Unit 2 Exam

Biological selectivity of weeds

Biological selectivity of weeds

herbicide kills weed with minimal effect to crop because of natural tolerance or through GMOs

What amount of older herbicides were needed

lbs per acre

what amount of herbicide is needed now

ounces per acre

pre-emergence herbicide

before weeds emerge

pre-plant herbicide

before crop is planted

broad cast application

treat entire area

ground applicators

type of broadcast application using tractors

aerial application

broadcast application using crop dusters

herbigation

type of broadcast application using irrigation to distribute herbicide

Banding

application of herbicide on a specific region of the feild

what scenarios is banding used?

used in orchards, vinyards, and nurseries

Directed spray

spray that specifically targets weeds without touching crops

hooded boom

protects crop during directed spray

Spot spray

used primarily for post emergence application for targeting weeds in patches.

can have a 90% savings

advantage to spot spray

Rope wick applicator

touches weeds taller than crop and applies systemic herbicide to weed

Active Ingredient

herbicide doing the work

inactive ingredient

compounds that make the herbicide work better

Additives

designed to help herbicide not react in water and minimize off-target damage

disadvantages to tillage

can’t work in wet soil, and causes land to be more susceptible to dust storms

IWM Integrated weed managment

practices multiple techniques to keep weeds off balance and avoid resistance

elements to IWM

physical, cultural, biological, and chemical

Invasive definition

non-indignous species that becomes established in a natural plant community and replaces native vegetation and is likely to cause economic harm or environmental harm

noxious weed definition

native plant that is injurious to agricultural or horticultural crops and/or humans and livestock

how many noxious weeds in MO?

10 genera 12 species

what percent of species in MO are considered non-native

25%

most abundant invasive weed in US

downy brome. introduced in wheat from europe

are all non-native species a problem?

no, soybeans are fine

reasons plants may become invasive

1. comes to new area without predators

2. ability to grow rapidly

3. we do not recognize them as invasive since they are grown as ornamentals

4. prolific reproduction so native species out competed

5. ability to thrive in a wide variety of habitats

6. exhibit defense mechanisms that put other plants at a disadvantage

7. abiltiy to exploit limiting factors

8. invasive species are not recognized by native animals

serecea lespedeza history

brought over as erosion control but it got out of hand

novel weapon hypothesis

invasives produce chemicals that native plants are not used to

enemy release only the healthiest plants

people introduce non-sick plants thus don’t have any of the natural predators

Better competitors hypothesis

must be able to last longer in competition

Smeda theory

start at low levels and by the time people recognize them they are beyond our ability to handle them

where are invasive weeds the biggest problem in the USA

western states and right of ways

FIFRA (Federal insecticide Fungicide rodenticide act)

developed in 1947 from USDA and said that pesticides for shipment must be registered with the secretary of agriculture

What happened before FIFRA

no container guidelines

No restrictions on transport

no warrenty of product

no saftey or effectivess warnings

EPA (Environmental protection agency)

the fire of the OH river catelized the creation of this organization

Goal of pesticide labels

dictate how pesticide is to be used, number of applications, crop to be used on, pre-harvest, rentry intervals and disposal

Who is responsible for pesticide use and how long?

you the user forever

ways to reduce invasive weeds

-eliminate propigation factors

-use effective tools

-establish native species in the open spaces

-education of the public

-understand the weed

-organization of mutliple groups of people

meaning of label for manufacturer

it’s their permit to sell, and how they pay for research and development

meaning of label for buyer or user

how to use the product correctly

meaning of label to federal or state government

method of control, distribution, sale, use, and disposal

label meaning to physicians

source of informationg for treating patients

PIP

Plants incorperates Protectants

Trade name

name of pesticide copyrighted by the company (subject to change)

common name

simplified version of chemical name, can have same common name for different trade names

chemical name

IUPAC name that gives provides the proper chemical nomenclature

General use pesticides

will not cause adverse affects if used as directed

resitricted use pesticides

must possess proper license for each state you use it in

reciprocity

able to transfer restricted use license to ajoining states

Caution signal word

slightly toxic if consumed or inhaled or absorbed

warning signal word

moderately toxic if consumed inhaled or absorbed

danger signal word

very poisonous or irritating to skin or eyes, use with extreme care

who needs a license?

