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Botany > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

How were all weeds initially removed

A

By hand

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2
Q

How were all weeds removed 3000 years ago

A

Animals were used to drag a hoe

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3
Q

After what year were row crops weeded by horse hoeing

A

Year 1731

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4
Q

What year were tractors introduced

A

1920

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5
Q

When was the first herbicide introduced

A

In 1946

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6
Q

Name the first herbicide that was introduced

A

2,4-D kills dicots but not most monocots

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7
Q

How many species of weed affecting food crops

A

About 30,000

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8
Q

Give examples of annual weeds

A

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

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9
Q

Give example of Ephemeral weeds

A

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

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10
Q

What are Ephemeral weeds

A

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

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11
Q

Give examples of Biennial weeds

A

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

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12
Q

Give example of Perennial Weeds

A

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

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13
Q

Physiological characteristics for weed success

A

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

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14
Q

Reproductive characteristics for weed success

A

• 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

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15
Q

Agronomic characteristics for weed success

A

• 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

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16
Q

What are direction losses in weed competition

A

Loss due to competition for light , water and nutrients

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17
Q

Example of biochemical competition(ALLELOPATHY)

A

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

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18
Q

Name an example of proflic weed dispersal

A

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

19
Q

Name an example of explosive weed dispersal

A

Himalayan balsam
Spurge
Yellow wood sorrel

20
Q

Name an example of water weed dispersal

A

Himalayan balsam
Purple loosestrife
Dock spp

21
Q

Name an example of wind weed dispersal

A

Dandelion
Horse weed ( Conya candensis)

22
Q

Name an example of animal weed dispersal

A

Wild carrot
Curly dock

23
Q

Give an example of a weed as hosts for pests

A

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

24
Q

What disease does common chickweed cause (Stellaria media)

A

Tomato spotted wilt virus

25
Q

What disease does Field bindweed(Convolvulus arvensis) cause

A

Cucumber mosaic virus

26
Q

What disease does Mallow (Malva sp.) cause

A

Tomato yellow leaf curl virus

27
Q

What disease does Nightshade (Solanum sp.) cause

A

Potato virus Y

28
Q

What disease does Scarlet pimpernel (Anagallis arvensis) cause

A

Lettuce mosaic virus

29
Q

What disease does Barberry (Berberis sp.) cause

A

intermediate hosts for wheat stem rust

30
Q

Name the major weed of intensively managed high fertility grasslands

A

Dock

31
Q

Describe the weed Nettle

A

Grows in clumps
Prevents grazing

32
Q

Describe the weed Thistle

A

Discourages grazing
Makes hay and silage unpalatable

33
Q

Describe a cultural weed control

A

Stale seed bed
Crop rotation

34
Q

Describe a physical / mechanical weed control

A

Covering
Burying
Slashing
Mowing

35
Q

Describe a biological weed control

A

Herbivory
Competitive plants

36
Q

Describe a chemical weed control

A

Contact , systematic and residual , broad spectrum or selective herbicides

37
Q

When will annual weeds often disappear

A

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

38
Q

Name an example of a noxious weed

A

Ragwort (Senicio Jacobea)

39
Q

What animals is ragwort highly toxic to

A

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

40
Q

What happens to an animal who has ingested ragwort

A

Animals liver accumulates copper causing ill health and death

41
Q

Other than ragwort name 4 other noxious weeds

A

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

42
Q

Example of non-native invasive weeds

A

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

43
Q

What exactly is a weed

A

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

Botany (21 decks)

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