Presentation on theme: "Turfgrass Herbicide Families & Mode-of-Action"— Presentation transcript:
1Turfgrass Herbicide Families & Mode-of-Action Tim R. MurphyThe University of Georgia
2Herbicide Mode-of Action Mode-of-Action - The entire sequence ofevents that happen from the time the herbicide is absorbed to the eventual plant response (usually death).
3Mode of Action Three phases Absorption Movement to target site Inhibit biochemical reaction
4Herbicide Mode-of-Action The way a herbicide kills or inhibits the growth of susceptible plants!!
5Why understand herbicide MOA? Better understanding of how herbicides perform.Diagnosing herbicide injury.Professionalism.Public relations.
6Herbicide Classification SelectivityHerbicide movement in plantsTiming of applicationChemical FamilyMode of Action
7Herbicide Classification - Selectivity Selectivecontrols or suppresses one species of plant without seriously affecting the growth of another plant species.Example2,4-D will control many broadleaf weeds without seriously affecting turfgrasses.
8Herbicide Classification - Selectivity NonselectiveNonselective herbicides control plants regardless of species.ExamplesRoundup Pro, Finale, Reward, Scythe
9Xylem - nonliving tissue in a plant that transports water and mineral nutrients from the roots to the shoots.Phloem - living tissue that transports sugars from the site of synthesis or storage to the site of use.
10Translocated herbicides move. Contact herbicides do not move in the plantPhloem mobile herbicides move up and down in the plantXylem mobile herbicides move up in the plantTranslocated herbicides move.
11Herbicide Movement in Plants ContactRupture cell membranes.Symptoms appear within hours.Need complete coverage for kill.Xylem MobileTaken up by primarily by roots.Found in older leaves that are exporting sugars.Do not move downward when foliar applied.Phloem MobileMove to points of active growth or food storage.Affect shoot tips, young buds and leaves.Can cause contact burn.
12Mode-of-Action Retention Absorption Translocation to active cell site Inhibit biochemical reactionPlant metabolism or breakdown
15Plant Processes Affected by Turfgrass Herbicides PhotosynthesisAmino acid and protein synthesisCell divisionCell membranesGrowth regulationGrowth inhibitionFatty acid synthesis
16Photosynthesis CO2 + H2O + Sunlight = C6H12O6 OR Carbon dioxide + water + sunlightwill yieldSugar
17Triazines Atrazine – Aatrex, Simazine - Princep Metribuzin – Sencor Used only on warm-season turfgrassesRoot and shoot absorbed (except simazine)Inhibits photosynthesis, eventual membrane disruption, requires lightPre and Post control
18Photosynthetic inhibitors Atrazine, simazine, SencorLight and active photosynthesis needed for activityThese herbicides interrupt energy flow resulting in free radicalsFree radicals react with cell membranesAtrazine on bentgrass
19Ethofumesate Prograss cool-season grasses and overseeded bermudagrass primarily shoot absorbed, some by rootsnot well absorbed after leaf cuticle is formedtranslocated if root or shoot absorbedappears to inhibit photosynthesis and respiration, not well understood
20Bentazon Basagran T/O All warm- and cool-season turfgrasses contact, foliage absorbedlimited translocationcan move in xylem if root absorbedinhibits photosynthetic electron transport
21Photosynthesis Inhibitors SymptomologyInterveinal or veinal yellowing followed by death of plant tissue from leaf margins inwardPOST applications cause rapid browning of plant tissue
23Amino acids Building blocks of plant proteins Enzymes mediate biochemical reactionsStorage roles - seed reservesStructural roles
24Amino Acid Synthesis Inhibitors CharacteristicsMost of these herbicides have soil and foliar activity except glyphosateUndergo significant translocationSoil residual activity herbicide-dependentGenerally, low use-rate herbicides
25Amino Acid Synthesis Inhibitors SymptomologyInjury symptoms on grass include stunting, purple coloration, and inhibited root systems with “bottle-brush” appearanceBroadleaf plant symptomology includes formation of red or purple leaf veins, yellowing of new leaf tissue and blackening of terminal growthGlyphosate injury includes initial yellowing followed by death of affected tissue
26Imidazolinones Image, Plateau warm-season grasses, except bahiagrass rapid shoot and root absorptiontranslocates to meristematic areasinhibits leucine, isoleucine and valine synthesisgrowth is impaired and plants die over 1 to 3 wk period
28SulfonylureasManor, Corsair, SedgeHammer,TranXit, Monument, Revolver, Certaintyrapid shoot and root absorptiontranslocates to meristematic areasinhibits leucine, isoleucine and valine synthesisgrowth is impaired and plants die over 1 to 3 wk period
29SulfonylureasManor, Blade – warm-season grasses, except bahiagrass; also on Ky. BluegrassCorsair – Ky. Bluegrass, bahiagrass, bermudagrassSedgeHammer– all warm- and cool-season turfgrassesRevolver – bermuda, ‘Meyer’ zoysiaMonument – bermuda, zoysiaTranXit – bermuda, zoysia, centipede, overseeded bermudagrassCertainty – bermuda, zoysia, centipede, St. Augustine
30Pyrimidunyloxybenzoic VelocityOverseeded bermudagrassrapid shoot and root absorptionTranslocated via phloeminhibits leucine, isoleucine and valine synthesisgrowth is impaired and plants die over 2 to 3 wk period
31GlyphosateIsopropylamine salt - Roundup Pro , GlyphoMate 41, Razor Pro, ProsecutorAmmonium salt - Roundup ProDryDiammonium salt - TouchDown Profoliage absorbedextensively translocated in phloeminhibits tryptophan, tyrosine and phenylalanine synthesisgrowth is impaired and plants die over 1 to 3 wk period
35Cell DivisionPlant growth is due to cell division and cell elongation.
