R2103 2.1 – 2.3 Weeds COPY Flashcards
What is meant by a weed?
A plant of any kind growing out of place.
Name 3 ways weeds cause problems.
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.
What is meant by ephemeral weeds?
Give 2 examples.
Has several life cycles in one growing season
E.g. Cardamine hirsuta (hairy bitter dress)
Capsella bursa pastoris (shepherd’s purse)
State what is meant by an annual weed.
Complete their life cycle within one year.
E.g. Poa annua
Veronica persica (speedwell)
State what is meant by “perennial weed” and name 2 examples.
Lives through several growing seasons or has a life cycle of more than 2 years.
E.g. Ranunculus repens
Aegopodium podagraria (ground elder)
State 2 weeds associated with recently cultivated soil.
Cardamine hirsuta Stellaria media (chickweed) Veronica persica (speedwell)
State 2 weeds associated with herbaceous borders.
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
State 2 weeds associated with woody perennial plantings.
Aegopodium podagraria (Ground elder)
Rubus fruticosus
Calystegia sepium
State 2 weeds associated with lawns.
Poa annua
Ranunculus repens
Plantago major
What is meant by “contact herbicide”?
Name one, and its active ingredient.
Name a situation for its use.
Kill or damage plants where they enter.
Weedol - acetic acid
Clearing paths and patios.
State what is meant by “translocated” or “systemic” herbicide.
Name one.
Where could it be used appropriately?
Absorbed by the plant and distributed around all parts of plant, so good for perennial weeds.
Glyphosate (Roundup).
Clearing uncultivated ground.
State what is meant by “selective herbicide”.
Name one.
Where best used?
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.
Name for ground elder
Aegopodium podagraria
Name a contact herbicide and its ingredient.
Weedol - acetic acid
What are “contact herbicides”?
Chemicals that kill plant tissues they come into contact with. But do not move about to any extent within the plant.
When to use contact herbicides?
Controlling annual weeds and perennial weed seedlings in between garden plants, as long as the plants are protected (cover with polythene).
Translocated herbicides?
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.
When to use translocated herbicides?
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.
What are selective (hormone) herbicides?
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.
Where are selective (hormone) herbicides used?
Commonly used practice on lawns and sports greens.
Active ingredients in contact herbicide?
Acetic acid (e.g. ready-to-use spray – WEEDOL FAST ACTING GUN!)
Active ingredients in translocated (systemic) herbicide?
Glyphosate (e.g. ready to use spray – FAST ACTION ROUNDUP)
Active ingredients in selective (hormone) herbicide?
Selective (hormone) herbicide – fluroxypyr or clopyralid (e.g. liquid concentrate – WEEDOL LAWN WEEDKILLER)
NAME ONE herbicide (active ingredient) to control perennial weeds in lawns. And the mode of action.
2,4D, Mecoprop-P, MCPA.
Selective translocated herbicides.