Chemicals used in plant production

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

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

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

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.

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

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

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

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.

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