36Dinitroanilines Benefin - Balan Oryzalin - Surflan Pendimethalin - PendulumProdiamine - BarricadeTrifluralin - TreflanShoot and root absorbed, no translocationInhibit cell division (tubulin formation)Used on most warm- and cool-season turfgrasses
37Dithiopyr Dimension MOA is similar to dinitroanilines Shoot and root absorbed, no translocationInhibit cell division (tubulin formation)Has POST activity on seedling crabgrassUsed on most warm- and cool-season turfgrasses
38DNA Root inhibition Swollen, club shaped roots Surflan on St. Augustinegrasspendimethalin on zoysiagrassDimension on bermudagrassSwollen, club shaped roots
40Asulam Asulox readily absorbed by foliage, minor root absorption translocates in phloem and xyleminhibits cell divisionalso inhibits RNA and protein synthesisused on St. Augustinegrass and ‘Tifway’ bermudagrass
41Pronamide Kerb root absorbed, translocated in xylem controls emerged cool-season grassesinhibits cell divisionUsed only on warm-season turfgrasses
42Cell MembranesContain the cellular contents and regulate the entry and exit of substances that promote or inhibit plant metabolism
43Diquat Reward LS contact, very rapidly absorbed,does not translocate requires light for activitydisrupts electron flow in photosynthesisleads to formation of free radicals which damages cell membranescellular fluids leak, followed by deathused on dormant bermudagrass
44Glufosinate Finale readily absorbed by leaves primarily contact activity, limited translocationinhibits key enzyme involved in conversion of ammonia into amino acidstoxic levels of ammonia build up, causes cell membrane disruption, interferes with photosynthesisused on dormant bermudagrass
45Cell Membrane Disrupters Finale, Reward, ParaquatFinale on zoysiaDamage occurs within hours.Membrane destruction.No redistributionComplete coverage for kill.
46Organic Arsenicals MSMA, DSMA, CMA, CAMA foliage absorbed Mobile in xylem and phloemNot well understood, rapid desiccation indicates cell membrane destructionUsed on cool-season grasses, bermuda and zoysiagrass
47Leaf burn on broadleaves and grasses with yellow leaf tips on grasses Terminal yellowing of grassesMSMA on zoysia
51Oxadiazon Ronstar all turfgrasses, except centipede readily shoot absorbed, less so by rootscan be foliage absorbed, “contact burn”does not significantly translocateLight requiredinhibits key enzyme in chlorophyll synthesis, toxic radicals formed, disrupts cell membranes
52Oxadiazon (Ronstar) PRE 2G – Ky. Bluegrass, Bermuda, seashore paspalum, t. fescue, zoysia, St. Augustine50WSP – bermuda, St. Augustine, zoysiaAnnual grasses, selected broadleaves
53Ronstar 2G and 50WSP - At Sprigging Apply immediately before or after sprigging bermudagrass and zoysiagrassPre-sprigging (1 day before sprigging slightly safer than post-sprigging)Irrigate ASAP for best results
54Carfentrazone QuickSilver Contact, quickly absorbed Fast-acting Inhibits enzyme (protoporphyrinogen oxidase) in chlorophyll synthesis pathway. Leads to formation of toxic intermediates which disrupt cell membranes.
55CarfentrazoneSold with phenoxy herbicides and dicamba as PowerZone and SpeedZoneAll turfgrassesdoes not significantly translocate
56Sulfentrazone Dismiss Root and shoot absorbed Fast-acting Inhibits enzyme (protoporphyrinogen oxidase) in chlorophyll synthesis pathway. Leads to formation of toxic intermediates which disrupt cell membranes.
