Introduction to
Plant Pests
Original Created By Margaret
ForChapman
AgEd 410
Spring 1999
Cal Poly, San Luis Obispo
Copied from Cal Poly
Modified by Georgia Agriculture Education Curriculum Office
August 2008
June 2002
Four main groups of plant
pests:
1. Weeds
2. Invertebrates
3. Vertebrates
4. Disease Agents
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Plant Pests
* Organisms that compete with
people for food or fiber, interfere
with raising our crops and
livestock.
* Proper identification is important
in controlling pests.
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Weeds
* Undesirable plants, sometimes
defined as “any plant growing out
of place.”
* Adapt well to local
climates and soils and
can compete successfully
with cultivated plants.
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* Most weeds
produce a large
number of seeds.
* Some weed seeds
can remain dormant
for 20 years before
germinating.
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* Weeds can be persistent and difficult
to eradicate, because some have
vegetative means of reproduction in
addition to seeds.
* Weeds compete with
agricultural crops for
water, nutrients, light
and space.
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* Weeds can interfere with farming
operations, and can harbor insects
and plant diseases.
* Some weeds are toxic to livestock.
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* A simple way to identify
weeds is to compare them
to colored photographs and
drawings.
* Become familiar with
plant classification system
and the weeds physical
features, developmental
stages,and life cycles.
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* We will discuss
weed and other pest
control measures in
upcoming lessons.
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Invertebrate Pests
* Includes insects and their relatives,
nematodes, snails and slugs.
* “Invertebrate” signifies animals
without backbones (no vertebrate).
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* Insects have three body parts: head,
thorax and abdomen and six legs.
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* Ticks, mites and spiders have only
two body parts and eight legs.
Spider
Tick
Mite
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* Nematodes are a large group of
unsegmented worms that can be
plant parasites.
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* Snails and slugs are mollusks that
prefer cool, moist surroundings.
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Vertebrates
* Animals with backbones
* Includes fish ,amphibians, reptiles,
birds and mammals.
* Most of our concern is with birds
and mammals.
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Pest birds
* Harbor pathogens, disease
causing organisms
* Eat or damage crops
* Cause damage to buildings
* Make too much noise
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* Rodents are mammals that interfere
with people, or cause harm to crops
and livestock.
* Animal pests are similar to weeds,
those that are out of place are considered
pests.
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Most of our vertebrate problems
are caused from:
* Rats
* Mice
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* Squirrels
Disease Agents
* Cause disease in plants and animals.
* Many are submicroscopic, making
identification difficult.
* If you can’t see the pest, then it may
be identified by the type of symptoms
caused or damage done.
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* Included in this group of pests are:
1. Bacteria
August 2008
Bacterial citrus canker
symptoms on citrus leaves
2. Fungi
August 2008
* Scab symptoms on
orange fruit caused by the
fungus Elsinoe fawcetti
3. Viruses
* Citrus tristeza Virus
on grapefruit
August 2008
* Potato Virus on
veins and shoots
Problems growers face
* Energy, time and expense to combat
problems.
* Losses of food to our world food supply
can become disastrous.
* Farmers are focusing on controlling
pests while dealing with environmental
pollution problems.
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* New methods and concepts continue to
evolve each day to keep our crops healthy
and abundant.
August 2008