1. Chemicals used in plant production

2. In this lesson you will be learning about the other chemicals used in growing plants.
Also you will be asked to think about alternatives to using chemicals.
By the end of the lesson you should:
Be able to discuss why chemicals are used in growing plants
Be able to discuss the alternatives to using chemicals

3. There are 3 main groups of chemicals (other than fertilisers) used in growing plants
Herbicides
Fungicides
Insecticides

4. Herbicides These are used to treat other plants that are
weed species (not wanted plants)
Weed plants could include:
common ragwort
creeping or field thistle
spear thistle
curled and broad-leaved dock

5. Herbicides To control these weeds two type of herbicide are used
Contact herbicides:
- kill on contact with plant tissue
- usually sprayed on
- often do not kill perennial plants.
Systemic herbicides:
- sprayed on
- will control perennial plants
- they spread through the plant to the roots.

6. Fungicides These are used to treat fungi that are damaging the crop.
Fungi could include:
Grey moulds on leaves and fruits
Rusts and fungi on cereal crops

7. Fungicides
To control fungal diseases, antifungal chemicals are sprayed on to the crops
- either in the fields or after harvesting.

8. Insecticides These are used to treat insect pests that damage crops
Insect pests could include:
Aphids (greenfly)
Weevils
Beetles
Controlling insect pests
Insecticide chemicals are sprayed onto crops

9. Controlling pests in other ways
Chemical control of pests is relatively new
over the past 100 years.
Other methods exist to control pests without the use of so many chemicals.
These are called biological controls
Includes:
introducing predators of pest species,
removing by hand
using soapy solutions to spray on plants.

10. Why use alternatives to chemicals?
Research
Why are the use of chemical pesticides thought to be harmful?
Produce a word document of your research