Unit B Lesson B14 Crops, Pests, and Sustainability
Completion requirements
Lesson B14: Crops, Pests, and Sustainability
Video Lesson
Crop yields can be reduced by insects, fungi, or weeds. Watch the video below to learn more about how people use pesticides and herbicides to increase crop yields.
Lesson B14: Crops, Pests, and Sustainability
Figure B.4.14.1 – Purple Loosestrife is from Europe and Asia. In North America, it crowds out other plant species.
Figure B.4.14.2 – Oxeye daisies are an invasive species on Alberta’s prairie and parkland.
Invasive Plants
Invasive species are plants that are not native to an area and that spread rather quickly. They are introduced to a new area by humans, often for good reasons such as beautiful flowers. However, these plants become invasive because they have no or few natural enemies in the new area. This means that invasive plants can grow quickly. They take nutrients and space from native plants that are trying to grow.
Invasive species are plants that are not native to an area and that spread rather quickly. They are introduced to a new area by humans, often for good reasons such as beautiful flowers. However, these plants become invasive because they have no or few natural enemies in the new area. This means that invasive plants can grow quickly. They take nutrients and space from native plants that are trying to grow.
For example, the dandelion is an invasive plant that quickly takes over fields, parks, and lawns, crowding out other plants such as grasses. Likely, it arrived first in North America among the seeds brought by early settlers. Purple loosestrife likely
came to North America in the 1700s in soil used as ballast on ships coming here for various products, and it might have hitch-hiked on raw wool brought here from Britain. Purple loosestrife grows quickly in wetlands and does not leave space for other
wetland plants such as cattails. It disturbs the natural wetland habitat for other species, including insects and birds. Oxeye daisy arrived from Europe and Asia, and it spread quickly especially in pastures and grasslands. Grazing animals such as
cattle and deer don’t like them! Invasive species continue to spread despite efforts to prevent or to stop them. A new one in Alberta is jimsonweed, which appeared in some canola fields in 2015.
Reading and Materials for This Lesson
Science in Action 7
Materials:
Science in Action 7
Reading: Pages 160–167
Materials:
clipboard, paper, pencil or pen
Watch More
Invasive Plants
Invasive plants change natural ecosystems. Watch this video to learn more about how conservation workers keep invasive plants under control.
Invasive plants change natural ecosystems. Watch this video to learn more about how conservation workers keep invasive plants under control.
Chemical Pesticides and Herbicides
Pesticides and herbicides are chemicals sprayed on crops to kill pests and weeds. Some pesticides stop insects from eating crops. Others stop fungi from growing on plant leaves and leaving the crop inedible. Herbicides kill weeds, stopping them from using soil nutrients the desired crops can use.
Pesticides and herbicides increase crop yields and reduce the costs of food. This is important because seven billion people on Earth must have affordable food.
Using pesticides and herbicides has disadvantages, too. They can cause harm to species other than plants.
For example, DDT is a pesticide that is very effective at killing insects. Huge amounts of DDT were used on farms from 1940 to 1960. DDT was declared illegal in many countries after scientists discovered that it harms other species, including humans. DDT harms birds of prey such as eagles and falcons, making their eggshells weak and easy to break. This stops the development of baby birds. DDT was discovered to damage the ability of humans to have healthy babies.
Pesticides and herbicides are chemicals sprayed on crops to kill pests and weeds. Some pesticides stop insects from eating crops. Others stop fungi from growing on plant leaves and leaving the crop inedible. Herbicides kill weeds, stopping them from using soil nutrients the desired crops can use.
Pesticides and herbicides increase crop yields and reduce the costs of food. This is important because seven billion people on Earth must have affordable food.
Using pesticides and herbicides has disadvantages, too. They can cause harm to species other than plants.
For example, DDT is a pesticide that is very effective at killing insects. Huge amounts of DDT were used on farms from 1940 to 1960. DDT was declared illegal in many countries after scientists discovered that it harms other species, including humans. DDT harms birds of prey such as eagles and falcons, making their eggshells weak and easy to break. This stops the development of baby birds. DDT was discovered to damage the ability of humans to have healthy babies.
