Study Guide Flashcards
What are the negative impacts of weeds
Allergies Toxicity to humans and animals Obstruction Wildfires Aesthetics Water management problems Harbor pests Reduced crop quality Control cost
How do crops cause crop production losses
Competition, allelopathy, harvest interference
What is a green bridge
Pest survives in crop residue from previous season and carries into the next season
What are the beneficial impacts of weeds we discussed
Human food Animal feed Medicine Insect-repellent chemicals Host beneficial insects Bioremediation
What are some plants cattle are likely to graze
Ragweed
Foxtail
Dandelion
Plantain
Compare and contrast the characteristics of an ideal annual weed and perennial weed
Annual: Prolific seed production, seeds survive extended times, resist control, quick maturation
Perennial: Deep roots, dual modes of repro, vigorous vegetative reproduction
What are some key id features of monocots that dicots do not have
ochrea
Compare and contrast a raceme and a panicle inflorescence
Raceme: pedicle holds flowers (branches off main stem)
Panicle: compound branching off stem (multiple layers)
What are some recommendations for using a dichotomous key
Read both choices
Don’t guess
If unsure, follow both choices
Make sure final description is accurate
How does knowledge of weed ecology help manage weeds
Enables prediction of which species may be problems in a system
What types of flowers make up a head inflorescence. Which plant family is associated with a head inflorescence
disc flowers
Which characteristics of an ideal weed are associated with an r-selected species? K-selected species?
r-selected: rapid growth, abundant seed production
K-selected: vegetative growth, taproot, defense mechanisms
Which adaptation strategy best describes most weeds found in crops. Why
C-R weeds
What are the characteristics of a C-strategist
Competitors
low disturbance, low stress
Large biomass, vegetative growth (similar to K-selected species)
mid-stages of succession
What are characteristics of an S-strategist
Stress tolerators
high stress, low disturbance
biomass production, defense mechanisms, extreme conditions
late stages of succession
What are characteristics of an R-strategist
Ruderals frequent disturbance, low stress short lifespans and reproduce quickly (seed production) similar to r-selected species early stages of succession
Compare and contrast r/K selection theory and C-S-R theory
C similar to K
r similar to R
What is the largest source of introduced weeds in North American cropping systems
Europe (western migration)
Describe three patterns of plant invasion. Which is most difficult to control
Front: controlled movement forward
Streamers: localized extension
Satellite population: sending out seeds to distant locations apart from founding population
What types of plants compete with each other
-
What are some examples of disturbance mentioned in class
-
What is plasticity? What are two types we discussed. Give examples
Phenotypic: change leaf shape
Physiological: change growth rate
What are the characteristics of a habitat that is vulnerable to a plant invasion
Frequent disturbance
Less species richness
Excess resources
Describe the rate of plant population growth during the three phases of plant invasion
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)
