Moa pre final

Agenda

• PRE MOA presentation• Assign topics for future practices• Make wish list for Vince• Seminar -

Blair Miller: Why not ‘Nature Mark’ potato?

Herbicide MOA(Preemergence)

University of Wisconsin-MadisonWeeds Team 2013

According to Facebook

According to Bill Nye the Science Guy

Herbicide MOA(Preemergence)

University of Wisconsin-MadisonWeeds Team 2013

Disclaimer• Wide range of background in this room, stop

me with questions anytime– We will talk about Mode of Action (includes some

herbicide physiology)– Then get into symptomology and selectivity

• ok presentation for teaching MOA(not great), since it is geared for contest– Leaving out elements not important for contest• Very reduced amount of herbicides discussed

Herbicide Mode and Site of Action

• Mode of Action– the metabolic or physiological process impaired or

inhibited by the herbicide• HOW the herbicide controls the plant

• Site of Action– the physical location within the plant where the

herbicide must bind to exert its MOA• WHERE the herbicide acts within the plant

• Mode of Action– the metabolic or physiological process impaired or

inhibited by the herbicide• HOW the herbicide controls the plant

• Site of Action– the physical location within the plant where the

herbicide must bind to exert its MOA• WHERE the herbicide acts within the plant

Herbicide List (PRE) by SoA• PSII, D1protein (Photosystem 2 Inhibitors)– atrazine, metribuzin

• PPO (protoporphyrinogen oxidase inhibitors)– flumioxazin, saflufenacil, sulfentrazone

• HPPD & Diterpene (P-hydroxyphenylpyruvate dioxygenase inhibitor)– isoxaflutole, clomazone

• Microtubule Inhibitors– pendimethalin, trifluralin

• VLCFA (Very long chain fatty acid inhibitors)– s-metolachlor

Other ways to categorize herbicides

• MOA – PSII = photosynthesis inhibitors– HPPD =pigment inhibitors– MI =seedling root inhibitors– PPO = cell membrane disruptors– VLCFA = seedling shoot inhibitors

• Contact vs. Systemic• Xylem vs. Phloem Mobile• Chemical Family

• SELECTIVITY (especially for PREs)

Herbicide List

• list

Photosynthetic Inhibitors (primarily soil-applied)

Triazinesatrazine (AAtrex)

metribuzin (Sencor)

Triazinesatrazine (AAtrex)

metribuzin (Sencor)

Injury Symptoms of Soil-Applied PSI

• Injury symptoms appear after the food reserves in the cotyledons have been exhausted

• The injury symptoms will appear first on the oldest leaves of the plant

• Since these herbicides move in the water conducting tissue (xylem), injury symptomswill follow the path of water movement in the plantRoots Stem Leaves Leaf margins

• Injury symptoms appear after the food reserves in the cotyledons have been exhausted

• The injury symptoms will appear first on the oldest leaves of the plant

• Since these herbicides move in the water conducting tissue (xylem), injury symptomswill follow the path of water movement in the plantRoots Stem Leaves Leaf margins

Injury Symptoms of Soil-Applied PSI

• Injury symptoms appear as a yellowing (chlorosis) of the leaf tissue which, if severeenough, eventually becomes necrotic (dead) tissue

• Initial chlorosis appears at the leaf margins as the herbicide follows the same path as waterthrough the plant

• Advanced chlorosis of the leaf tissue is interveinal (between the veins)– Veins remain green

• Injury symptoms appear as a yellowing (chlorosis) of the leaf tissue which, if severeenough, eventually becomes necrotic (dead) tissue

• Initial chlorosis appears at the leaf margins as the herbicide follows the same path as waterthrough the plant

• Advanced chlorosis of the leaf tissue is interveinal (between the veins)– Veins remain green

Interveinal Chlorosis in cotton

EXTENSIONEXTENSIONUNIVERSITY OF ILLINOISUNIVERSITY OF ILLINOIS

Chlorophyll• Pigments are molecules that absorb

light– Sunlight Pigments PS Food

• Chlorophyll is the plant pigment responsible for the green color of plants

• The synthesis of chlorophyll has many steps, some of which can be inhibited by herbicides

• One family of herbicides that block a step in chlorophyll synthesis is the PPO inhibitors

• Pigments are molecules that absorb light– Sunlight Pigments PS Food

• Chlorophyll is the plant pigment responsible for the green color of plants

• The synthesis of chlorophyll has many steps, some of which can be inhibited by herbicides

