Final Review Flashcards
What is a weed?
A weed is a plant that interferes with the growth of desirable plants, is persistent and negatively affects human activity .
Why is weed science a broad discipline?
Weeds create problems in many or most environments. It’s the study of the interference of these plants in human activity. It’s not just agronomic crops anymore, it’s in managed and natural ecosystems.
Negative impacts of weeds
- Decrease quality/quantity of crops
- increase production costs
- human health and allergies
- decrease land value
- reduce water quality
- recreation value
- livestock poisoning
- decrease biodiversity
name a significant wetland weed
Purple loosestrife
significant terrestrial weed
horseweed
name one significant parasitic weed
dodder
what are several growth traits that are common to weeds?
- propagules can germinate in many enviroments
- discontinuous germination
- rapid growth
- ability to compete interspecifically
- well adapted to disturbance
- co adapted with crops
- -herbicide resistance
- -growth habits (prostrate)
- -crop mimics
several beneficial traits of weeds?
- erosion control
- medicinal purposes
- insect and disease traps
- pollution control
- food
How are weeds classified?
life cycle
habitat
morphology
botanically
->must consider the biology of the weed, its neighbors, the constraints of the environment, and budget
what are several reproductive traits that are common to weeds?
seed produced as long as conditions permit
seed dormancy
self-pollinating
short and long distance dispersal mechanisms
cross-pollination by unspecialized pollinators or wind
Why is weed management so complex?
synonymous with vegetation management
a manipulation of plants against the natural evolutionary pressures, and to promote the growth of a desired species
what are the requirements of a Weed Management Plan?
- **Ghiboiie! **
- Goals
- History
- ID
- Biology
- Options
- Integration
- Implementation
- Evaluation
prevention versus control versus eradication
prevention is the most effective, economical and ecologically sound approach to controlling weeds. Control is working to manage populations thart are already established. Eradication is very hard and requires getting rid of all parts of a plant and its propagules.
What is EDRR?
Early Detection and Rapid Response
controlling populations while the populations are localized and small
costs are typically less
more likely to eradicate weed infestations and prevent them from growing to unmanageable sizes.
What are some specific prevention techniques?
- Planting certified seed
- keeping equipment clean and screen water
- spot treat small infestations
- use mulches and other barriers
- make inspections regularly
What are some laws to prevent the spread of weeds?
- Federal noxious weed act (1975)
- Plant Protection Act (200)
- State Noxious Weed Laws
- Oregon Noxious Weed Law
- A (not yet here)
- B (Problem, biocontrol)
- T (targeted, priority)
- Oregon Seed Law
- Prohibited versus restricted
How is weed control defined?
the suppression of a weed to the point where its impact is minimized
What are the four major breeding systems of weeds?
Outcrossing, Self-pollination, clonal, mixed mating
Define Outcrossing
gametes that form zygote are genetically dissimilar
- leads to more diversity within a population
- less diversity among populations
Define self-pollination
gametes that form the zygote are genetically very similar
genetic diversity within a population is low
diversity among populations is high
define vegetative propagation
offspring are genetically identical
genetic diversty is hard to predict
define mixed mating systems
most common method in weeds
common combos:
-falcutative selfing in an outcrossing species
predominately selfing with low level of outcrossing
outcrossing with clonal capacity
facultative apomoxis
define apomixis
asexual form of reproduction where a seed is formed without fertilization
-dandelion, blackberry, kentucky bluegrass
Advantages of seed reproduction:
+ = genetic diversty
seeds are a complete package - preserved in time and against harsh environments, easily dispersed, many are produced

