫Pupa▫Adult

Flies Beetles

Life Cycle of Insects

•Incomplete metamorphosis▫Egg▫Nymph▫Adult

Insects - Mouthparts

•Chewing▫Tear, chew or grind food.

▫Parts of leaves eaten away.

▫Example: Grasshoppers Beetles.

Insects - Mouthparts

•Piercing-sucking▫Punctures plant & sucks sap.

•Rasping-sucking▫Rasps or breaks surface and suck sap.▫Example: Thrips

Insects - Mouthparts

•Siphoning▫Have a coiled tube they dip into liquid food

such as nectar and draw it in.•Sponging

▫Have two sponge-like structures that collect liquid food and move it into the food canal.

▫Example: Housefly

Insect Damage

•Damage depends on type of mouthparts.

Chewing Insects

•Beetle▫Eat leaves, stems,

flowers, fruit and nuts.

Chewing Insects

•Cutworms▫Usually attack

stems, but may eat other plant parts.

Chewing Insects

•Caterpillars▫Larva of moths and butterflies and are fuzzy

or hairy.▫Eat young leaves and stems.▫Roll up in leaves making the leaves curl.

Chewing Insects•Grasshoppers

▫Eat all parts of plants.

Sucking Insects

•Aphids▫Pierce & suck

juices.▫Known as plant lice.▫Cause stunted

growth and yellow spotted leaves.

▫Causes sticky substance and black mold which attracts ants.

Sucking Insects

•Leaf Bugs▫Causes plants to

look unhealthy.▫Lose their normal

color and wilt.

Sucking Insects

•Mealybugs▫Pierce and suck from underside of leaves

and in leaf axils.▫Causes yellow appearance and sticky

secretions.

Sucking Insects

•Scale▫Appear as black or brown raised bumps

attached to stems and underside of leaves ▫Causes yellow leaves and stunted growth.

Sucking Insects

•Thrips▫Chew & then suck

plant tissue causing it to become speckled or whitened, leaf tips to wither, curl up or die.

Sucking Insects

•Whiteflies▫Feed on underside

of young leaves causing yellowing.

▫They will look like flying little white specks when plants are shaken.

Mite Damage

•Mites▫Aren’t insects

because they have 8 legs.

▫Attack underside of leaves causing gray to grayish-green spots.

▫Severe infestations cause webbing.

Controlling Insects

Controlling Insects

•Insects must be killed when they are….▫Actively feeding or moving on the plant.

Biological Control

•Using natural enemies such as….▫Birds▫Other insects.▫Etc.

Chemical Control

•Using pesticides or insecticides (chemicals).

Chemical Control

•Contact Poisons▫Affect the insect’s nervous system and must

come into contact with insect to be effective.

Chemical Control

•Stomach Poisons▫Are sprayed on

plant surfaces or are taken into the plant through absorption.

▫Insect must eat or suck the poison to get it into the stomach for this method to be effective.

Chemical Control

•Systemic Poisons▫Absorbed by the

plant and then ingested by the pest when it feeds.

▫More effective than stomach poisons for controlling sucking insects.

Chemical Control

•Fumigants▫Poisonous gases released into an enclosed

place so that insects breathe the gases.

Cultural Control•Involves sanitation, removing insect

breeding and hiding areas and using insect resistant plant varieties.

Mechanical Control

•Using physical controls such as….▫Insect traps. ▫Using screens

over fans & other openings.

▫Washing plants w/ soapy water.

Natural Methods

•Using natural barriers to control insects such as….▫Rivers▫Woods▫Mountains▫Predators

Quarantine

•Physically isolating insects from healthy plants.

Combining Methods

•Using a combination of control methods is called….▫Integrated Pest Management (IPM) or….▫Integrated Control

Plant Diseases

What is a Disease???•A plant disorder caused by an

infectious pathogen or agent.

Conditions Needed for a Disease•Three conditions are necessary for a

disease in a plant.▫Host plant▫Disease causing organism or pathogen

must be present.▫Favorable environment for disease

organism to develop.

The Disease Triangle

What Causes a Disease??

•The groups of pathogens are….▫Bacteria▫Fungi▫Viruses▫Parasitic plants

Mistletoe Dodder Lichens

FUNGI

Parasitic Plants

LICHENSMISTLETOE DODDER

Controlling Diseases

•Warm temperatures and moist conditions in greenhouse plant production make most horticulture plant diseases worse because….▫Environmental conditions that support disease-

causing pathogens.•Preventing plant diseases is better than

treating the diseases.•Plant diseases must be identified before

they can be treated.

Plant Diseases – Blight

•Cause plants to quickly turn brown as if they had been burned.

Plant Diseases – Canker

•Causes open wounds on woody plant stems.

Plant Diseases – Damping Off

•A fungal disease that causes young plants and seedlings to rot off at the soil level.

Plant Diseases – Galls•Round swellings or growths on plants.

Plant Diseases – Leaf Spots

•Rings of different shades of brown, green, or yellow that make spots on leaves.

Plant Diseases – Mildew

•Grows on leaf surfaces (both upper & lower) as white, gray or purple spots.

Plant Diseases – 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.

Plant Diseases – Rot

•Causes plants to decay & die.

Plant Diseases – Rust

•Causes small spots on leaves that resemble yellow, orange, brown or red rust mainly on the underneath side of leaves.

Plant Diseases – Smut

•A black powdery disease that causes blisters that burst open releasing black spores.

Plant Diseases – Wilts

•Disease that blocks the uptake of water in plants stems causing it to wilt.