Lecture 4

Question 1

How were all weeds initially removed

Answer 1

By hand

Question 2

How were all weeds removed 3000 years ago

Answer 2

Animals were used to drag a hoe

Question 3

After what year were row crops weeded by horse hoeing

Answer 3

Year 1731

Question 4

What year were tractors introduced

Answer 4

1920

Question 5

When was the first herbicide introduced

Answer 5

In 1946

Question 6

Name the first herbicide that was introduced

Answer 6

2,4-D kills dicots but not most monocots

Question 7

How many species of weed affecting food crops

Answer 7

About 30,000

Question 8

Give examples of annual weeds

Answer 8

• Fat hen (Chenopodium album)
• Redshank (Polygonum persicaria)
• Annual nettle (Urtica urens)
• Charlock (Sinapsis arvensis)
• Red deadnettle (Lamium purpurium)
• Cleavers / Goosegrass (Galium aparine)

Question 9

Give example of Ephemeral weeds

Answer 9

• Groundsel (Senicio vulgaris)
• Hairy bittercress (Cardamine hirsuta)

Question 10

What are Ephemeral weeds

Answer 10

Completes more than one lifecycle in one season/ year, then dies

Question 11

Give examples of Biennial weeds

Answer 11

• Ragwort (Senicio jacobaea)
• Wild carrot (Daucus carota)

Question 12

Give example of Perennial Weeds

Answer 12

• Bishops weed / Ground elder (Aegopodium podagraria)
• Couchgrass (Agropyron repens) • Rhododendron ponticum
• Bracken (Pteridium aquilinum) • Dock (Rumex spp.)

Question 13

Physiological characteristics for weed success

Answer 13

• High photosynthetic rate
• Rapid seedling growth
• Produce seed early in the lifecycle
• Highly adaptable
• No special environmental conditions required

Question 14

Reproductive characteristics for weed success

Answer 14

• Self fertilised with some outcrossing
• Many seeds produced
• Seeds produced over a long period of time
• Will produce seed in unfavourable conditions • Pollinated by wind or many insect species
• Can reproduce vegetatively by stolons

Question 15

Agronomic characteristics for weed success

Answer 15

• Weed and crop may look and grow similarly • Seeds mature at the same time as crop
• Tolerance to herbicides
• Seed remains viable in soil for long periods • Soil disturbance bring seeds to the surface

Question 16

What are direction losses in weed competition

Answer 16

Loss due to competition for light , water and nutrients

Question 17

Example of biochemical competition(ALLELOPATHY)

Answer 17

• Juglans nigra (Black walnut)
• Alianthus altissima (Tree of heaven)
• Oryza sativa (Rice)

Question 18

Name an example of proflic weed dispersal

Answer 18

Groundsel 1000-1200 fruits
Mayweed 15,000 to 19,000 fruits
Rosebay willow herb - 80,000 seeds

Question 19

Name an example of explosive weed dispersal

Answer 19

Himalayan balsam
Spurge
Yellow wood sorrel

Question 20

Name an example of water weed dispersal

Answer 20

Himalayan balsam
Purple loosestrife
Dock spp

Question 21

Name an example of wind weed dispersal

Answer 21

Dandelion
Horse weed ( Conya candensis)

Question 22

Name an example of animal weed dispersal

Answer 22

Wild carrot
Curly dock

Question 23

Give an example of a weed as hosts for pests

Answer 23

Nematodes eg potato root eelworm
(Globodora spp.) grow on weed species of Solanum

Question 24

What disease does common chickweed cause (Stellaria media)

Answer 24

Tomato spotted wilt virus

Question 25

What disease does Field bindweed(Convolvulus arvensis) cause

Answer 25

Cucumber mosaic virus

Question 26

What disease does Mallow (Malva sp.) cause

Answer 26

Tomato yellow leaf curl virus

Question 27

What disease does Nightshade (Solanum sp.) cause

Answer 27

Potato virus Y

Question 28

What disease does Scarlet pimpernel (Anagallis arvensis) cause

Answer 28

Lettuce mosaic virus

Question 29

What disease does Barberry (Berberis sp.) cause

Answer 29

intermediate hosts for wheat stem rust

Question 30

Name the major weed of intensively managed high fertility grasslands

Answer 30

Dock

Question 31

Describe the weed Nettle

Answer 31

Grows in clumps Prevents grazing

Question 32

Describe the weed Thistle

Answer 32

Discourages grazing Makes hay and silage unpalatable

Question 33

Describe a cultural weed control

Answer 33

Stale seed bed Crop rotation

Question 34

Describe a physical / mechanical weed control

Answer 34

Covering Burying Slashing Mowing

Question 35

Describe a biological weed control

Answer 35

Herbivory Competitive plants

Question 36

Describe a chemical weed control

Answer 36

Contact , systematic and residual , broad spectrum or selective herbicides

Question 37

When will annual weeds often disappear

Answer 37

when they are out competed by a vigorous crop such as grass and may not need any treatment

Question 38

Name an example of a noxious weed

Answer 38

Ragwort (Senicio Jacobea)

Question 39

What animals is ragwort highly toxic to

Answer 39

cattle, horses, deer, goats, pigs and chickens.

Question 40

What happens to an animal who has ingested ragwort

Answer 40

Animals liver accumulates copper causing ill health and death

Question 41

Other than ragwort name 4 other noxious weeds

Answer 41

Creeping thistle (Cirsium arvense) Spear thistle (Cirsium vulgare) Curled Dock (Rumex crispus) Broad leaved Dock (Rumex obtusifolius)

Question 42

Example of non-native invasive weeds

Answer 42

Japanese Knotweed Giant Hogweed Giant Rhubarb Himalayan Balsam Montbretia (Crocosmia) Rhododendron ponticum

Question 43

What exactly is a weed

Answer 43

“Any plant not intentionally sown or propagated by the grower that requires management to prevent it from interfering from crop or livestock production”