Final Study Guide Flashcards
Invasive species
Non native or alien to the ecosystem or a species whose introduction causes economic, environmental, or human health problems
Define weed
ANy undesirable plant in an environment that is competitive with desirable plants or has no function.
3 ways seeds are dispersed,
Wind, water, animals
Define ecology
The study of organisms in their environment.
What is a perfect flower?
A flower with all reproductive parts.
What does WSSA Stand for?
Weed science society of America.
Dioecious
A plant species that has pistillate and staminate flowers on different plants
Leaf arrangement in which there are two leaves per node.
Opposite
Rhizomes
Horizontal underground stems
A group of organisms within the same species that occur in a given time and space.
Population
Glabrous
Leaf that is smooth
Horizontal above ground stems
Stolons
Dehiscent
Term for type of dry fruit, in which the fruit splits open at maturity
A community plus it’s non living environment
Ecosystem
Leaf arrangement with 3 or more leaves per node
Whorled
A flower with stamens but no pistil
Staminate
Anther and filament make this structure
Stamen
Niche
An organisms place in its environment
Aggregate
A fruit that develops from several ovaries within one flower.
An orderly change in species resulting from modification of the physical environment by the plant community
Succession
Monocots have how many:
Cotyledons in seed?
Number of flower parts?
Leaf venation?
One
3s
Parallel
Dicots have how many:
Cotyledons per seed?
# of flower parts?
Leaf venation?
Two
4s or 5s
Branched
Reasons herbicides are the main method of controlling weeds,
They are cheaper
More reliable
Higher return on investment
Induced dormancy
Type of dormancy in which unfavorable conditions cause sees to go dormant.
r group
Plants that are short lived and produce lots of seed.
The K group
Longer lived less seeds
Obligate weeds
Weeds that have never been found in the wild stage and that grow only in association with man.
A plant that completes its life cycle in one year
Annual
Negative effects of weeds
Reduced yields Increased costs Hard to remove Harbor other crop pests Interfere with harvests Extra cleaning and processing
Ideal characteristics of weeds
Quickly reproducing Competitive Tolerant of stressful conditions Hard to get rid of Produces lots of seeds Quickly germinating
What are the goals of herbicide application?
To kill or suppress the grown of plants
Define formulation
Preparation supplied by manufacturing for use,
Manufacturing process carried out by the formulator in preparing a chemical for packaging,
Dry formulation types
Water soluble powders and water dispensable granules
Liquid formulation types
Water soluble liquids and water dispersal liquids
Dry formulation for direct application
Granules and pellets
What carries can be used for herbicide applicators
Water or other liquids
Adjuvant define
Any substance in herbicide formulation or added to spray tank to modify herbicidal activity
What does a Wetting agent do?
Enables spray deposit to spread and make better contact with plant surface
What are the 5 types of adjuvants
Surfactants Crop oil concentrate Comparability agents Anti foaming agents Drift control agents
What is the range for ground applications?
10 - 20 GPA
What is the range for Air spraying
3- 10 GPA
why do different nozzle sizes matter
Poor control
Crop injury
Wasted chemical
How should herbicides be stored
In a locked temperature controlled area with chemical resistant container treys
How do you dispose of herbicides
Triple rinse, drain, and puncture
What are the 3 types of herbicide names
Common, chemical, trade name
What’s the difference in selective herbicides and non selective
Selective are more toxic to some plants than others
Non selective toxic to all plants
Short residual herbicides
Injure or kill in short periods and used in rotated crops
Long residual herbicides
Soil sterilants, herbicides used in non-crop perennial crops.
Non-residual herbicides
No soil activity noticeable, burn down herbicides and selective post herbicides.
Use to kill crops before planting
Preplant burndown
Herbicide rolled into the soil before planting
Preplant incorporated
Application of herbicide at time of planting or before crop emergence
Preemergence
After crop or weed emergence
Post emergence
Difference between systemic and contact herbicides?
Systemic translocation to phloem
Contact -no movement plant tissue damaged after exposure
Symplastic transport site in plant
Phloem affects photosynthesis
Apoplastic transport location
Xylem moves up only
What types of properties or characteristics are used to group herbicides into families
Physical/ chemical, biological, environmental fate and impact, toxicological hazards.
Measure of the amount of compound that is harmful or lethal when exposed by ingestion, inhalation, or dermal exposure.
Toxicity
Probability of encountering a harmful dose of a compound.
Exposure
What does oncogenicity mean?
Tumor producing
The six Carcinogenicity
Six cancer potential categories
Birth deformities
Tetratogenicity
Genetic abnormality
Mutagenicity
What is the difference between acute and chronic toxicity?
Acute is harm after short exposure and chronic is repeat exposure.
What is mode of action?
The plant process affected by the herbicide.
What is mechanism of action?
The biochemical site within a plant each herbicide directly interacts with.
3 herbicide classification systems
WSSA , AUstrailian, Herbicide resistance action committee
Lipid synthesis inhibitors are in what group?
