R2103 2.1 – 2.3 Weeds

Question 1

What is meant by a weed?

Answer 1

A plant of any kind growing out of place.

Question 2

Name 3 ways weeds cause problems.

Answer 2

Reduction of plant growth and crop productivity as there is competition for water, light and nutrients.
Reduction of visual appeal of planting.
Can be hosts of pests and diseases e.g. Capsella bursa pastoris = club root.

Question 3

What is meant by ephemeral weeds?

Give 2 examples.

Answer 3

Has several life cycles in one growing season
E.g. Cardamine hirsuta (hairy bitter dress)
Capsella bursa pastoris (shepherd’s purse)

Question 4

State what is meant by an annual weed.

Answer 4

Complete their life cycle within one year.
E.g. Poa annua
Veronica persica (speedwell)

Question 5

State what is meant by “perennial weed” and name 2 examples.

Answer 5

Lives through several growing seasons or has a life cycle of more than 2 years.
E.g. Ranunculus repens
Aegopodium podagraria (ground elder)

Question 6

State 2 weeds associated with recently cultivated soil.

Answer 6

Cardamine hirsuta
Stellaria media (chickweed)
Veronica persica (speedwell)

Question 7

State 2 weeds associated with herbaceous borders.

Answer 7

Ephemerals and annuals can arise, but sometimes perennials such as Aegeopodium podagraria and Galium aparine.
Annuals: Taraxacum officinale
Lamium purpureum
Urtica dioica
Ranunculus repens
Senecio vulgaris

Question 8

State 2 weeds associated with woody perennial plantings.

Answer 8

Aegopodium podagraria (Ground elder)
Rubus fruticosus
Calystegia sepium

Question 9

State 2 weeds associated with lawns.

Answer 9

Poa annua
Ranunculus repens
Plantago major

Question 10

What is meant by “contact herbicide”?
Name one, and its active ingredient.
Name a situation for its use.

Answer 10

Kill or damage plants where they enter.
Weedol - acetic acid
Clearing paths and patios.

Question 11

State what is meant by “translocated” or “systemic” herbicide.
Name one.
Where could it be used appropriately?

Answer 11

Absorbed by the plant and distributed around all parts of plant, so good for perennial weeds.
Glyphosate (Roundup).
Clearing uncultivated ground.

Question 12

State what is meant by “selective herbicide”.
Name one.
Where best used?

Answer 12

Able to kill chosen weed species and leave others unaffected.
2, 4-D: hormone based, a selective, systemic herbicide approved for use in the EU and used for the control of broad-leaved weeds.

Question 13

Name for ground elder

Answer 13

Aegopodium podagraria

Question 14

Name a contact herbicide and its ingredient.

Answer 14

Weedol - acetic acid

Question 15

What are “contact herbicides”?

Answer 15

Chemicals that kill plant tissues they come into contact with. But do not move about to any extent within the plant.

Question 16

When to use contact herbicides?

Answer 16

Controlling annual weeds and perennial weed seedlings in between garden plants, as long as the plants are protected (cover with polythene).

Question 17

Translocated herbicides?

Answer 17

Can move from one part of a plant to another once they have been absorbed.
When applied to foliage, these will be translocated downwards to the roots, helping to control deep-rooted perennial weeds.
Action is slower than contact herbicides.
Non-selective and non-residual, breaking down quickly in the soil.

Question 18

When to use translocated herbicides?

Answer 18

Clearing weeds prior to cultivation of a weedy border or controlling deep-rooted perennials in an established border, as long as garden plants are protected.

Question 19

What are selective (hormone) herbicides?

Answer 19

The application of certain chemicals that destroy certain broad-leaved weeds whilst leaving grasses unharmed.
Often called hormone weed killers as they mimic plant hormones.
Cause rapid and distorted growth.
Applied to the foliage and are ‘translocated’.
Often slightly residual (i.e. stay in soil).
Many herbicides are available that contain a mix of selective herbicides to control a range of weeds.

