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13 Cards in this Set

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Which family is considered the worst weeds?
Graminae
What is the worst weed species in the world?
purple nutsedge
What ways can you classify weeds?
life cycle, habitat, morphology, physiology
What does the EPA consider to be the defining factors in pesticide registration?
site and/or crop
What are 4 strategies that make weeds successful?
1) seed germination over a wide range of conditions
2) rapid growth rate
3) tremendous seed/propagule production
4) self-compatible but able to outcross
When disturbance occurs, what is the order of ecological survival?
r-strategy annuals
k-strategy annuals
k-strategy perennials
k-strategy woody perennials
Life cycle is an important classification method for weeds. Which of the following statements is true regarding the types of weeds in this type of classification?
A. annual weeds reproduce in a single season, while simple perennials persist over several years through specialized vegetative structures
B. biennials complete their life cycle over 2 seasons, while annual weeds persist over several seasons
C. simple perennials reproduce from year to year through overwintering crowns, while creeping perennials use more specialized vegetative structures
D. annual weeds grow vegetatively through the summer and flower/set seed the next spring
C
Discuss the genetic differences between crops and weeds and why this helps weeds stay so successful.
Weeds tend to have a large number of genotypes which allow them to survive in diverse conditions. Also weeds can germinate at different times compared to crops which are bred to have their life cycle at the smae for the convenience of harvesting and other management. Crops are also streamlined with certain attributes unlike weeds that have primary purpose of spreading out so some have vegetative propagules just for this purpose.
List the 4 ways seed is disseminated naturally.
wind, flowing water, animals, forceful dehiscence
List how seeds are disseminated artificially.
1) Planting contaminated seed
2) Livestock manure
3) Equipment
4) Humans
5) Ballasts of ships
6) Introduction
What are the characteristics of k-strategy annuals?
larger seeded species
lower dispersal rate
fewer larger seeds
most crops fit-peanut, corn, soybean
What are the characteristics of k-strategy perennials?
maintain high levels of sexual and vegetative reproduction
More resources into veg propagules than seeds
What are the characteristics of k-strategy woody perennials?
high degree of resources diverted to woody and other persistence structures
slow-growth but not outcompeted
reduced sexual reproduction
climax species