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Weed management with herbicides

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  1. Crabgrass and other annual grassy weeds

    The first step in managing crabgrass and other annual grassy weeds, including yellow foxtail and goosegrass, is to insure that the cultural practices previously mentioned in this section are being completed on a routine basis. Fundamental cultural practices including mowing, fertilization, irrigation, and aeration when done correctly can significantly decrease annual grassy weed infestations. Cultural practices alone will seldom control crabgrass and other annual grassy weeds completely and there is commonly a need for herbicides to produce results that are commercially acceptable. An effective crabgrass management program utilizes a preemergence herbicide, followed by a postemergence herbicide as needed in the case of less than acceptable preemergence performance or the need to control “escapes”. With the exception of sites in which there are low populations of crabgrass and other annual grasses, postemergence herbicides should not be relied on as the sole control measure. In some situations, preemergence application can be split with 50% of the use rate being applied during the normal application window and the remaining 50% applied 4 to 6 weeks later.
    1. Preemergence materials
      Preemergence herbicides for the control of crabgrass and other annual grasses are applied in early spring. Applications in most areas of Massachusetts should be completed before Forsythia flowers drop or by approximately the first week in May, depending on prevailing weather conditions. Preemergence herbicides are available in sprayable and on-fertilizer formulations. These products need to be watered in to be activated and with the exception of very few materials (e.g. siduron, mesotrione), reseeding of turf cannot be done for three to four months after application. Refer to the product label for specific instructions in regard to safe reseeding intervals. Many annual broadleaf weeds can also be managed with preemergence herbicides.

      Active Ingredient Trade Name(s) Comments
      benefin Balan 2.5G, Team 2G (combination with trifluralin), on-fertilizer formulations  
      bensulide Bensumec 4LF, Pre-San Granular (7G, 12.5G), on-fertilizer formulations  
      corn gluten meal Many formulations available Corn gluten products are 9-10% N by weight and should be factored into fertility program.
      dithiopyr Armortech CGC 40, Crab and Spurge Preventer, Dimension (2EW, EC, Ultra 2SC, Ultra 40WP, Ultra WSP), Dynamo 40WSP, Lifeguard, Quali-Pro Dithiopyr 40WSB, on-fertilizer formulations  
      dimethenamid Tower  
      mesotrione Tenacity Can be used at the time of seeding or overseeding of cool-season turf.
      oxadiazon Ronstar (50WSP, FLO, G) Quali-Pro Oxadiazon 2G, Starfighter (3.17F, 2G), on-fertilizer formulations  
      pendimethalin Pendulum (2G, 3.3EC, AquaCap), Pre-M 3.3EC, on-fertilizer formulations (Halts, Pre-M)  
      prodiamine Barricade (4FL, 65WG), Cavalcade 65WDG, Echelon 45SC (combination with sulfentrazone, Guardrail 65WDG, Knighthawk, Quaili-Pro Prodiamine 65WDG, Stonewall 65WDG, Primeone Prodiamine 65WDG, Proclipse (4F, 65WDG), Resolute 65WDG, on-fertilizer formulations  
      quinclorac Armortech Quin Pro 75DF, Eject 75DF, Drive (75DF, XLR8), PrimeraOne Quinclorac 75DF, Quali-Pro Quinclorac 75DF Can be used before or after seeding or over-seeding of cool-season turfgrasses for the control of crabgrass and other annual grasses.
      siduron Tupersan (50WP, 4.6G), on-fertilizer formulations Can be used at the time of seeding or overseeding of cool-season turf.
    2. Postemergence materials
      Another strategy for managing crabgrass and other annual grasses is the use of postemergence herbicides. The most effective and economical control programs use a preemergence herbicide and a postemergence herbicide, if needed, to clean-up weed escapes.

      Active Ingredient Trade Name(s) Comments
      fenoxaprop-ethyl Acclaim Extra  
      dithiopyr Armortech CGC 40, Crab and Spurge Preventer, Dimension (2EW, EC, Ultra 2SC, Ultra 40WP, Ultra WSP), Dynamo 40WSP, Lifeguard, Quali-Pro Dithiopyr 40WSB, on-fertilizer formulations  
      quinclorac Armortech Quin Pro 75DF, Eject 75DF, Drive (75DF, XLR8), PrimeraOne Quinclorac 75DF, Quali-Pro Quinclorac 75DF, plus several combinations with broadleaf herbicides. Can be used before or after seeding or over-seeding of cool-season turfgrasses for the control of crabgrass and other annual grasses.
      mesotrione Tenacity  
  2. Broadleaf Weeds

    1. Preemergence materials
      Preemergence herbicide application for the control of broadleaf weeds in turf is not a common practice. Most often these weeds are controlled with postemergence broadleaf herbicides discussed in section 2B below. There are, however, some situations in which preemergence herbicides can be incorporated into an effective weed management program. Preemergence herbicides used for the control of crabgrass and other annual grass weeds (section 1A above) will effectively control many annual broadleaf weeds. The herbicides isoxaben and mesotrione are labeled for the preemergence control of many annual and perennial broadleaf weeds. These products need to be applied before weeds germinate.