• One family of herbicides that block a step in chlorophyll synthesis is the PPO inhibitorshttp://www.youtube.com/watch?v=zaxH4xeMGzM

http://www.youtube.com/watch?v=zaxH4xeMGzM


Protoporphyrinogen Oxidase Inhibitors• These herbicides inhibit a step in the

chlorophyll biosynthesis pathway– protoporphyrinogen oxidase = PPO

inhibitors

• Blockage of this pathway results in the production of free radicals which damage plant membranes– some refer to this family as the “membrane

disruptors”– membrane damage results in characteristic

leaf burn

• When foliar-applied, these herbicides show limited movement in the plant

• These herbicides inhibit a step in the chlorophyll biosynthesis pathway– protoporphyrinogen oxidase = PPO

inhibitors

• Blockage of this pathway results in the production of free radicals which damage plant membranes– some refer to this family as the “membrane

disruptors”– membrane damage results in characteristic

leaf burn

• When foliar-applied, these herbicides show limited movement in the plant


Protoporphyrinogen Oxidase Inhibitors

N-Phenylphthalimides flumioxazin (Valor)

Aryl Triazolinonesulfentrazone (Authority)

Pymidinedionesaflufenacil (Sharpen, Kixor)

N-Phenylphthalimides flumioxazin (Valor)

Aryl Triazolinonesulfentrazone (Authority)

Pymidinedionesaflufenacil (Sharpen, Kixor)


Injury Symptoms of PPO Inhibitors• Soil-applied PPO inhibitors are

mobile within the plant

• Injury often related to multiple factors– variety, soil pH, tillage, environment

• Symptoms often present on cotyledons and hypocotyl, older leaves– reddish lesions – “wrinkled” true leaves

• Soil-applied PPO inhibitors are mobile within the plant

• Injury often related to multiple factors– variety, soil pH, tillage, environment

• Symptoms often present on cotyledons and hypocotyl, older leaves– reddish lesions – “wrinkled” true leaves

Tim says: chlorotic veins in soybeans and corn for soil applied PPO injury


Carotenoid Synthesis Inhibitors (Bleachers)• Carotenoids are “accessory” plant

pigments that protect chlorophyll during photosynthesis– dissipate excess energy from excited

chlorophyll molecules

• Chlorophyll is the pigment responsible for the green color of plants– chlorophyll reflects the green wavelength of

visible light

• Carotenoid synthesis inhibitors block the formation of carotenoids– if carotenoids are absent, chlorophyll can be

destroyed during PS and plants can lose their green color

• Carotenoids are “accessory” plant pigments that protect chlorophyll during photosynthesis– dissipate excess energy from excited

chlorophyll molecules

• Chlorophyll is the pigment responsible for the green color of plants– chlorophyll reflects the green wavelength of

visible light

• Carotenoid synthesis inhibitors block the formation of carotenoids– if carotenoids are absent, chlorophyll can be

destroyed during PS and plants can lose their green color

Bleachers

• Absorbed through roots and shoots, but translocated only in the xylem

• Prevents synthesis of pigments that protect chlorophyl

• Foliage turns white and appears bleached

Ross is not funny


Carotenoid Synthesis Inhibitors

Isoxazalidinonesclomazone (Command)

Isoxazolesisoxaflutole (Balance)

Isoxazalidinonesclomazone (Command)

Isoxazolesisoxaflutole (Balance)


Injury Symptoms of Carotenoid Synthesis Inhibitors• Corn foliage is white

– lack of carotenoids leads to destruction of chlorophyll

• Clomazone carryover – corn generally recovers

• Isoxaflutole injury – corn does not always recover– formulation change from dry to liquid helped

mixing problems– application problems, hybrid sensitivity

issues are not resolved by formulation changes

• Corn foliage is white– lack of carotenoids leads to destruction of

chlorophyll

• Clomazone carryover – corn generally recovers

• Isoxaflutole injury – corn does not always recover– formulation change from dry to liquid helped

mixing problems– application problems, hybrid sensitivity

issues are not resolved by formulation changes

Command Carryover in Oats

Balance Injury, cold wet conditions

Light-activated Herbicides

• How bored is everyone/how am I doing on time

• Reichers explains as multiple SOAs, but kind of one MOA

• PSI, PSII, PPO, HPPD, Glutamine synthetase


Seedling Growth Inhibitors

• These herbicides inhibit the growth and development of weed seedlings, usually beforethe weeds emerge– do not inhibit seed germination

• These herbicides include the dinitroanilines, chloroacetamides, and thiocarbamates