Figure B.4.14.3 – Tractors are used to apply pesticides or herbicides to farm fields.
Figure B.4.14.4 – Small airplanes that spray pesticides or herbicides on crops are called crop dusters.
Lesson Activity
Pesticide Controversy
In this activity, you will learn more about the controversy over the use of pesticides. You will collect information on both sides of the issue. This lesson activity will help you with your Section 4 Assessment.
Download:
DOWNLOAD this document. It has a chart that will help you organize the information you learn from watching the pesticide videos.
In this activity, you will learn more about the controversy over the use of pesticides. You will collect information on both sides of the issue. This lesson activity will help you with your Section 4 Assessment.
Download:
DOWNLOAD this document. It has a chart that will help you organize the information you learn from watching the pesticide videos.
Instructions:
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Construct a table with two columns. You can do this on a sheet of paper, type it, or can use the table in document you downloaded from the link just above.
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Title the columns “Examples of Pesticide Advantages” and “Examples of Pesticide Disadvantages”.
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Watch these videos. As you watch the videos, listen for examples of advantages and disadvantages to using pesticides. Pause the video when you hear an example and summarize the example in the correct column of your table
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Save your table. It will be useful for your Section 4 Assessment.
These first three short videos explain the reasons farmers choose to use pesticides.
How plant science technologies impact consumers at the grocery store
Why do farmers use pesticides?
Pesticides Needed for Growing Global Food Demand
A Zest for Pests
This video gives an effective overview of pesticides.
This video gives an effective overview of pesticides.
Pesticide regulation in Canada
This video explains how the government of Canada makes rules for safe pesticide use.
This video explains how the government of Canada makes rules for safe pesticide use.
Pesticides causing controversy
This video explains why the use of pesticides is controversial.
This video explains why the use of pesticides is controversial.
The buzz about pesticides
This video explains how pesticides can affect pollinating bees.
This video explains how pesticides can affect pollinating bees.
Popular Weed Killer Stirs Health, Environmental Concerns
This video explains the good and bad aspects of using a pesticide called atrazine.
This video explains the good and bad aspects of using a pesticide called atrazine.
Pesticides in tea: How much chemical residue is in your cup?
This news report explains how high levels of pesticides were found in teas.
This news report explains how high levels of pesticides were found in teas.
Connections
Figure B.4.14.5 – Food grown without any human-made chemicals is called organic food.
Figure B.4.14.6 – Organic food is sold in many grocery stores.
Connections: Health and Wellness
>> Organic Food
Crops grown without the use of chemical pesticides, herbicides, or fertilizers and are non-GMO plants are called organic crops. Organic farms and foods are increasing in popularity because many people do not want to risk eating chemicals that might remain on plants.
The downside to organic food is the cost of production. Workers must be paid to do jobs that chemicals can do, such as removing weeds. Also, organic food grows more slowly without chemical fertilizers. This means that organic farmers grow and sell less food compared to farmers using chemicals. Organic farmers charge more money for their crops to cover their business costs.
>> Organic Food
Crops grown without the use of chemical pesticides, herbicides, or fertilizers and are non-GMO plants are called organic crops. Organic farms and foods are increasing in popularity because many people do not want to risk eating chemicals that might remain on plants.
The downside to organic food is the cost of production. Workers must be paid to do jobs that chemicals can do, such as removing weeds. Also, organic food grows more slowly without chemical fertilizers. This means that organic farmers grow and sell less food compared to farmers using chemicals. Organic farmers charge more money for their crops to cover their business costs.
Figure B.4.14.7 – Many people believe eating organic foods promotes a healthy lifestyle.
Figure B.4.14.8 – Organic food must be certified by inspectors before it can be labelled as organic.
Watch More
Organic Farming
Watch this video to learn more about the rules for classifying organic food.
Watch this video to learn more about the rules for classifying organic food.
Some organic farmers have switched back to using chemicals on their farms. Watch this video to learn why.
