Pests and Diseases - PowerPoint PPT Presentation

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.

• Small animals that have three body regions and three pairs of legs equaling six legs
• Body regions
• head
• thorax
• abdomen

• The five types of mouthparts are important in identifying and controlling insects.
• Chewing
• Piercing
• Rasping
• Siphoning
• Sponging

• Insects tear, chew or grind food
• Examples
• grasshopper
• beetle

• Punctures plant and sucks the sap

• Rasps or breaks surface and sucks sap
• Example
• thrips

• Have a coiled tube they dip into liquid food such as nectar and draw it in
• Example
• butterfly

• Have two sponge-like structures that collect liquid food and move it into the food canal
• Example
• housefly

• Complete metamorphosis has four stages
• egg
• larva-worms or caterpillars
• pupa
• adult-flies, beetles, etc.

• Incomplete metamorphosis has three stages
• egg
• nymph
• adult

• Parts of leaves are eaten away
• beetles
• cutworms
• caterpillars
• grasshoppers

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

• Caterpillars
• 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

• Aphids
• Leaf bugs
• Mealy bugs
• Scale
• Thrips
• Whiteflies

• Pierce and suck juices
• known as plant lice
• cause stunted growth and yellow spotted leaves
• causes sticky substances and black mold
• will attract ants

• Cause plants to look unhealthy
• plants will lose their normal color and wilt

• Pierce and suck from underside of leaves and in leaf axils causing yellow appearance and sticky secretions

• Appear as black or brown raised lumps attached to stems and underside of leaves causing yellow leaves and stunted growth

• Chew and then suck causing plant tissue to become speckled or whitened, leaf tip to wither, curl up, or die

• Feed on underside of young leaves causing yellowing
• will look like flying little white specks when plants are shaken

• Attack underside of leaves causing gray to grayish-green spots
• severe infestations cause webbing

• A disease is a plant disorder caused by an infectious pathogen or agent

• 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

• There are four groups of pathogens
• bacteria
• fungi
• viruses
• parasitic plants (attach to plants)
• mistletoe
• dodder
• lichens

• Causes plants to quickly turn brown or black as if they had been burned

• Causes open wounds on woody plants

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

• Swellings or growths on plants

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

• Grows on leaf surfaces--both upper and lower--as white, gray or purple spots

• Caused by viruses that make the leaves have irregular mottled areas with patterns ranging from dark green to light green to yellow to white

• Cause plant to decay and die

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

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

• A disease that blocks the uptake of water in plant stems causing plants to wilt

• Preventing plant diseases is better than treating the diseases
• Plant diseases must be identified before they can be treated

• Warm temperatures and moist conditions in greenhouse plant production make most horticulture plant diseases worse because of environmental conditions that support disease-causing pathogens

• Insects can be controlled using the following methods:
• biological
• chemical
• cultural
• mechanical
• natural
• quarantine

• Uses natural enemies such as birds, other insects, etc.

• The use of pesticides or insecticides
• Insects must be killed when they are actively feeding or moving on the plant

• 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

• 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.

• Involves sanitation, removing insect breeding and hiding areas and using insect resistant plant varieties

• Uses physical control such as insect traps, using screens over fans and other openings, and washing plants with soapy water.

• Methods include natural barriers such as rivers, woods, mountains and predators to control insects.

• Physically isolates insects from healthy plants

• A combination of control methods is called Integrated Pest Management or integrated control.