Question 20

Where are selective (hormone) herbicides used?

Answer 20

Commonly used practice on lawns and sports greens.

Question 21

Active ingredients in contact herbicide?

Answer 21

Acetic acid (e.g. ready-to-use spray – WEEDOL FAST ACTING GUN!)

Question 22

Active ingredients in translocated (systemic) herbicide?

Answer 22

Glyphosate (e.g. ready to use spray – FAST ACTION ROUNDUP)

Question 23

Active ingredients in selective (hormone) herbicide?

Answer 23

Selective (hormone) herbicide – fluroxypyr or clopyralid (e.g. liquid concentrate – WEEDOL LAWN WEEDKILLER)

Question 24

NAME ONE herbicide (active ingredient) to control perennial weeds in lawns. And the mode of action.

Answer 24

2,4D, Mecoprop-P, MCPA.

Selective translocated herbicides.

Question 25

NAME ONE herbicide (active ingredient) to control perennial weeds in woody perennial planting. And the mode of action.

Answer 25

Glyphosate.

Non-selective/total translocated herbicide.

Question 26

Name ONE distinct chemical and its mode of action for Aegopodium podagraria in an established shrub border.

Answer 26

Glyphosate, which is translocated.

Question 27

Name ONE distinct chemical and its mode of action for Cardamine hirsuta in newly cultivated soil.

Answer 27

Acetic acid or fatty acid which have a contact mode of action.

Question 28

Name ONE distinct chemical and its mode of action for Ranunculus repens in an established lawn.

Answer 28

2,4-D or Fluroxypyr, which are selective herbicides.

Question 29

State the mode of action of ONE NAMED herbicide for the control of weeds in anherbaceous border.

Answer 29

Glyphosate, which is a translocated herbicide or Diquat, Acetic Acid or Fatty Acid which are all contact herbicides suitable for an herbaceous border.

Question 30

State ONE situation where a selective herbicide could be used, and the active ingredient.

Answer 30

Lawn or playing field e.g. 2, 4-D, MCPA or Dicamba

Question 31

State ONE situation where a contact herbicide could be used, and the active ingredient.

Answer 31

Paths or gravel e.g. Acetic acid, Fatty acids or Diquat

Question 32

Name TWO distinct weeds that could be controlled by a selective weed killer.

Answer 32

Ranunculus repens

Taraxacum officinale

Question 33

State TWO benefits and TWO disadvantages of using chemicals to control weeds.

Answer 33

Benefits:
 Translocated chemicals can kill the whole plant which prevents regrowth from the root.
 Chemicals can be residual which prevents germination of further weeds.
 Chemicals are quicker to apply than manual weeding.
 Chemicals can target specific weeds.
Disadvantages:
 Risk of spray drift onto other plants.
 Chemicals can contaminate the soil if used inappropriately.
 Need appropriate equipment and storage facilities for chemicals.
 There is a risk of pollution of water courses when using chemicals.

Question 34

What is the active ingredient in a translocated herbicide?

Answer 34

Glyphosate
2,4-D
MCPA
Mecoprop

Question 35

Describe TWO ways to avoid the growth of weeds in a lawn.

Answer 35

 Scarifying/aerating/top dressing the lawn, as appropriate, to maintain a healthy sward to avoid competition with weeds.
 Re-seed bare patches in the lawn to avoid weed seeds germinating.
 Ensure that borders adjacent to the lawn are kept weed free to prevent weed seeds being spread into the lawn.
 Frequent mowing to remove weed seed heads.

Question 36

Name TWO distinct perennial weeds found in lawns.

Answer 36

Taraxacum officinale, Bellis perennis, Plantago minor

Question 37

Name the active ingredient of TWO herbicides, stating their mode of action.

Answer 37

Diquat which is a contact herbicide

Glyphosate which is a translocated herbicide Propyzamide which is a residual (soil acting) herbicide