WSSA 1 and blocks production of phospholipids
Amino acid synthesis inhibitors group?
WSSA 2 reduction of cell division
Nitrogen metabolism inhibitors group?
WSSA 10 increase in ammonia.
Growth regulators group
WSSA 4 clogs xylem and phloem
Mitosis inhibitors group
WSSA 15 microtubules inhibitors
What does LD 50 mean
Dose of a substance lethal to 50% of organisms
What does LC50 stand for?
Concentration of a substance lethal to 50% of organisms
What are the five types of toxicological studies that must be done on herbicides?
Acute, subacute, chronic feeding and oncogenicity, fish and aquatic organisms, birds
How long does it take to develop and register a new herbicide?
10-12 years
Difference between general use pesticide and restricted use?
General use - no reasonable adverse effects on environment and safe to apply
Restricted use- sold only to trained and certified applicators.
Section 18 allows for?
Emergency situation application
IR -4 allows for
Research project anoung state exp stations
DANGER
Highly toxic
Warning
Moderately toxic
caution
Slightly toxic
Preventative measures when spraying?
Long sleeves and pants, gloves, shoes and socks , eyewear.
What is included on a herbicide label?
Mixing instructions, spraying instructions, calibration, application directions.
What informating needed when identifying problems with herbicide?
Locate crop injury, access crop condition, determine if label was followed , record all important information.
What factors other than herbicide application can cause a problem?
Application at wrong stage of growth
What is carrying capacity
The plant density that can be maintained in a given community over time.
What 5 morphological factors of weeds are important?
High germination rate Early extensive root system Large expansive foliage Multiple shoots Climbing growth
What is the LAI? Leaf area index?
Amount of photosynthetic material or leaf suspended per unit of area of land.
When does a weed become competitive in LAI?
At 1.0
How do weeds reach the LAI ?
Through size density,
The interaction among species involving both competition and allelopathy,
Interference
The inhibition of one plant by another through release of toxins,
Allelopathy
The mutually adverse effects of plants which are competing for a resource in short supply.
Competition
Interference of plants of the same species.
Intraspecific interference
Interference of plants of a different species
Interspecific interference
What weed factors are important?
Species cultivar, planting date, planting rate, duration, Growth rate growth habit Allelopathy
What crop factors are important?
Species cultivar Planting date Planting rate Duration Growth rate Allelopathy
Other factors that influence interference?
Weather Soil type Soil fertility Tillage Herbicides and pests
Sigmoid relationship chart axis
Y:
X:
Y: crop yield
X: weed density
What does a longer critical period mean?
The crop is less competitive
How can weeds still have an effect of there is no yield loss from competition?
It can still produce seeds
6 general method of control
Preventative and regulatory Mechanical Cultural Biological Herbicide Biotechnical
What is preventative control?
The prevention of introduction, establishment, and spread of specific weeds.
Farm management practices can be taken to reduce weeds in weed sanitation?
Plant weed free seed, clean equipment, screen irrigation water, inspection, pay special attention
What regulations are in place for weed seed in seeds?
There are noxious laws that prevent noxious weed seed in planting sees or nursery stock.
What are noxious weeds?
Weeds that cannot be sold and are limited by number / lbs
Isolates or prevents the spread of?
Quarantine
Elimination of weed species?
Eradication
Implies a reduction in an infestation level?
Control
What are the mechanical methods of weed control?
Tillage, hand picking, mowing, smothering or mulching.
Advantages and disadvantages of mechanical control
Adv: selective, effective, alternative to herbs, stimulates germination, destroys.
Dis: time consuming, tedious, expensive,
Primary tillage is how deep?
Secondary tillage?
P: 6- 36
Sec: less than 6
Disadvantages of mechanical tillage
Soil erosion, energy requirements, increases weed, damages crops, buries weed seed.
Use of clear plastic film to cover soil for disease and insect control
Solarization
3 areas hand weeding is still used?
Homeowners,
High priced horticulture
Organic farmers
What weed can survive flooding?
Johnsongrass
What types of management practices improve crop competitiveness?
Optimum planting date
Seeding rate
Fertility and irrigation
Cultivar selection
What is biological weed control?
Using natural methods to fight weeds,
Ex. Bugs
Why are biological controls usually aimed at perennial weeds?
2/3s of them are perennial!
Types of biological control? 3
Classical- natural predators
Mycroherbicidal- fungal spores
Feeding- animals
What are the 8 contributions of herbicides?
Cost effective Permit control Reduce tillage Reduce human effort Controls difficult weeds economically Flexible management system Can solve most weed problems
Major risks of using herbicides?
Drift injury
Persistent in soil residues
Inconsistent weed control
Resistant weeds
What is integrated weed management?
The integration of environmentally safe sociologically acceptable control tactics, that reduce weed interference below the economic injury level
What are benefits of integrated weed management?
Wholesome food Increased outputs Economic stability Increased biodiversity Increased productivity