      Active Ingredient Trade Name(s) Comments
      isoxaben Gallery The only material available exclusively for preemergence control of broadleaf weeds in cool-season turf.
      benefin, bensulide, dithiopyr, mesotrione, oxadiazon, pendimethalin, prodiamine, siduron Several preemergence herbicides used for the control of crabgrass and other annual grass weeds will effectively control many annual broadleaf weeds – see Section IA above.  
    2. Postemergence
      Annual and perennial broadleaf turf weeds can be managed with postemergence herbicides. Sprayable formulations are the most common but granular and on-fertilizer formulations are also available. Broadleaf weeds can be treated at any time of the growing season as long as weeds and cool-season turfgrasses are actively growing. Applications are best done in the fall and spring, avoiding periods when cool-season turfgrasses are heat and/or drought stressed. Winter annual broadleaf weeds that occur in late summer and fall turf seedlings can be controlled with broadleaf herbicides after the turf has received a minimum of three mowings. Postemergence broadleaf herbicides include the phenoxy herbicides (2,4-D, 2,4-DP/dichlorprop, MCPA, MCPP/mecoprop), carfentrazone, clopyralid, dicamba, fluroxapyr, quinclorac, penoxsulam, pyraflufen-ethyl, sulfentrazone and triclopyr. Broadleaf herbicide products are formulated as a single herbicide or in combinations of two, three or four herbicides, as summarized in Table 13:

      Table 13. Active ingredients in commercially-available postemergence herbicide products.
      Click to download Table 13 Adobe PDF icon
  3. Yellow Nutsedge

    Yellow nutsedge is one of the most difficult to control weeds in turf. Applications for yellow nutsedge should be made soon after spring and early summer emergence with application completed before the summer solstice. Heavy infestations can be treated with glyphosate.
    Active Ingredient Trade Name(s) Comments
    bentazon Basagran T&O, Nutgrass Nihilator 2 applications commonly needed. Bentazon is regulated under the Public Drinking Water Supply Protection Regulations in MA, see the Pesticide Regulations section of this guide for details.
    dimethanamid Tower Preemergence material for application where perennial stands of yellow nutsedge are known to exist.
    halosulfuron Manage, SedgeHammer, Halosulfuron Pro Addition of a non-ionic surfactant is required.
    mesotrione Tenacity  
    sulfentrazone Dismiss, Q4 Plus, Surge, Eschelon 4SC (combination with pendimethalin) Sulfentrazone is regulated under the Public Drinking Water Supply Protection Regulations in MA, see the Pesticide Regulations section of this guide for details.
  4. Annual Bluegrass

    Annual bluegrass is a winter annual with perennial biotypes being common in certain turf situations. Annual bluegrass germination occurs primarily in very late summer and fall. Ethofumesate and bispyribac-sodium are labeled for selective postemergence control in certain cool season turfgrass species. Annual bluegrass can be controlled with preemergence crabgrass herbicides when those materials are applied in late summer and fall before germination.
    Active Ingredient Trade Name(s) Comments
    ethofumesate Prograss, Poa Constrictor Applications are best made in the fall and 2 to 3 repeat applications at 3 to 4 week intervals may be needed.
    bispyribac-sodium Velocity SP, Velocity SG Labeled for use only on golf courses and sod fields.
    benefin, bensulide, dithiopyr, mesotrione (suppresses growth), prodiamine, pendimethalin Several preemergence herbicides used for the control of crabgrass and other annual grass weeds will effectively control or suppress annual bluegrass – see Section IA above.  
  5. Non-selective herbicides for turf renovation

    Non-selective herbicides are used to kill existing turfgrass, weeds and other vegetation before turf renovation. Using any of these herbicides for the spot-treatment of existing weeds in established turf is not recommended as turf injury or death will occur in the treated areas. The herbicide glyphosate is strongly translocated and therefore is the best option of the non-selective herbicides for use prior to turf renovation. Glufosinate is not as strongly translocated as glyphosate and therefore can be weak on perennial weeds. Glufosinate can be used when the weed population is comprised of only annual weeds. Pelargonic acid, acetic acid, citric acid, clove oil and d-limonene are contact in nature and will not control perennial weeds making them inappropriate to use in turf renovation.
    Active Ingredient Trade Name(s) Comments
    glufosinate Finale May be weak on perennial weeds.
    glyphosate Roundup Pro Max, GlyphoMate 41, many others  
    pelargonic acid Scythe Not appropriate for turf renovation.
    acetic acid, citric acid, clove oil, d-limonene various materials formulated alone or in combination Not appropriate for turf renovation.
  6. Selective perennial grass control

    Turf areas are often plagued by undesirables: cool-season and warm-season perennial grasses that disrupt uniformity and can result in an unacceptable turf. These grasses include creeping bentgrass, nimblewill, orchardgrass, paspalum, purpletop, quackgrass, tall fescue, timothy and zoysiagrass. A few herbicides are labeled for the selective control of certain grasses, however, most often the area is best treated with glyphosate and reestablished by seeding or sodding.

    Active Ingredient Trade Name(s) Comments
    chlorosulfuron Corsair Controls tall fescue, perennial ryegrass and annual ryegrass.
    glyphosate Roundup Pro Max, GlyphoMate 41, many others Spot or broadcast treatment on all species.
    mesotrione Tenacity Controls creeping bentgrass and nimblewill.
    metsulfuron Manor, MSM Controls perennial ryegrass.