certified commercial applicators

certified non-commercial apllicators

certified public applicators

1A license

agricicultural plant pest control

3 license

ornamental and turf pest control

6 license

right of way pest control

why regulate pesticides

protect the public from adverse effects

ensure proper use of chemicals to reap the full benefits

legistlation ensures consistant use of chemicals

demonstrates to the public that it is safe to use

Food and drug act of 1906

first law specifically addressing pesticides, arsinec in the UK

Insecticide act of 1910

targeted unethecal selling of mislabed pesticides, did not address the toxic affects just made you label them

Federal Food Drug and Cosmetic Act (FFDCA) 1938

set standards for labeling products in response to food poisoning cases

FIFRA act of 1947

addressed the safety of pesticides and the environment. Started looking at residues in the environment and showed that the company was responsible for making safe pesticides

FIFRA ammendment (delaney clause)

stated that no substances known to cause cancer in humans or animals would be deliberately put in food.

problem with delaney clause

did not account for parts per trillion that are now able to be found in food since our technology is so much better.

Food Quality Protection Act (1996)

abolished delaney clause, set a new standard for reasonable amount regarding pesticides, created adult and child standards

Risk assessment cup

introduced with the Food quality protection act, has a risk cup for each pesticide that takes into account the exposure from all different avenues and will not allow the cup to get above a certain level

how are most pesticides discovered

serendipitously

computer assisted modeling (analogs)

Steps for getting a compound released

analog studies

mice studies

primary studies

secondary studies

field trials

EPA requriments for pesticide to be released

pesticide composistion is valid

EPA label good

no adverse affects on non-target organisms and the environment

best canditate for how to handle resistant plants?

non-selective, systemic herbicides and have your crop be resistant

PIP

plant incorperated protectants. plants are build with anti herbivory and weed suppressing chemicals

Early Use Permit (EUP)

can be issued by EPA if it is an emergency and you are going to use it on lesss than ten acres of land or less than one acre of aquatic, effective for 1 year

section 18 of FIFRA

allows the unregistered use of an herbicide for a limited use for a special cost. one year permit, must be an emergency and requires EPA support

Section 24c of FIFRA

special local need. a state can register the early used but it must have a special need. this can be longer than a year but EPA still must approve

4 phases of soil

liquid, solid, gaseous, living. all impact herbicide activity

concentration gradient rule for herbicide

must have high concentration outside plant so it will go to the inside

what happnes to the herbicide if the parent molecule changes

it is no longer the herbicide you started with

Adsorption

herbicide ions stick to the surface of soil particles

clay

the most potential adsorption locations as well as the most surface area since they are so small

size order of soil particles large to small

sand→silt→clay

Kd

soil sorption coefficient

what does kd measure

ratio of herbicide bound to the soil vs free in soil solution

does water solubility affect Kd?

nope, not really

a high Kd value means

more herbicide adsorbed to the soil than free in solution

Absorption

referes to the passage of an herbicide through the surface of a particle

Absorbed herbicides are

unavailable until the particle they are in breaks down

what soils need more herbicide in order to work?

soils high in clay or organic material since more absorption and adsoprtion means less herbicide in soil solution for plant to use

Desorption

the release of absorbed or adsorbed herbicides into soil solution

what is the most important process to initiate desorption?

RAIN it takes away the binding sites on the soil particles from the herbicide and forces the herbicide inot the solution

CEC (cation exchange capasity)

the higher the CEC the greater the ability to store plant nutrients in the soil

Soil CEC increases with

clay and organic matter. generally adsorption of herbicides increases as CEC increases

Acidic pH affect on adsorption

higher adsorption

photodegredation

UVB and UVA create changes in the parent molecules thorugh radiation from the sun

Microbes and herbicide effect

microbes will break down molecules or take pieces off of the parent molecule changing the shape/function

leaching

movement of herbicide with water

Koc

determines how subject an herbicide is to leaching

to find Koc

divide Kd by the wieght fraction of the organic carbon in the soil

high Koc value

correlates to less mobile herbicide (higher kd)