Weeds L5

Question 1

4 approaches to weed management

Answer 1

Prevention, eradication, control, management

Question 2

Weed prevention

Answer 2

preventing the introduction, establishment, and spread of weed species in areas not currently infested

Question 3

Weed eradication

Answer 3

the complete elimination of all live weeds, weed parts, and weed seed from an area

Question 4

Weed control

Answer 4

Reducing weeds to minimize weed competition and provide the greatest economic return from the crop

Question 5

Weed management

Answer 5

the combination of the techniques of prevention, eradication, and control to manage weeds in a crop, cropping system, or environment

Question 6

Forms of integrated weed management

Answer 6

Mechanical (physical) control
Cultural control
Biological control
Chemical control

Question 7

Every weed management option is a ____________ on the weed population

Answer 7

selection pressure

Question 8

What is the most practical approach to weed management?

Answer 8

weed prevention

Question 9

Weed prevention practices

Answer 9

avoid using crop seed infested with weed seed
clean farm machinery thoroughly before moving to a different field
monitor field for new weed problems and remove them before they get out of hand
compost manure prior to field application

Question 10

Common methods of mechanical weed control

Answer 10

hand-pulling
hoeing
mowing
tillage

Question 11

Hand-pulling

Answer 11

physical removal of weeds by hand
effective against annuals, biennials, and upper portions of perennials

Question 12

Hoeing

Answer 12

Cheap method of removing weeds
effective against annuals and biennials, but less effective on perennials because it only destroys top growth

Question 13

Mowing

Answer 13

Machine operated practice that should be done before flowers open to prevent seed production
more effective on tall weeds than short ones

Question 14

What does mowing success on weed management depend on

Answer 14

repeated mowing to deplete weed’s food reserve
mowing should be done between full leaf development and flowering because food reserves are the lowest

Question 15

tillage

Answer 15

non-chemical weed control that removes weeds from soil and buries them
works best under dry, hot conditions

Question 16

How does tillage influence weed composition?

Answer 16

increases # of perennial and annual species that have seeds with long life spans
type and frequency of tillage influences composition and density of weed species

Question 17

Pre-seeding tillage

Answer 17

prepares seed bed so planting occurs at uniform depth and controls weeds prior to seeding

Question 18

negative effects of pre-seeding tillage

Answer 18

lose moisture and cause erosion, inhibiting successful crop establishment

Question 19

post-harvest tillage

Answer 19

shallow tillage that avoids burying weed seed that is effective in controlling winter annuals, biennials, and some perennials

Question 20

Smmerfallow tillage

Answer 20

Shallow tillage to avoid bringing weed seed to surface that is partially effective in controlling perennials and dormant seeds of annuals

Question 21

post seeding tillage

Answer 21

done by harrowing, rotary hoeing, or using a rod-weeder to kill weeds that emerge before the crop (important to ensure that crop has not sprouted in the tillage zone)

Question 22

At what conditions will you receive the best result when using post-seeding tillage

Answer 22

a warm sunny day when the soil is dry

Question 23

post-emergence tillage

Answer 23

done on weeds that emerge shortly after crop
tillage cannot be deep and a certain amount of crop damage is likely to occur

Question 24

Row-crop tillage

Answer 24

Crops are planted in wide rows to allow for inter-row tillage (can cause more weed germination so multiple passes are necessary)

Question 25

Flooding

Answer 25

roots and shoots of weeds are covered by water for long periods of time to deprive weed of air

Question 26

Mulching (smothering)

Answer 26

use of non-living material/mulch to exclude light from weeds

Question 27

allelopathic mulches

Answer 27

crop species that release allelopathic chemicals that can be used to retard weed growth

Question 28

Example of allelopathic mulch

Answer 28

crop residues of fall rye incorporated into soil to inhibit weed species like wild oat Sweet clover as green manure

Question 29

soil solarization

Answer 29

Transparent and opaque polyethylene sheets are placed on moist soil to produce high soil temps that kills weeds (seedling/seed) and pathogens

Question 30

Flaming (burning)

Answer 30

use of flames generating a high enough temp over a sustained period of time to kill weeds and seed within top soil layer

Question 31

Cultural weed control

Answer 31

crop management practices that optimize the growth of crop plants and enable the crop to compete more effectively with weeds

Question 32

Crop rotation effect on weed control

Answer 32

can have greater weed control effect than tillage (especially when using weed suppressing cover crops)

Question 33

Seeding date effect on weed control

Answer 33

Seeding time is the main factor that determines weed composition as it is essential that the crops develop a good uniform stand in order to compete

Question 34

Benefits of delayed seeding

Answer 34

offers tillage options before seeding and after harvest to control early germinating weeds

Question 35

Types of weeds that can be controlled by late seeding

Answer 35

controls wild oat, wild buckwheat, and certain mustard species

Question 36

how does varying seeding dates limit weeds ability to adapt

Answer 36

doesn't allow them to germinate earlier or later to avoid control methods

Question 37

seeding rate effect on weeds

Answer 37

Increasing seed rates 20-50% above normal can increase competitiveness of some species (can only be increased to a certain limit)

Question 38

What does increased seed rate do to the crop

Answer 38

Earlier crop maturity (few days) Reduced tillering and shorter Higher yield (to a certain limit) increase competition, disease, and lodging losses

Question 39

When should increased seed rates be used

Answer 39

when either post-seeding or post-emergence tillage is planned to compensate for any crop damage

Question 40

Seeding depth effect on weeds

Answer 40

Seeds are placed at optimum depth to allow quick and even emergence to give crops better competitive ability

Question 41

What does optimum seeding depth depend on?

Answer 41

crop species seed size soil type and moisture conditions

Question 42

General rule for seeding depth

Answer 42

planted around 2-3 times as deep as the height of the seed

Question 43

Row spacing effect on weeds

Answer 43

narrow spacing means less open space for weeds to grow and offers better competition advantages for less competitive crops

Question 44

Plant nutrition effect on weeds

Answer 44

insuring soil nutrients is balanced to keep crop healthy and give it a better advantage