chemical control

Question 1

what is the chemical mode of action for an annual weed in a gravel path?

Answer 1

A residual herbicide that is active.
eg: dichlobenil

it stays active for many months so do not use where you want to plant a crop.

Question 2

two benefits of chemical control are:

Answer 2

rapid control

easily available

Question 3

two limitations of chemical control are?

Answer 3

build up, so resistance

dangerous to humans, animals, plants

Question 4

what harm will glyphosate do to water sources and grass?

Answer 4

toxic to fish-esp in high temps

is a total weed killer so will kill off grass (don’t use on a lawn)

Question 5

what damage does 2,4-D do and to which plant?

Answer 5

spoil growth of tomatoes and prevent fruiting

Question 6

what does a contact herbicide do and give an example

Answer 6

enters leaf/stem and kills tissues.

Diquat can be used for annual weeds on waste ground

Question 7

explain translocated herbicides and given an example

Answer 7

enters leaf/stem/roots and moves via vascular system to kill whole weed.

used for perennial weeds as have underground roots
eg: Glyphosate for Ranunculus repens, Couch grass (Elymus repens)

Question 8

what do selective herbicides do and name an example/situation

Answer 8

kill chosen weed species via root or leaf but leave the crop along (think about mono and dicot on lawns etc)

Use 2,4-D on lawns. It is active.

Question 9

what is a residual herbicide?

Answer 9

contains active ingredients, and remains chemically stable for many months so is usually used on gravel paths away from garden plants

eg: diflufenican or dichlobenil to treat Poa annua (annual meadow grass)

Question 10

Name ephemeral weeds and where you will find them

Answer 10

Cardamine hirsuta
Capsella bursa-pastoris
Stellaria media

found in cultivated soil, fym

Question 11

name annual weeds

Answer 11

poa annua

Veronica persica

Question 12

name perennial weeds

Answer 12

Ranunculus repens

couch = Agropyron repens and Elymus repens

Question 13

what are the four different garden locations weeds can be found?

Answer 13

recently cultivated soil
herbaceous perennial border
woody perennial plantings
lawns

Question 14

name weeds in recently cultivated soil

Answer 14

couch grass-perennial (Agropyron repens)
chickweed
common speedwell

Question 15

name weeds in the herbaceous perennial border

Answer 15

taraxacum officinale

Question 16

name weeds in woody perennial plantings

Answer 16

couch grass= agropyron repens
elymus repens
aegopodium podagaria = kesh