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. 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 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 beetles cutworms caterpillars grasshoppers

Chewing Insects Beetles Cutworms eat leaves, stems, flowers, fruit and nuts Cutworms usually attack stems, but may eat other plant parts

Chewing Insects Caterpillars Grasshoppers 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 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 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 disease-causing pathogens

Controlling Insects Insects can be controlled using the following methods: 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 Fumigants 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.