57Carfentrazone and Sulfentrazone Carfentrazone – POST, all turfgrasssesSulfentrazone – PRE, although does have POST activity
58Growth RegulationNaturally produced hormones (auxins, cytokinins, gibberellins, others) are involved in the regulation of normal growth and development.
59Growth Regulator Herbicides These herbicides affect several plant processes such as cell division, cell enlargement, protein synthesis and respiration. They act by upsetting the normal hormonal balance in plants.
60Growth Regulator Herbicides Phenoxys2,4-D, dichlorpropmecoprop, MCPABenzoicsBanvel, VanquishPicolinic AcidsConfrontTurflonLontrelSpotLightQuinolinecarboxylicDriveTrimec on bermuda
61Phenoxy, Benzoic Acid, Picolinic Acid readily absorbed by foliage, less so by rootsextensively translocatedinterfere with DNA, RNA and protein synthesisresults in uncontrolled cell division and elongationvascular tissues are plugged, 1 to 3 wks
62Quinclorac Drive shoot and root absorbed readily translocates in xylem and phloemMOA not fully understoodBroadleaf's - alters auxin levelsGrasses - affects cell wall synthesis, increases cyanide and ethylene productionUsed on tall fescue, zoysia and bermudagrass, Ky bluegrass
64Phenoxy, Benzoic Acid, Picolinic Acid Phenoxies – used on cool- and warm season turfgrasses, except St. AugustineBenzoic acids - used on cool- and warm season turfgrassesLontrel – all cool- and warm-season grassesConfront – cool- and warm-season grasses, except St. AugustineTurflon – Ky. Bluegrass and tall fescue
65Growth Regulator Herbicides SymptomologyBroadleaf plant stem twisting and curlingLeaves on broadleaf plants exhibit cupping, crinkling, strapping, or drawstring affectSymptoms on grass plants include leaf rolling, crinkling, brace root fusion and malformation.
68Growth Inhibition Exact MOA not known Inhibit root and shoot growth Disrupt cell division, cell enlargementAlso may disrupt lipid synthesis, nucleic acid and protein synthesis
69Growth Inhibitors Bensulide - Betasan, Pre-San Metolachor - Pennant root absorbed, essentially no translocationdisrupts cell division and enlargementMetolachor - Pennantmainly shoot absorbed, some root uptaketranslocates in xyleminhibit root and shoot growthdisrupts protein, fatty acid and lipid synthesis
70Growth Inhibitors Bensulide - Betasan, Pre-San Metolachor – Pennant Cool- and warm-season turfgrassesMetolachor – PennantOnly on warm-season turfgrasses
71Growth Inhibitors Siduron - Tupersan readily absorbed by roots, translocated in xyleminhibits root growth, may disrupt mitosisUsed only on cool-season turfgrasses and zoysiagrass
72Growth Inhibitors Gallery rapidly absorbed by roots, minimal foliage absorptionmoves in xyleminhibits cell wall biosynthesisUsed on all cool- and warm-season turfgrasses
73Fatty Acid SynthesisFatty acids are important components of cell membranesInhibition fatty acid synthesis blocks production of lipids needed for new cell growth.
74Fatty Acid Inhibitors Cyclohexanediones sethoxydim - Vantage, Poastused only on centipedegrass and fine fescueclethodim – Envoyused only on centipedegrassRapidly absorbed by leaves, extensively translocated via phloem to meristemsInhibit key enzyme in fatty acid synthesis
75Fatty Acid Inhibitors Aryl-oxy-phenoxies fenoxaprop - Acclaim Extrafluazifop - Fusilade IIdiclofop - IlloxanRapidly absorbed by leaves, extensively translocated via phloem to meristems, (diclofop translocation is slow)Inhibit key enzyme in fatty acid synthesis
76Fatty Acid Inhibitors Aryl-oxy-phenoxies fenoxaprop - Acclaim Extra used on cool-season grasses and zoysiagrassfluazifop - Fusilade IIUsed only on tall fescue and bermudagrassdiclofop – IlloxanUsed only on bermudagrass
77Fatty Acid Synthesis Inhibitors - Grass Herbicides Reddening of leaf tissue.Discoloration of tissue at and above the nodes.Tissue and leaves in the leaf whorl can easily be separated from the rest of the plant.No broadleaf activity.Fusilade on dallisgrass
78Fatty Acid Synthesis Inhibitors Initial injury in meristematic regions occurs where newest leaves are developingThese regions will turn chlorotic, which is followed by necrosisThe affected area will become “rotted” and will easily separate from rest of plantInjury will develop slowly (7 to 14 days)