• These herbicides are absorbed by the roots and shoots of weed seedlings– DNAs and Thiocarbamates - root and shoot– Chloroacetamides - shoot

• These herbicides inhibit the growth and development of weed seedlings, usually beforethe weeds emerge– do not inhibit seed germination

• These herbicides include the dinitroanilines, chloroacetamides, and thiocarbamates

• These herbicides are absorbed by the roots and shoots of weed seedlings– DNAs and Thiocarbamates - root and shoot– Chloroacetamides - shoot


Cell Reproduction

• Cell division (mitosis) is the process by which cells reproduce

• During cell division the genetic material (chromosomes) is replicated and distributedevenly to the two new daughter cells

• Specialized structures called microtubules function to distribute the genetic materialequally to the two new cells

• Cell division (mitosis) is the process by which cells reproduce

• During cell division the genetic material (chromosomes) is replicated and distributedevenly to the two new daughter cells

• Specialized structures called microtubules function to distribute the genetic materialequally to the two new cells


Dinitroaniline Herbicides

SoA: Microtubule Inhibition

trifluralin (Treflan, others)pendimethalin (Prowl)

SoA: Microtubule Inhibition

trifluralin (Treflan, others)pendimethalin (Prowl)


Injury Symptoms of DNA Herbicides• Corn seedlings are usually stunted with

club-shaped roots and limited secondary root development– characteristic symptom of DNA, also corn

nematodes

• Foliage often with purple leaf margins, probably attributable to poor phosphorus uptake– limited root growth leads to limited nutrient

absorption

• Lateral roots of soybeans may be pruned from excessive rates of DNA herbicides. Hypocotyls may swell (callus) and crack, causing lodging late in the season

• Corn seedlings are usually stunted with club-shaped roots and limited secondary root development– characteristic symptom of DNA, also corn

nematodes

• Foliage often with purple leaf margins, probably attributable to poor phosphorus uptake– limited root growth leads to limited nutrient

absorption

• Lateral roots of soybeans may be pruned from excessive rates of DNA herbicides. Hypocotyls may swell (callus) and crack, causing lodging late in the season


Chloroacetamide Herbicides• These herbicides inhibit primarily shoot

development in susceptible species– root symptoms not common

• Primary mechanism of plant death not completely understood– some speculate these herbicides interfere

with cell division by inhibiting formation of very long chain fatty acids

• Many formulated with safeners to reduce corn injury potential

• These herbicides inhibit primarily shoot development in susceptible species– root symptoms not common

• Primary mechanism of plant death not completely understood– some speculate these herbicides interfere

with cell division by inhibiting formation of very long chain fatty acids

• Many formulated with safeners to reduce corn injury potential


Chloroacetamides and Thiocarbamates

ChloroacetamidesS-metolachlor (Dual II Magnum) acetochlor (Harness,TopNotch, etc)

ChloroacetamidesS-metolachlor (Dual II Magnum) acetochlor (Harness,TopNotch, etc)


Injury Symptoms of Chloroacetamides• Injury symptoms are most frequent

under cool, wet conditions– those conditions that slow corn growth

• Corn seedlings may leaf-out underground. Following emergence, leaves may fail to unfurl correctly, and the leaves may appear crinkled– have observed leaf rolling on much taller

corn, but is this more herbicide or environment related?

• Symptoms typically dissipate when temperatures increase and soils dry

• Injury symptoms are most frequent under cool, wet conditions– those conditions that slow corn growth

• Corn seedlings may leaf-out underground. Following emergence, leaves may fail to unfurl correctly, and the leaves may appear crinkled– have observed leaf rolling on much taller

corn, but is this more herbicide or environment related?

• Symptoms typically dissipate when temperatures increase and soils dry


Injury Symptoms of Chloroacetamides

• Soybean leaves may also appear crinkled or puckered. A shortened leaf mid-vein gives theleaf a heart-shaped or "draw string" appearance – I think it is hard to differentiate b/n PRE PPO

symptomology on soybeans

• Soybean leaves may also appear crinkled or puckered. A shortened leaf mid-vein gives theleaf a heart-shaped or "draw string" appearance – I think it is hard to differentiate b/n PRE PPO

symptomology on soybeans

Buggy Whipping

“Stumble up to a plot”

• We talked a lot about how herbicides work and their symptomology

• Next step is to put together keys for selectivity of crops and weeds

• Looking at plots this summer will help immensely!

• Until then “roll over into a plot”

Quiz next week!!!

Moa pre final

Technology

Transcript of Moa pre final