Explain why weeds need to be controlled.

**Describe what is meant by a weed, to include ‘a plant growing out of place’.

Describe how weeds cause problems to include:

• the reduction of plant growth, to include competition for light, nutrients and water.

• the reduction of the visual appeal of plantings.

• the role of weeds as alternate hosts for plant pathogens, to include white blister rust of brassicaceae and clubroot.**