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Turfgrass Management Alanna L. Neely Chapter 7B Turfgrass Pest Management – Weed Control Sustaining a turf of acceptable quality usually means controlling weed species whose presence significantly reduces turf quality. Besides conducting a cultural program that favors vigorous, healthy turfgrass growth, it is sometimes necessary to institute measures for directly controlling potential or actual weed invaders. This frequently involves the selection and application of appropriate herbicides. Weeds: types and species that occur in turf. Herbicides: types and uses for weed control. Weeds Definition: _____________________________________ _____________________________________ ________________- those species that may be a weed under a specific set of circumstances, and a desirable (turfgrass) species under another (i.e., tall fescue, creeping bentgrass, Bermuda grass). ______ _____- those species that are always classed as weeds, regardless of circumstances. Old sayings: ________________________________. Botanical weed types- _____, _____, _____. Annuals _________________________. Winter annuals germinate in the late-summer/ early fall and die the following summer; examples: annual bluegrass, common chickweed, and henbit. Summer annuals germinate in spring and die with the first hard frost in fall; examples: knotweed, spurge, and crabgrass. Biennials ________________________. Perennials _______________________. Simple perennials are propagated by seed; examples: dandelion and plantains. Creeping perennials can reproduce by ________________________________ _____________________. Functional weed types - ________________________________. _____ _____- can be controlled with ________________________________. ______ _____ - generally cannot be controlled with postemergence herbicides (phenoxy, picolinic and benzoic acids) applied to the foliage; however, some annual broadleaf weeds may be controlled with some of the same preemergence herbicides used for crabgrass. Weed Species: Annual Grasses: Yellow foxtail Annual bluegrass Crabgrass Fall Panicum Goosegrass Sandbur Perennial grasses: Bermudagrass Tall Fescue Quackgrass Nimblewill Bentgrass Yellow nutsedge Dallisgrass Broadleaf weeds: Dandelion Broadleaf plantain Buckhorn plantain Common chickweed Mouse-ear chickweed Black medic Purslane Cont.’d Curled dock Red sorrel Chicory Ground ivy Henbit Speedwells cont.’d Yarrow White clover Yellow wood sorrel Knotweed Cont.’d Prostrate spurge Carpetweed Thistles Round-leaved mallow Wild onion/garlic Herbicides Types: A. Preemergence vs. postemergence Preemergence herbicides are applied _____ to the emergence of target weed species; some are effective with early post applications. Postemergence herbicides are applied _____ emergence of the target weed species; application prior to emergence are usually ineffective. Foliar vs. soil applied Foliar- applied herbicides are applied _____ ___________________________________ __________________________________. Soil- applied herbicides are applied _______ ___________________________________ ___________________________________ __________________________________. Contact vs. systemic _____ _____ are not translocated within the plant; they work at the locations of immediate contact with the target weeds. ______ _____- are translocated within the plant to the site (s) of action; excessive rates must be avoided as they might result in less effective, contact action. Selective vs. nonselective ______ _______- selectively kill target species while not adversely affecting nontarget (turfgrass) species, provided they are applied at the proper rate and under the proper conditions. _______ ______- are used either for total vegetation control of for weed species for which no selective herbicides are available. Annual grass control: Preemergence herbicides include DCPA (Dacthal), bensulide (Betasan), Benefin (Balan), oxadiazon (Ronstar), and pendamethalin (pre-M). Postemergence herbicides used to refer to several organic arsenicals (MSMS, DSMA) which had to be applied several times at 7- 10 day intervals; now Acclaim (fenoxyprop- ethly) and Drive (quinclorac) can be used with greater efficacy and safety. Perennial grass control: Roundup (glyphosate) and Finale (glufosinate) are the principal materials used as a spot treatment (directed spray of for total vegetation control. An evolving series of sulfonyl ureas, including Corsair (chlorsulfuron) and Certainty (sulfosulfuron), can be used for selectively controlling selected perennial grasses in some turfgrass communities. A new herbicide, mesotrione, has been successfully for selectivity controlling creeping bentgrass and nimblewill in Kentucky bluegrass turf. Broadleaf weed control: Old standard: 2, 4-D +MCPP + dicamba for broad-spectrum control with bromoxynil for BLW control in seedling turf. Added: 2, 4-D + Dichloroprop for tough BLWs. New add: tryclopyr, or a combination of triclopry and clopyralid, in combination with 2, 4-D for broad-spectrum control. Summary Weeds, including botanical and functional types, and examples of weed species occurring in turf. Herbicides, including types: A. preemergence vs. postemergence B. foliar vs. soil applied C. contact vs. systemic D. selective vs. nonselective Controlling weeds with herbicides: A. annual grasses B. perennial grasses C. broadleaf weeds Closing Statement As in any other facet of turfgrass management, turfgrass weed control often involves the intelligent use of the available tools for accomplishing cultural objectives. In this arena the tools are called herbicides. When used properly, they can provide very satisfactory results; used improperly, they can create more problems than they solve.
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