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Weeds Test 1 > Study Guide > Flashcards

Study Guide Flashcards

1
Q

What are the negative impacts of weeds

A 
Allergies
Toxicity to humans and animals
Obstruction
Wildfires
Aesthetics
Water management problems
Harbor pests
Reduced crop quality
Control cost
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2
Q

How do crops cause crop production losses

A

Competition, allelopathy, harvest interference

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3
Q

What is a green bridge

A

Pest survives in crop residue from previous season and carries into the next season

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4
Q

What are the beneficial impacts of weeds we discussed

A 
Human food
Animal feed
Medicine
Insect-repellent chemicals
Host beneficial insects
Bioremediation
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5
Q

What are some plants cattle are likely to graze

A

Ragweed
Foxtail
Dandelion
Plantain

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6
Q

Compare and contrast the characteristics of an ideal annual weed and perennial weed

A

Annual: Prolific seed production, seeds survive extended times, resist control, quick maturation
Perennial: Deep roots, dual modes of repro, vigorous vegetative reproduction

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7
Q

What are some key id features of monocots that dicots do not have

A

ochrea

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8
Q

Compare and contrast a raceme and a panicle inflorescence

A

Raceme: pedicle holds flowers (branches off main stem)
Panicle: compound branching off stem (multiple layers)

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9
Q

What are some recommendations for using a dichotomous key

A

Read both choices
Don’t guess
If unsure, follow both choices
Make sure final description is accurate

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10
Q

How does knowledge of weed ecology help manage weeds

A

Enables prediction of which species may be problems in a system

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11
Q

What types of flowers make up a head inflorescence. Which plant family is associated with a head inflorescence

A

disc flowers

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12
Q

Which characteristics of an ideal weed are associated with an r-selected species? K-selected species?

A

r-selected: rapid growth, abundant seed production

K-selected: vegetative growth, taproot, defense mechanisms

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13
Q

Which adaptation strategy best describes most weeds found in crops. Why

A

C-R weeds

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14
Q

What are the characteristics of a C-strategist

A

Competitors
low disturbance, low stress
Large biomass, vegetative growth (similar to K-selected species)
mid-stages of succession

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15
Q

What are characteristics of an S-strategist

A

Stress tolerators
high stress, low disturbance
biomass production, defense mechanisms, extreme conditions
late stages of succession

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16
Q

What are characteristics of an R-strategist

A 
Ruderals
frequent disturbance, low stress
short lifespans and reproduce quickly (seed production)
similar to r-selected species
early stages of succession
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17
Q

Compare and contrast r/K selection theory and C-S-R theory

A

C similar to K

r similar to R

18
Q

What is the largest source of introduced weeds in North American cropping systems

A

Europe (western migration)

19
Q

Describe three patterns of plant invasion. Which is most difficult to control

A

Front: controlled movement forward
Streamers: localized extension
Satellite population: sending out seeds to distant locations apart from founding population

20
Q

What types of plants compete with each other

A

-

21
Q

What are some examples of disturbance mentioned in class

A

-

22
Q

What is plasticity? What are two types we discussed. Give examples

A

Phenotypic: change leaf shape
Physiological: change growth rate

23
Q

What are the characteristics of a habitat that is vulnerable to a plant invasion

A

Frequent disturbance
Less species richness
Excess resources

24
Q

Describe the rate of plant population growth during the three phases of plant invasion

A

Introduction: vigorous growth, numerous sites of introduction
Naturalization: plants in founding pop. become self-reproducing. Most plants do not survive without human help
Invasion: naturalized plants spread from founding pop. to cover more area (exponential population growth)

25
Q

How does the absence of natural enemies impact introduced plant species

A

exponential growth because no means of natural control

26
Q

What advantages make intentionally introduced species more invasive than accidentally introduced species

A

Cultivated

27
Q

How likely is an introduced plant to become invasive

A

very unlikely

28
Q

What is an early detection and rapid response system

A

organized, local efforts to locate and control satellite populations while growth rate sill in lag phase

29
Q

What information is necessary to predict the likelihood of a plant invasion

A

-

30
Q

What are the three components of plant interference

A

Competition
Allelopathy
Parasitism

31
Q

What parasitic plants are found in North America

A

witchweed, mistletoes, dodder, broomrape

32
Q

What seed adaptations might facilitate dispersal by animals

A

creating burs that stick to animal fur

33
Q

According to the critical weed free period theory, when is the best timing of weed control

A

-

34
Q

What factors lengthen the critical weed free period. What shortens it

A

when crops are more competitive, CWFP is longer, when weeds are more competitive, CWFP is shortened

35
Q

How does tillage affect weed seeds in the seedbank

A

fewer seeds on soil surface, more buried in the soil. Favors weeds that tolerate or need seed burial

36
Q

What portion of seeds in the seedbank are viable

A

10-50% are viable

37
Q

What is the relationship between seed size and seed number

A

inverse relationship

38
Q

Why would a crop producer scout for weeds at harvest

A

look for problem areas in order to prepare for weed management for the next season

39
Q

How is the critical weed free period determined for a given crop

A

when does yield loss start occurring and when does yield loss stop.

40
Q

Where do seeds in the seedbank come from

A

dead plants, rain, wind, animals, machinery

Weeds Test 1 (1 decks)

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