Transcript Topic 6

Topic 6
Pests and Pest Control
What is a pest?

Every year tonnes of chemicals are used to
control pest organisms that reduce plants’
ability to produce food and fibre.
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From the point of view of a farmer or
forester, a pest is an organism that is
causing plants to die or produce less than
otherwise would.
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Insects are not the only type of pest,
however: Fungi, weeds, and other animals
such as slugs or birds can also be pests in
certain situations.
The Pest Problem
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In natural systems, organisms have parasites,
predators, or competing plants that help keep
their numbers in check.
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The pests that cause the most damage are
insects, fungi, and weedy plants.
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Weeds are thieves, they steal moisture,
nutrients, space, or light from the crop. Insects
usually eat some part of the plant and fungi
and bacteria can cause infections, destroying
parts or all of the plant.
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Insects and diseases consume over 50 percent
of Canada’s annual harvest. Farmers spend
millions of dollars each year to control them
and avoid crop losses.
Dandelion : Profile of a
Champion
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1. Powerful roots – They have a powerful taproot that
is anchored deep in the soil. If you try to pull up a
dandelion it usually breaks off near the surface,
leaving most of the root in the soil. The rot can grow
new leaves and flowers.
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2. Broad leaves – Dandelion leaves are wide and
broad and they shade out nearby plants.
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3. Super Seeds – Dandelions are able to produce
flowers and seeds all summer long.
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4. Adaptable – Dandelions grow well in all kinds of
soil, including soil that is poor in nutrients.
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Chemical weapons – Dandelions release chemical
agents to slow down the growth of other grass and
other plants nearby.
Canola and Its Pests
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Canola is popular with fungi, insects, and weeds.
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Canada Thistle
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Fusarium Fungus
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Wild Oats
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Bertha Army Worm
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Blackleg Fungus
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Lygus Bugs
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Sclerotina
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Diamond Black moths
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Flea beetles
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Blister beetles
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Aphids
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cinchbugs
Controlling Pests
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Larges pests could be chased or scared
away, and smaller pests could be picked off
or scared away.
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Crop rotation is a process where farmers
grow different crops each year as a way of
controlling some weeds and diseases.
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Herbicides, insecticides, and fungicides
controlled weeds, insects and fungi. These
chemicals are easy to use, give impressive
results, and were considered safe as well as
inexpensive.
Bioaccumulation
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The pollutants from chemicals move from level
to level in the food chain and get stored in the
same way food energy is stored.
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Some of the chemicals wash off the plants and
leave residues in the soil and water. If the
pesticides are not decomposed, they can stay
in the environment and remain poisonous.
Toxic residues have even been found in polar
ice caps thousands of kilometers from the
nearest source. Pesticides are often toxic to
more than one organism. In most cases,
beneficial organisms, which are not the target
of the chemical control, also die hen pests
organisms are killed.
Resistant Species
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Scientists have discovered that, as
pesticide use increases, the number
of species that can withstand the
effects (are resistant) is increasing as
well.
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The only way to target these new
tougher insects is to use harsher
chemicals. These higher dosages can
be even more harmful.
Organic Food
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Organic food is food that has been grown without the use of chemical
fertilizers and chemical pesticides. Instead, they use manure and
compost to add nutrients to the soil.
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They fight weeds using tilling, crop rotation, mulching, planting their crops
alongside plants that discourage insects, and removing insects by hand.
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Other practices include:
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Sowing good quality seeds
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Removing weeds before seeds mature
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Cutting weeds along the property line
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Cleaning the equipment well.
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Organic farmers often grow a variety of crops instead of monocultures.
Benefits include higher prices for produce, increased safety for the
farmer, and less chance to residue buildup.
Biological control
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Biological control means using a
pest’s natural enemy to control it.
For example, the soil bacteria
bacillus thuringienisis produces a
toxin that is deadly to certain insects
but is apparently harmless to
humans and other animals.
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Some farmers use ladybugs, wasps
or spiders to control aphids or white
flies.