Biopesticides
Biopesticides are plants, bacteria, or insects that get rid of harmful pests naturally. For example, ladybugs and praying mantises eat smaller insects such as aphids. Some gardeners buy these insects to put in their gardens.
A natural pesticide can be obtained from the seeds of chrysanthemum flowers, which contain a substance that is toxic to insects. In small amounts, it is not toxic to humans. Chrysanthemum seeds have been ground into powder and brushed on plants for many centuries.
Sometimes, gardeners make non-toxic pesticides from household ingredients. One natural pesticide can be made by combine cooking oil, biodegradable liquid soap, and water. Spraying this mixture on plant leaves helps kill small insect pests.
Biopesticides are plants, bacteria, or insects that get rid of harmful pests naturally. For example, ladybugs and praying mantises eat smaller insects such as aphids. Some gardeners buy these insects to put in their gardens.
A natural pesticide can be obtained from the seeds of chrysanthemum flowers, which contain a substance that is toxic to insects. In small amounts, it is not toxic to humans. Chrysanthemum seeds have been ground into powder and brushed on plants for many centuries.
Sometimes, gardeners make non-toxic pesticides from household ingredients. One natural pesticide can be made by combine cooking oil, biodegradable liquid soap, and water. Spraying this mixture on plant leaves helps kill small insect pests.
Figure B.4.14.10 – The praying mantis is a large insect that eats smaller insects.
Figure B.4.14.11 – Ladybugs eat aphids. Aphids harm many types of plants by sucking out their sap.
Figure B.4.14.12 – Chrysanthemum seeds contain a natural pesticide.
Watch More
Biopesticides
Watch this video to learn about how wasps are used as a biopesticide.
Watch this video to learn about how wasps are used as a biopesticide.
This video explains how certain plants can help control weeds.
Try It!
Biodiversity in Your Backyard
Try this activity to find out how much plant biodiversity is in your backyard or in a nearby park. If it’s wintertime, you might need to look at bare trees and branches or rely on your memory to list types of plants that grow in the area.
Try this activity to find out how much plant biodiversity is in your backyard or in a nearby park. If it’s wintertime, you might need to look at bare trees and branches or rely on your memory to list types of plants that grow in the area.
Materials:
Instructions:
- clipboard
- paper
- pencil or pen
Instructions:
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Choose a location in the middle of your backyard or in a nearby park.
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From where you are standing, turn slowly in a circle. Each time you see a different type of plant, stop and write its name on your sheet. Be sure to include trees, grasses, shrubs, and garden plants. If you do not know the name of the plant, describe
its location and its appearance.
- Count the list of all the various plants you saw. Did the number surprise you? Would you say that around your home (or in the park) has lots of biodiversity or little biodiversity?
Seed Banks
Humans can decrease biodiversity by activities such as deforestation. This makes scientists concerned that some plant types might become extinct. To save important seeds for the future, they have organized seed banks. Seed banks are buildings that store seeds just in case a plant goes extinct. In addition, seed banks contain instructions on the best growing conditions for each type of seed.
Figure B.4.14.13 – Seeds are important to the survival of plant species.
Watch More
Seed Banks
Watch this video to learn more about the Millennium Seed Bank where billions of seeds are stored.
Watch this video to learn more about the Millennium Seed Bank where billions of seeds are stored.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to
guide your learning.
Unit B Lesson 14 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
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REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
- CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Self-Check Time!
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Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
Kudzu is an invasive plant. In the United States; no animals or insects naturally eat kudzu. When kudzu takes over an area, it prevents other plants from thriving.
Pesticides stop insects from eating and destroying crops. Pesticides allow food to be grown quickly and inexpensively, which feeds increasing numbers of people in the world.
Pesticides sometimes can be harmful to the health of other species.
Protecting biodiversity is important because biodiversity helps ecosystems stay healthy. Any species is dependent on other species in an ecosystem. The extinction of a plant or animal affects the health of many other species in the ecosystem.
The green lacewings are acting as a biopesticide in the garden. These larger insects eat the smaller aphids, protecting the garden plants from being eaten by aphids.