Identifying and managing plant pest in fruit and vegtables 1

Horticulture Science
Lesson 39
Identifying and Managing Plant Pests in
Fruits and Vegetables


Interest Approach
Ask students to describe the “perfect” apple. What
characteristics do they look for when picking an apple?
After students list these traits, ask them to tell you
the things that can make an apple undesirable. What
causes these undesirable characteristics?


Student Learning Objectives
•Identify insect and disease pests of fruits and
vegetables.
•Analyze methods of pest management for
fruits and vegetables.


Terms
• aphids
• apple maggot
• aster yellows
• Botrytis blight
• brown rot
• cabbage worms
• cankers
• codling moth

Terms
• Colorado potato beetle
• corn earworm
• cucumber beetles
• damping-off
• fireblight
• leaf spots and blights
• pathogen


Terms
• peach tree borer
• plum curculios
• root and stem rots
• rusts
• San Jose scale
• scab
• slugs
• verticillium wilt


What insect and disease pests affect the growth of
fruits and vegetables?
• Like any other crops, fruits and vegetables have pests.
• These pests can impair fruit or vegetable growth and
production.
• Damage to fruits and vegetables can be enough to leave
them worthless to the grower.
• Hundreds of insects affect the growth and yield of fruit and

vegetable crops.


What insect and disease pests affect the growth of
fruits and vegetables?
• These pests can cause damage in a number of different
ways.
– The most obvious way insects can affect plants is by
consuming the foliage or fruit.
– Result in poor quality and contamination of the edible parts
of the fruit or vegetable crop.
– Insects can also do damage by piercing plants and sucking
nutrients from them.
– Insects also spread disease.
– The consumer generally does not tolerate the presence of
insects on or in fruits or vegetables.
– Most products must be free of insect pests to be marketable.


What insect and disease pests affect the growth of
fruits and vegetables?
1. Aphids are pear-shaped, soft-bodied, usually
wingless insects.
– They are often green or yellowish in color.
– Aphids have the ability to reproduce very rapidly.
– Astonishingly, they give birth to live young that are born
pregnant!
– Aphids use their mouthparts to pierce plants and suck out
juices.
– Aphids attack a wide variety of fruit and vegetable plants.

What insect and disease pests affect the growth of
fruits and vegetables?
2. Cabbage worms attack cabbage, broccoli, lettuce,
and other related crops.
– They are 1-inch-long green cabbage looper or butterfly
larvae.
– They eat holes in the leaves and flowers.


What insect and disease pests affect the growth of
fruits and vegetables?
3. The Colorado potato beetle is a yellowish ½-inchlong beetle with brown stripes.
– It eats potatoes, peppers, tomatoes, and eggplant.


What insect and disease pests affect the growth of
fruits and vegetables?
4. Cucumber beetles eat holes in the leaves of
cucumbers, melons, and squash.
– They are about ¼ inch in size.
– Their bodies are yellowish with black stripes.
– They also carry cucurbit wilt disease.


What insect and disease pests affect the growth of
fruits and vegetables?
5. The corn earworm is a
greenish-brownish striped

caterpillar about 1 inch
long.
– It feeds on the tip of the
ear.


What insect and disease pests affect the growth of
fruits and vegetables?
6. The peach tree borer attacks stone tree fruit,
including peaches, plums, nectarines, apricots, and
cherries.
– It damages the inner bark from about 12 inches above the
ground to about 3 inches below the ground.
– Serious infestations cause individual branches or entire trees
to die.


What insect and disease pests affect the growth of
fruits and vegetables?
7. The apple maggot infests apples, plums, and
blueberries.
– The adult fly emerges between June and September.
– It lays an egg inside the skin of a developing fruit.
– The larva tunnels through the flesh of the fruit.


What insect and disease pests affect the growth of
fruits and vegetables?
8. The San Jose scale is a pest of apples, pears, peaches,
apricots, plums, and cherries.

– The scale feeds on branches, leaves, and fruit.
– Infested fruit drops, branches lose vigor and die, and leaves
and fruit have a red spotted appearance.


What insect and disease pests affect the growth of
fruits and vegetables?
9. The codling moth is a serious pest of the apple.
– The larva damages the apple by burrowing into the center of
the fruit.
– As the larva chews its way inward, it pushes fecal material
through the opening.


What insect and disease pests affect the growth of
fruits and vegetables?
10. Plum curculios attack apples, peaches, pears,
plums, and cherries.
– Larvae tunnel through the fruit and cause the fruit to drop or
rot.


What insect and disease pests affect the growth of
fruits and vegetables?
• There are three main causes of fruit and vegetable
diseases.
• The pathogens that cause plant disease are fungi,
bacteria, and viruses.
• For one of these pathogens to infect a plant, the
environmental conditions must be right, the host plant

must be susceptible, and the pathogen, or the cause of
disease, must be present.


What insect and disease pests affect the growth of
fruits and vegetables?
1. Root and stem rots are caused mostly by Pythium,
Phytophthora, Rhizoctonia, and Fusarium fungi.
– When plant roots and stems rot, plant growth becomes
stunted, and the plant wilts easily.
– Pythium is one fungus that can cause damping-off.
– Damping-off is the early death of seedlings that have
germinated.
– More mature plants can also develop root and stem rots as a
result of Pythium, particularly when the growing medium has
poor aeration.
– Rhizoctonia causes damping-off, as well as root and stem
rots.


What insect and disease pests affect the growth of
fruits and vegetables?
2. Aster yellows is a viral disease of brambles and other
crops.
– Symptoms of infection include discoloration of plant tissues,
stunting of growth, and deformed growth.
– The spread from one plant to another is primarily by feeding
insects.

What insect and disease pests affect the growth of
fruits and vegetables?
3. Rusts are fungal diseases of apple, hawthorn, juniper,
and other species.
– Symptoms of rust are bright yellow, orange, orange-red,
reddish-brown, darkbrown, or black powdery raised pustules
on leaves, stems, and fruit.
– Leaves may wither and die, and plants may be stunted.


What insect and disease pests affect the growth of
fruits and vegetables?
4. Scab is a fungal disease common to crab apples and
apples, but other species are also affected.
– Initially, small light brown to olive-green lesions appear on
the undersides of leaves.
– The spots turn black; the leaves may curl; and if the petioles
are infected, the leaves drop.


What insect and disease pests affect the growth of
fruits and vegetables?
5. Leaf spots and blights are caused by fungi and
bacteria.
– They are common with many vegetables and fruits.
– Most leaf spot diseases appear as small, scattered, round to
oval dead areas.
– The appearance of the lesions varies.

What insect and disease pests affect the growth of
fruits and vegetables?
6. Cankers have a variety of causal agents.
– A canker is a localized dead area in the cambium and bark of
a branch or trunk.
– Cankers may appear sunken, flat, or swollen.
– They are typically discolored.
– Cankers can enlarge and girdle the stem, resulting in the
death of all tissue beyond the infection.